NAPAC2022 - List of Keywords (electron)

Paper	Title	Other Keywords	Page
MOODE1	Applications of Particle Accelerators	linac, site, neutron, target	1
	M. Uesaka JAEC, Tokyo, Japan
	Applications of particle accelerators amid global policies of carbon neutrality and economic security. are reviewed. Downsizing of high energy large scaled accelerators by advanced technologies enables a variety of medical and industrial uses. One of the highlights is upgrade of sustainable supply chain of medical radioisotopes by the best mix of research reactors and accelerators. 99Mo/99mTc for diagnosis are going to be produced by low enriched U reactor and proton-cyclotron, electron rhodotron and electron linac. Moreover, the theranostics by 177Lu (beta) and 211At/225Ac (alpha) are going to be realized. Proton-cyclotron and electron linac are expected to produce them soon. This new affordable radiation therapy should play an important role in the IAEA project of Rays of Hopes. Next, proof-of-principle trails of on-site bridge inspection of the portable X-band (9.3 GHz) electron linac X-ray/neutron sources are under way. The technical guideline for the practical inspection is to be formed in a couple of years. Ultimate micro-accelerator for microbeam applications is dielectric laser accelerator, such as ACHIP project. Updated projects and results are also introduced.
	Slides MOODE1 [3.065 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOODE1
About •	Received ※ 02 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 11 August 2022
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MOYD4	Model Parameters Determination in EIC Strong-Strong Simulation	simulation, proton, collider, emittance	9
	D. Xu, C. Montag BNL, Upton, New York, USA Y. Hao FRIB, East Lansing, Michigan, USA Y. Luo Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA J. Qiang LBNL, Berkeley, California, USA
	The ion beam is sensitive to numerical noise in the strong-strong simulation of the Electron-Ion Collider (EIC). This paper discusses the impact of model parameters — macro particles, transverse grids and longitudinal slices — on beam size evolution in PIC based strong-strong simulation. It will help us to understand the emittance growth in strong-strong simulation.
	Slides MOYD4 [0.849 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYD4
About •	Received ※ 02 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 11 August 2022
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MOYD5	Tolerances of Crab Dispersion at the Interaction Point in the Hadron Storage Ring of the Electron-Ion Collider	proton, simulation, dynamic-aperture, cavity	12
	Y. Luo, J.S. Berg, M. Blaskiewicz, C. Montag, V. Ptitsyn, F.J. Willeke, D. Xu BNL, Upton, New York, USA Y. Hao FRIB, East Lansing, Michigan, USA V.S. Morozov ORNL RAD, Oak Ridge, Tennessee, USA J. Qiang LBNL, Berkeley, California, USA T. Satogata JLab, Newport News, Virginia, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. The Electron Ion Collider (EIC) presently under construction at Brookhaven National Laboratory will collide polarized high energy electron beams with hadron beams with luminosity up to 10³⁴ cm^-2 s^-1 in the center mass energy range of 20 to 140 GeV. Due to the detector solenoid in the interaction region, the design horizontal crabbing angle will be coupled to the vertical plane if uncompensated. In this article, we estimate the tolerance of crab dispersion at the interaction point in the EIC Hadron Storage Ring (HSR). Both strong-strong and weak-strong simulations are used. We found that there is a tight tolerance of vertical crabbing angle at the interaction point in the HSR.
	Slides MOYD5 [1.183 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYD5
About •	Received ※ 01 August 2022 — Accepted ※ 04 August 2022 — Issue date ※ 15 August 2022
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MOYE6	Spin-Polarized Electron Photoemission and Detection Studies	experiment, simulation, cathode, polarization	26
	A.C. Rodriguez Alicea, R. Palai University of Puerto Rico, Rio Piedras Campus, San Juan, Puerto Rico O. Chubenko, S.S. Karkare Arizona State University, Tempe, USA L. Cultrera BNL, Upton, New York, USA
	Funding: Brookhaven National Laboratory and the Department of Energy of United States under contract No. DE-SC0012704 Also, the Center for Bright Beams, NSF award PHY-1549132. The experimental investigation of new photocathode ma- terials is time-consuming, expensive, and difficult to accom- plish. Computational modelling offers fast and inexpensive ways to explore new materials, and operating conditions, that could potentially enhance the efficiency of polarized electron beam photocathodes. We report on Monte-Carlo simulation of electron spin polarization (ESP) and quantum efficiency (QE) of bulk GaAs at 2, 77, and 300 K using the data obtained from Density Functional Theory (DFT) cal- culations at the corresponding temperatures. The simulated results of ESP and QE were compared with reported exper- imental measurements, and showed good agreement at 77 and 300 K.
	Slides MOYE6 [6.235 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYE6
About •	Received ※ 03 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 04 September 2022
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MOZD2	Preliminary Study of a High Gain THz FEL in a Recirculating Cavity	radiation, undulator, FEL, GUI	30
	A.C. Fisher, P. Musumeci UCLA, Los Angeles, California, USA
	The THz gap is a region of the electromagnetic spectrum where high average and peak power radiation sources are scarce while at the same time scientific and industrial applications are growing in demand. Free-electron laser coupling in a magnetic undulator is one of the best options for radiation generation in this frequency range, but slippage effects require the use of relatively long and low current electron bunches to drive the THz FEL, limiting amplification gain and output peak power. Here we use a circular waveguide in a 0.96 m strongly tapered helical undulator to match the radiation and e-beam velocities, allowing resonant energy extraction from an ultrashort 200 pC 5.5 MeV electron beam over an extended distance. E-beam energy measurements, supported by energy and spectral measurement of the THz FEL radiation, indicate an average energy efficiency of ~ 10%, with some particles losing > 20% of their initial kinetic energy.
	Slides MOZD2 [7.005 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZD2
About •	Received ※ 04 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 13 August 2022
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MOZD4	Uncertainty Quantification of Beam Parameters in a Linear Induction Accelerator Inferred from Bayesian Analysis of Solenoid Scans	solenoid, experiment, induction, space-charge	34
	M.A. Jaworski, D.C. Moir, S. Szustkowski LANL, Los Alamos, New Mexico, USA
	Linear induction accelerators (LIAs) such as the DARHT at Los Alamos National Laboratory make use of the beam envelope equation to simulate the beam and design experiments. Accepted practice is to infer beam parameters using the solenoid scan technique with optical transition radiation (OTR) beam profiles. These scans are then analyzed with an envelope equation solver to find a solution consistent with the data and machine parameters (beam energy, current, magnetic field, and geometry). The most common code for this purpose with flash-radiography LIAs is xtr [1]. The code assumes the machine parameters are perfectly known and that beam profiles will follow a normal distribution about the best fit and solves by minimizing a chi-square-like metric. We construct a Bayesian model of the beam parameters allowing maching parameters, such as solenoid position, to vary within reasonable uncertainty bounds. Posterior distribution functions are constructed using Markov-Chain Monte Carlo (MCMC) methods to evaluate the accuracy of the xtr solution uncertainties and the impact of finite precision in measurements. [1] P.W. Allison, "Beam dynamics equations for xtr," Los Alamos Technical Report LA-UR-01-6585. November 2001.
	Slides MOZD4 [1.082 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZD4
About •	Received ※ 05 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 20 August 2022
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MOZD5	ERL-Based Compact X-Ray FEL	FEL, emittance, optics, laser	37
	F. Lin, V.S. Morozov ORNL RAD, Oak Ridge, Tennessee, USA J. Guo, Y. Zhang JLab, Newport News, Virginia, USA
	Funding: Work supported by UT-Battelle, LLC, under contract DE-AC05-00OR22725, and by Jefferson Science Associates, LLC, under contract DE-AC05-06OR23177 We propose to develop an energy-recovery-linac (ERL)-based X-ray free-electron laser (XFEL). Taking advantage of the demonstrated high-efficiency energy recovery of the beam power in the ERL, the proposed concept offers the following benefits: i) recirculating the electron beam through high-gradient superconducting RF (SRF) cavities shortens the linac, ii) energy recovery in the SRF linac saves the klystron power and reduces the beam dump power, iii) the high average beam power produces a high average photon brightness. In addition, such a concept has the capability of delivering optimized high-brightness CW X-ray FEL performance at different energies with simultaneous multipole sources. In this paper, we will present the preliminary results on the study of feasibility, optics design and parameter optimization of such a device.
	Slides MOZD5 [2.870 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZD5
About •	Received ※ 02 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 04 August 2022 — Issue date ※ 11 September 2022
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MOZD6	Accelerator Physics Lessons from CBETA, the First Multi-Turn SRF ERL	linac, SRF, cavity, photon	41
	K.E. Deitrick JLab, Newport News, Virginia, USA G.H. Hoffstaetter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	The Cornell-BNL ERL Test Accelerator (CBETA) has been designed, constructed, and commissioned in a collaboration between Cornell and BNL. It focuses on energy-saving measures in accelerators, including permanent magnets, energy recovery, and superconductors; it has thus been referred to as a green accelerator. CBETA has become the world’s first Energy Recovery Linac (ERL) that accelerates through multiple turns and then recovers the energy in SRF cavities though multiple decelerating turns. The energy is then available to accelerate more beam. It has also become the first accelerator that operates 7 beams in the same large-energy aperture Fixed Field Alternating-gradient (FFA) lattice. The FFA is constructed of permanent combined function magnets and transports energies of 42, 78, 114, and 150 MeV simultaneously. Accelerator physics lessons from the commissioning period will be described and applications of such an accelerator from hadron cooling to EUV lithography and from nuclear physics to a compact Compton source will be discussed.
	Slides MOZD6 [3.207 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZD6
About •	Received ※ 23 July 2022 — Revised ※ 27 July 2022 — Accepted ※ 03 August 2022 — Issue date ※ 06 August 2022
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MOZE4	Ceramic Enhanced Accelerator Structure Low Power Test and Designs of High Power and Beam Tests	cavity, impedance, accelerating-gradient, simulation	49
	H. Xu, M.R. Bradley, L.D. Duffy, M.A. Holloway, J. Upadhyay LANL, Los Alamos, New Mexico, USA
	Funding: Research was supported by the Laboratory Directed Research and Development program of Los Alamos National Laboratory, under project number 20210083ER. A ceramic enhanced accelerator structure (CEAS) uses a concentric ceramic ring placed inside a metallic pillbox cavity to significantly increase the shunt impedance of the cavity. Single cell standing wave CEAS cavities are designed, built, and tested at low power at 5.1 GHz. The results indicate 40% increase in shunt impedance compared to that of a purely metallic pillbox cavity. A beam test setup has been designed to use a single cell CEAS cavity to modulate a 30-keV direct-current (DC) electron beam at an accelerating gradient of 1 to 2 MV/m to verify the beam acceleration capability of the CEAS concept and to study the potential charging effect on the ceramic component during the operation. Another single cell standing wave CEAS cavity has been designed for high power test at 5.7 GHz for the high accelerating gradient capability.
	Slides MOZE4 [1.652 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZE4
About •	Received ※ 01 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 07 October 2022
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MOPA13	Design of a Surrogate Model for MUED at BNL Using VSim, Elegant and HPC	simulation, gun, detector, laser	72
	S.I. Sosa Guitron, S. Biedron, T.B. Bolin UNM-ECE, Albuquerque, USA S. Biedron Element Aero, Chicago, USA S. Biedron UNM-ME, Albuquerque, New Mexico, USA
	Funding: U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Program of Electron and Scanning Probe Microscopes, award number DE-SC0021365. The MeV Ultrafast Electron Diffraction (MUED) instrument at Brookhaven National Laboratory is a unique capability for material science. As part of a plan to make MUED a high-throughput user facility, we are exploring instrumentation developments based on Machine Learning (ML). We are developing a surrogate model of MUED that can be used to support control tasks. The surrogate model will be based on beam simulations that are benchmarked to experimental observations. We use VSim to model the beam dynamics of the radio-frequency gun and Elegant to transport the beam through the rest of the beam-line. We also use High Performance Computing resources from Argonne Leadership Computing Facility to generate the data for the surrogate model based on the original simulation as well as training the ML model.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA13
About •	Received ※ 01 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 21 August 2022
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MOPA17	Symplectic Particle Tracking in a Thick Nonlinear McMillan Lens for the Fermilab Integrable Optics Test Accelerator (IOTA)	solenoid, optics, simulation, lattice	83
	B.L. Cathey, G. Stancari, T. Zolkin Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The McMillan system is a novel method to increase the tune spread of a beam without decreasing its dynamic aperture due to the system’s integrability. While the ideal system is based on an infinitely thin kick, the physical design requires a thick electron lens, including a solenoid. Particle transport through the lens is difficult to simulate due to the nature of the force on the circulating beam. This paper demonstrates accurate simulation of a thick McMillan lens in a solenoid using symplectic integrators derived from Yoshida’s method.
	Poster MOPA17 [2.290 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA17
About •	Received ※ 03 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 09 October 2022
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MOPA30	LCLS-II BCS Average Current Monitor	cavity, hardware, MMI, LLRF	120
	N.M. Ludlow, T.L. Allison, J.P. Sikora, J.J. Welch SLAC, Menlo Park, California, USA
	LCLS-II is a 4th generation light source at the SLAC National Accelerator Laboratory. LCLS-II will accelerate a 30 µA electron beam with a 1 MHz bunch rate with a new superconducting Continuous Waveform (CW) RF accelerator. The Average Current Monitor (ACM) is part of the Beam Containment System (BCS) for the LCLS-II accelerator. The Beam Containment System is a safety system that provides paths to safely shut the accelerator beam off under a variety of conditions. The Average Current Monitor is a beam diagnostic within the BCS that is used to verify that the accelerator is producing the appropriate current level and to limit beam power to allowed values to protect the machine and beam dumps. The average beam current is obtained by measuring the power level induced by the beam in a low Q cavity. By knowing the Q, the beta, and the coupling of the cavity, the instantaneous charge can be calculated, then integrating the instantaneous charge over one millisecond will yield the average current. This paper will discuss progress in the checkout process of the ACM LLRF hardware leading to LCLS-II commissioning.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA30
About •	Received ※ 16 July 2022 — Revised ※ 05 August 2022 — Accepted ※ 24 August 2022 — Issue date ※ 06 October 2022
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MOPA34	Noise in Intense Electron Bunches	laser, radiation, FEL, experiment	128
	S. Nagaitsev, D.R. Broemmelsiek, J.D. Jarvis, A.H. Lumpkin, J. Ruan, G.W. Saewert, R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA Z. Huang, G. Stupakov SLAC, Menlo Park, California, USA Y.K. Kim University of Chicago, Chicago, Illinois, USA
	We report on our investigations into density fluctuations in electron bunches. Noise and density fluctuations in relativistic electron bunches, accelerated in a linac, are of critical importance to various Coherent Electron Cooling (CEC) concepts as well as to free-electron lasers (FELs). For CEC, the beam noise results in additional diffusion that counteracts cooling. In SASE FELs, a microwave instability starts from the initial noise in the beam and eventually leads to the beam microbunching yielding coherent radiation, and the initial noise in the FEL bandwidth plays a useful role. In seeded FELs, in contrast, such noise interferes with the seed signal, so that reducing noise at the initial seed wavelength would lower the seed laser power requirement. Status of the project will be presented.
	Poster MOPA34 [0.638 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA34
About •	Received ※ 10 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 14 August 2022 — Issue date ※ 24 August 2022
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MOPA45	Vacuum Electron Devices in the 88-Inch Cyclotron	cyclotron, ECR, radiation, plasma	154
	M. Kireeff Covo, J.Y. Benitez, P. Bloemhard, J.P. Garcia, B. Ninemire, L. Phair, D.S. Todd, D.Z. Xie LBNL, Berkeley, California, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract No. DE-AC02-05CH11231 The 88-Inch Cyclotron at Lawrence Berkeley National Laboratory is a sector-focused cyclotron that has light- and heavy-ion capabilities and supports a local research program in Nuclear Science and is the home of the Berkeley Accelerator Space Effects Facility, which studies effects of radiation on microelectronics, optics, materials, and cells. The cyclotron utilizes several vacuum electron devices (VEDs) in different systems, mainly to convey plasma heating, high power RF generation, and high-voltage and current DC power generation. VEDs have been proven reliable, robust, and radiation resistant. They also have wide range, good response against transients, and stable operation with load mismatch during system tuning, instabilities, or breakdowns. The paper will describe applications of these devices in the 88-Inch Cyclotron
	Poster MOPA45 [1.434 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA45
About •	Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 12 September 2022
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MOPA59	Prediction of Gaseous Breakdown for Plasma Cleaning of RF Cavities	simulation, cavity, plasma, electronics	174
	S.A. Ahmed Ansys, Inc., Canonsburg, USA
	The quest for a high accelerating gradient in superconducting radio frequency cavity attracted scientists to adopt the plasma cleaning technology. Generating an efficient plasma inside a complex cavity structure for a desired frequency, gas types, and pressure for a given temperature is a challenge. The onset of discharge can be obtained from the well-known Paschen curve. Setting up an experiment is expensive and time-consuming, which may lead to a significant delay in the project. A high-fidelity computer simulation, modeling an arbitrary geometry and tracking the Paschen curve in a complex electromagnetic environment is therefore necessary. Ansys HFSS through its Finite Element Mesh (FEM) for the full-wave EM simulations combined with the electron impact ionization of gases enables the successful prediction of plasma breakdown for an arbitrary configuration for a wide frequency band and variety of gases. A comprehensive study will be demonstrated at the conference. The author like to thank Robert Chao for the valuable discussions and his efforts in developing this capability in the Ansys Electronics Desktop.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA59
About •	Received ※ 01 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 19 August 2022
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MOPA60	HFSS Enables Multipaction Analysis of High Power RF/Microwave Components	multipactoring, simulation, cavity, vacuum	176
	S.A. Ahmed Ansys, Inc., Canonsburg, USA
	The radiofrequency (RF) components in particle accelerators operated under a vacuum and driven by high RF power may be prone to electron multipaction ’ an RF triggered electron resonance phenomenon causing malfunction or complete breakdown. Therefore, exploring the design challenges of vacuum RF windows, cavities, and other devices for the electron multipaction becomes necessary. Setting up an experiment to mitigate the failure of RF devices is expensive and time-consuming, which may cause a significant delay in the project. Therefore, a high-fidelity computer simulation modeling the arbitrary geometry and tracking the particles (electrons) in a complex electromagnetic environment is desirable. Ansys HFSS through Finite Element Mesh (FEM) for the full-wave RF simulation combined with the particle-in-cell (PIC) technique for tracking particles in EM fields; enables the engineers/physicist successful prediction of system failure against the electron multipaction. This paper will demonstrate the workflow of the HFSS multipaction analysis. The author like to thank Robert Chao for the valuable discussions and his efforts in developing this capability in the Ansys Electronics Desktop.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA60
About •	Received ※ 03 August 2022 — Revised ※ 13 August 2022 — Accepted ※ 26 August 2022 — Issue date ※ 06 October 2022
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MOPA69	Adjoint Optimization Applied to Flat to Round Transformers	solenoid, quadrupole, lattice, space-charge	199
	T.M. Antonsen, B.L. Beaudoin, S. Bernal, L. Dovlatyan, I. Haber, P.G. O’Shea, D.F. Sutter UMD, College Park, Maryland, USA
	Funding: This work was supported by DOE-HEP Awards No. DESC0010301 and DESC0022009 We present the numerical optimization, using adjoint techniques, of Flat-to-Round (FTR) transformers operating in the strong self-field limit. FTRs transform an unmagnetized beam that has a high aspect ratio, elliptical spatial cross section, to a round beam in a solenoidal magnetic field. In its simplest form the flat to round conversion is accomplished with a triplet of quadrupoles, and a solenoid. FTR transformers have multiple applications in beam physics research, including manipulating electron beams to cool co-propagating hadron beams. Parameters that can be varied to optimize the FTR conversion are the positions and strengths of the four magnet elements, including the orientations and axial profiles of the quadrupoles and the axial profile and strength of the solenoid’s magnetic field. The adjoint method we employ [1] allows for optimization of the lattice with a minimum computational effort including self-fields. The present model is based on a moment description of the beam. However, the generalization to a particle description will be presented. The optimized designs presented here will be tested in experiments under construction at the University of Maryland. [1] Optimization of Flat to Round Transformers with self-fields using adjoint techniques, L. Dovlatyan, B. Beaudoin, S. Bernal, I. Haber, D. Sutter and TMA, PhysRevAccelBeams.25.044002 (2022).
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA69
About •	Received ※ 03 August 2022 — Revised ※ 25 September 2022 — Accepted ※ 05 December 2022 — Issue date ※ 05 December 2022
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MOPA70	Film Dosimetry Characterization of the Research Linac at the University of Maryland	linac, radiation, vacuum, experiment	203
	A.S. Johnson, L.T. Gilde, M.K. Hottinger, T.W. Koeth UMD, College Park, Maryland, USA
	A heavily modified Varian linac was installed as part of the University of Maryland Radiation Facilities in the early 1980s. The electron linac was initially used for materials testing and pulsed radiolysis. Overtime, diagnostics such as a spectrometer magnet and scintillator screens have been removed, limiting the ability to describe the electron beam. The beamline is currently configured with a thin titanium window to allow the electrons to escape the vacuum region and interact with samples in air. A calibrated film dosimetry system was used to characterize the transverse beam dimensions and uniformity in air. The results of these experimental measurements will be described in this paper.
	Poster MOPA70 [3.423 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA70
About •	Received ※ 27 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 20 August 2022
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MOPA72	Preliminary Tests and Beam Dynamics Simulations of a Straight-Merger Beamline	dipole, experiment, simulation, cavity	206
	A.A. Al Marzouk, P. Piot, T. Xu Northern Illinois University, DeKalb, Illinois, USA S.V. Benson, K.E. Deitrick, J. Guo, A. Hutton, G.-T. Park, S. Wang JLab, Newport News, Virginia, USA D.S. Doran, G. Ha, P. Piot, J.G. Power, C. Whiteford, E.E. Wisniewski ANL, Lemont, Illinois, USA C.E. Mitchell, J. Qiang, R.D. Ryne LBNL, Berkeley, California, USA
	Funding: NSF award PHY-1549132 to Cornell University and NIU, U.S. DOE contract DE-AC02-06CH11357 with ANL and DE-AC05-06OR23177 with JLAB. Beamlines capable of merging beams with different energies are critical to many applications related to advanced accelerator concepts and energy-recovery linacs (ERLs). In an ERL, a low-energy "fresh" bright bunch is generally injected into a superconducting linac for acceleration using the fields established by a decelerated "spent" beam traveling on the same axis. A straight-merger system composed of a selecting cavity with a superimposed dipole magnet was proposed and recently test at AWA. This paper reports on the experimental results obtained so far along with detailed beam dynamics investigations of the merger concept and its ability to conserve the beam brightness associated with the fresh bunch.
	Poster MOPA72 [1.659 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA72
About •	Received ※ 11 August 2022 — Accepted ※ 13 August 2022 — Issue date ※ 02 October 2022
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MOPA74	Design of a W-Band Corrugated Waveguide for Structure Wakefield Acceleration	wakefield, GUI, acceleration, accelerating-gradient	210
	B. Leung, X. Lu, C.L. Phillips, P. Piot Northern Illinois University, DeKalb, Illinois, USA D.S. Doran, X. Lu, P. Piot, J.G. Power ANL, Lemont, Illinois, USA
	Current research on structure wakefield acceleration aims to develop radio-frequency structures that can produce high gradients, with work in the sub-terahertz regime being particularly interesting because of the potential to create more compact and economical accelerators. Metallic corrugated waveguides at sub-terahertz frequencies are one such structure. We have designed a W-band corrugated waveguide for a collinear wakefield acceleration experiment at the Argonne Wakefield Accelerator (AWA). Using the CST Studio Suite, we have optimized the structure for the maximum achievable gradient in the wakefield from a nominal AWA electron bunch at 65 MeV. Simulation results from different solvers of CST were benchmarked with each other, with analytical models, and with another simulation code, ECHO. We are investigating the mechanical design, suitable fabrication technologies, and the possibility to apply advanced bunch shaping techniques to improve the structure performance.
	Poster MOPA74 [1.518 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA74
About •	Received ※ 30 July 2022 — Revised ※ 03 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 26 August 2022
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MOPA76	Wakefield Modeling in Sub-THz Dielectric-Lined Waveguides	wakefield, simulation, GUI, experiment	218
	C.L. Phillips, B. Leung, X. Lu, P. Piot Northern Illinois University, DeKalb, Illinois, USA
	Dielectric-lined waveguides have been extensively studied to potentially support high-gradient acceleration in beam-driven dielectric wakefield acceleration (DWFA) and for beam manipulations. In this paper, we investigate the wakefield generated by a relativistic bunch passing through a dielectric waveguide with different transverse sections. We specifically consider the case of a structure consisting of two dielectric slabs, along with rectangular and square structures. Numerical simulations performed with the fine-difference time-domain of the WarpX program reveal some interesting features of the transverse wake and a possible experiment at the Argonne Wakefield Accelerator (AWA) is proposed.
	Poster MOPA76 [1.294 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA76
About •	Received ※ 12 August 2022 — Accepted ※ 13 August 2022 — Issue date ※ 12 September 2022
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MOPA78	Temporally-Shaped Ultraviolet Pulses for Tailored Bunch Generation at Argonne Wakefield Accelerator	laser, controls, wakefield, cathode	222
	T. Xu, P. Piot Northern Illinois University, DeKalb, Illinois, USA S. Carbajo UCLA, Los Angeles, California, USA S. Carbajo, R.A. Lemons SLAC, Menlo Park, California, USA P. Piot ANL, Lemont, Illinois, USA
	Photocathode laser shaping is an appealing technique to generate tailored electron bunches due to its versatility and simplicity. Most photocathodes require photon energies exceeding the nominal photon energy produced by the lasing medium. A common setup consists of an infrared (IR) laser system with nonlinear frequency conversion to the ultraviolet (UV). In this work, we present the numerical modeling of a temporal shaping technique capable of producing electron bunches with linearly-ramped current profiles for application to collinear wakefield accelerators. Specifically, we show that controlling higher-order dispersion terms associated with the IR pulse provides some control over the UV temporal shape. Beam dynamics simulation of an electron-bunch shaping experiment at the Argonne Wakefield Accelerator is presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA78
About •	Received ※ 01 August 2022 — Revised ※ 06 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 31 August 2022
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MOPA80	Design Study for Non-Intercepting Gas-Sheet Profile Monitor at FRIB	photon, heavy-ion, detector, simulation	229
	A. Lokey, S.M. Lidia FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the US Department of Energy, Office of Science, High Energy Physics under Cooperative Agreement award number DE-SC0018362 and Michigan State University. Non-invasive profile monitors offer a significant advantage for continuous, online monitoring of transverse beam profile and tuning of beam parameters during operation. This is due to both the non-destructive nature of the measurement and the unique feature that some monitors have of being able to determine both transverse profiles in one measurement [1]. One method of interest for making this measurement is the use of a thin gas curtain, which intercepts the beam and generates both ions and photons, which can be collected at a detector situated perpendicular to the gas sheet. This study will investigate the requirements for developing such a measurement device for use at the Facility for Rare Isotope Beams (FRIB), which produces high-intensity, multi charge state, heavy ion beams. Included will be an initial design specifications and an analysis of alternatives between ionization and beam-induced fluorescence measurement techniques for acquiring signal from the gas sheet. [1] I. Yamada, M. Wada, K. Moriya, et al, "High-intensity beam profile measurement using a gas sheet monitor by beam induced fluorescence detection," Phys. Rev. Accel. Beams 24, 042801, 2021.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA80
About •	Received ※ 03 August 2022 — Revised ※ 06 August 2022 — Accepted ※ 06 September 2022 — Issue date ※ 07 October 2022
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MOPA85	Design of a 185.7 MHz Superconducting RF Photoinjector Quarter-Wave Resonator for the LCLS-II-HE Low Emittance Injector	cavity, SRF, gun, cathode	245
	S.H. Kim, W. Hartung, T. Konomi, S.J. Miller, M.S. Patil, J.T. Popielarski, K. Saito, T. Xu, T. Xu FRIB, East Lansing, Michigan, USA C. Adolphsen, L. Ge, F. Ji, J.W. Lewellen, L. Xiao SLAC, Menlo Park, California, USA M.P. Kelly, T.B. Petersen, P. Piot ANL, Lemont, Illinois, USA P. Piot Northern Illinois University, DeKalb, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy Contract DE-AC02-76SF00515. A 185.7 MHz superconducting quarter-wave resonator (QWR) was designed for the low emittance injector of the Linac Coherent Light Source high energy upgrade (LCLS-II-HE). The cavity was designed to minimize the risk of cathode efficiency degradation due to multipacting or field emission and to operate with a high RF electric field at the cathode for low electron-beam emittance. Cavity design features include: (1) shaping of the cavity wall to reduce the strength of the low-field coaxial multipacting barrier; (2) four ports for electropolishing and high-pressure water rinsing; and (3) a fundamental power coupler (FPC) port located away from the accelerating gap. The design is oriented toward minimizing the risk of particulate contamination and avoid harmful dipole components in the RF field. The ANL 162 MHz FPC design for PIP-II is being adapted for the gun cavity. We will present the RF design of the cavity integrated with the FPC.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA85
About •	Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 30 August 2022
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MOPA86	Conditioning of Low-Field Multipacting Barriers in Superconducting Quarter-Wave Resonators	cavity, coupling, multipactoring, cryomodule	249
	S.H. Kim, W. Chang, W. Hartung, J.T. Popielarski, T. Xu FRIB, East Lansing, Michigan, USA
	Funding: This is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University. Multipacting (MP) barriers are typically observed at very low RF amplitude, at a field 2 to 3 orders of magnitude below the operating gradient, in low-frequency (<~100 MHz), quarter-wave resonators (QWRs). Such barriers may be troublesome, as RF conditioning with a fundamental power coupler (FPC) of typical coupling strength (external Q = 10⁶ to 10⁷) is generally difficult. For the FRIB \beta = 0.085 QWRs (80.5 MHz), the low barrier is observed at an accelerating gradient (E_acc) of ~10 kV/m; the operating E_acc is 5.6 MV/m. Theoretical and simulation studies suggested that the conditioning is difficult due to the relatively low RF power dissipated into multipacting rather than being a problem of the low barrier being stronger than other barriers. We developed a single-stub coaxial FPC matching element for external adjustment of the external Q by one order of magnitude. The matching element provided a significant reduction in the time to condition the low barrier. We will present theoretical and simulation studies of the low MP barrier and experimental results on MP conditioning with the single-stub FPC matching element.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA86
About •	Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 21 August 2022
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MOPA89	RHIC Electron Beam Cooling Analysis Using Principle Component and Autoencoder Analysis	luminosity, ECR, network, beam-cooling	260
	A.D. Tran, Y. Hao FRIB, East Lansing, Michigan, USA X. Gu BNL, Upton, New York, USA
	Funding: Work supported by the US Department of Energy under contract No. DE-AC02-98CH10886. Principal component analysis and autoencoder analysis were used to analyze the experimental data of RHIC operation with low energy RHIC electron cooling (LEReC). This is unsupervised learning which includes electron beam settings and observable during operation. Both analyses were used to gauge the dimensional reducibility of the data and to understand which features are important to beam cooling.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA89
About •	Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 12 August 2022
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TUXD4	Analysis Methods for Electron Radiography Based on Laser-Plasma Accelerators	laser, plasma, target, experiment	274
	G.M. Bruhaug, G.W. Collins, H.G. Rinderknecht, J.R. Rygg, J.L. Shaw, M.S. Wei LLE, Rochester, New York, USA M.S. Freeman, F.E. Merrill, L.P. Neukirch, C. Wilde LANL, Los Alamos, New Mexico, USA
	Funding: DOE National Nuclear Security Administration under Award Number DE-NA0003856 DOE under Awards DE-SC00215057 University of Rochester New York State Energy Research and Development Authority Analysis methods are presented for determining the res-olution of both contact and projected electron radiography based on a laser-plasma accelerator. A means to determine the field strength of the electric/magnetic fields generated when a laser is incident on an object of interest is also outlined. Broad radiography results are reported and future plans for the diagnostic technique are outlined.
	Slides TUXD4 [12.157 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUXD4
About •	Received ※ 02 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 03 September 2022
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TUXD6	Dual Radiofrequency Cavity Based Monochromatization for High Resolution Electron Energy Loss Spectroscopy	cavity, cathode, simulation, space-charge	278
	A.V. Kulkarni, P.E. Denham, A. Kogar, P. Musumeci UCLA, Los Angeles, USA
	Reducing the energy spread of electron beams can enable breakthrough advances in electron energy loss spectroscopic investigations of solid state samples where characteristic excitations typically have energy scales on the order of meV. In conventional electron sources the energy spread is limited by the emission process and typically on the order of a fraction of an eV. State-of-the-art energy resolution can only be achieved after significant losses in the monochromatization process. Here we propose to take advantage of photoemission from ultrashort laser pulses (~40 fs) so that after a longitudinal phase space manipulation that trades pulse duration for energy spread, the energy spread can be reduced by more than one order of magnitude. The scheme uses two RF cavities to accomplish this goal and can be implemented on a relatively short (~ 1m) beamline. Analytical predictions and results of 3D self consistent beam dynamics simulations are presented to support the findings.
	Slides TUXD6 [1.461 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUXD6
About •	Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 18 August 2022
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TUYD3	The Quest for the Perfect Cathode	cathode, gun, emittance, photon	281
	J.W. Lewellen, J. Smedley, T. Vecchione SLAC, Menlo Park, California, USA D. Filippetto LBNL, Berkeley, California, USA S.S. Karkare Arizona State University, Tempe, USA J.M. Maxson Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA P. Musumeci UCLA, Los Angeles, California, USA
	Funding: U.S. Department of Energy. The next generation of free electron lasers will be the first to see the performance of the laser strongly dependent on the materials properties of the photocathode. A new injector proposed for the LCLS-II HE is an example of this revolution, with the goal of increasing the photon energy achievable by LCLS-II to over 20 keV. We must now ask, what is the optimal cathode, temperature, and laser combination to enable this injector? There are many competing requirements. The cathode must be robust enough to operate in a superconducting injector, and must not cause contamination of the injector. It must achieve sufficient charge at high repetition rate, while minimizing the emittance. The wavelength chosen must minimize mean transverse energy while maintaining tolerable levels of multi-photon emission. The cathode must be capable of operating at high (~30 MV/m) gradient, which puts limits on both surface roughness and field emission. This presentation will discuss the trade space for such a cathode/laser combination, and detail a new collaborative program among a variety of institutions to investigate it.
	Slides TUYD3 [1.632 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYD3
About •	Received ※ 02 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 14 August 2022 — Issue date ※ 26 September 2022
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TUYD4	Towards High Brightness from Plasmon-Enhanced Photoemitters	cathode, laser, interface, emittance	285
	C.M. Pierce, I.V. Bazarov, J.M. Maxson Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA D.B. Durham, D. Filippetto, F. Riminucci LBNL, Berkeley, USA A.H. Kachwala, S.S. Karkare Arizona State University, Tempe, USA A. Minor UC Berkeley, Berkeley, California, USA
	Funding: This work is supported by DOE BES Contract No. DE-AC02-05CH11231. C.P. acknowledges NSF Award PHY-1549132 (CBB) and the US DOE SCGSR program. DD was supported by NSF Grant No. DMR-1548924 (STROBE). Plasmonic cathodes, whose nanoscale features may locally enhance optical energy from the driving laser trapped at the vacuum interface, have emerged as a promising technology for improving the brightness of metal cathodes. A six orders of magnitude improvement [1] in the non-linear yield of metals has been experimentally demonstrated through this type of nanopatterning. Further, nanoscale lens structures may focus light below its free-space wavelength offering multiphoton photoemission from a region near 10 times smaller [2] than that achievable in typical photoinjectors. In this proceeding, we report on our efforts to characterize the brightness of two plasmonic cathode concepts: a spiral lens and a nanogroove array. We demonstrate an ability to engineer and fabricate nanoscale patterned cathodes by comparing their optical properties with those computed with a finite difference time domain (FDTD) code. The emittance and nonlinear yield of the cathodes are measured under ultrafast laser irradiation. Finally, prospects of this technology for the control and acceleration of charged particle beams are discussed. [1] Polyakov, A., et al. (2013). Physical Review Letters, 110(7), 076802. [2] Durham, D. B., et al. (2019). Physical Review Applied, 12(5), 054057.
	Slides TUYD4 [7.160 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYD4
About •	Received ※ 05 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 13 September 2022
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TUYD5	Epitaxial Alkali-Antimonide Photocathodes on Lattice-matched Substrates	cathode, ECR, laser, lattice	289
	P. Saha, S.S. Karkare Arizona State University, Tempe, USA E. Echeverria, A. Galdi, J.M. Maxson, C.A. Pennington Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA E.J. Montgomery, S. Poddar Euclid Beamlabs, Bolingbrook, USA
	Alkali-antimonides photocathodes, characterized by high quantum efficiency (QE) and low mean transverse energy (MTE) in the visible range of spectrum, are excellent candidates for electron sources to drive X-ray Free Electron Lasers (XFEL) and Ultrafast Electron Diffraction (UED). A key figure of merit for these applications is the electron beam brightness, which is inversely proportional to MTE. MTE can be limited by nanoscale surface roughness. Recently, we have demonstrated physically and chemically smooth Cs₃Sb cathodes on Strontium Titanate (STO) substrates grown via co-deposition technique. Such flat cathodes could result from a more ordered growth. In this paper, we present RHEED data of co-deposited Cs₃Sb cathodes on STO. Efforts to achieve epitaxial growth of Cs₃Sb on STO are then demonstrated via RHEED. We find that films grown epitaxially on substrates like STO and SiC (previously used to achieve single crystalline Cs₃Sb) exhibit QE higher than the polycrystalline Cs₃Sb cathodes, by an order of magnitude below photoemission threshold. Given the larger QE, lower laser fluence could be used to extract high charge densities, thereby leading to enhanced beam brightness.
	Slides TUYD5 [2.088 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYD5
About •	Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 07 September 2022
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TUYD6	Design of a 200 kV DC Cryocooled Photoemission Gun for Photocathode Investigations	cathode, gun, MMI, cryogenics	292
	G.S. Gevorkyan, T.J. Hanks, A.H. Kachwala, S.S. Karkare, C.J. Knill, C.A. Sarabia Cardenas Arizona State University, Tempe, USA
	Funding: This work was supported by the U.S. National Science Foundation under Award No. PHY-1549132, the Center for Bright Beams, and the DOE under Grant No. DE-SC0021092. We present the first results of the commissioning of the 200 kV DC electron gun with a cryogenically cooled cathode at Arizona State University. The gun is specifically designed for studying a wide variety of novel cathode materials including single crystalline and epitaxially grown materials at 30 K temperatures to obtain the lowest possible intrinsic emittance of UED and XFEL applications [1]. We will present the measurements of the cryogenic performance of the gun and the first high voltage commissioning results. [1] G. S. Gevorkyan et. al., Proc. of NAPAC19 MOPLM16 (2019)
	Slides TUYD6 [12.632 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYD6
About •	Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 29 September 2022
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TUZD1	The Electron-Positron Future Circular Collider (FCC-ee)	collider, operation, luminosity, booster	315
	F. Zimmermann, M. Benedikt CERN, Meyrin, Switzerland K. Oide DPNC, Genève, Switzerland T.O. Raubenheimer SLAC, Menlo Park, California, USA
	Funding: Work supported by the European Union’s H2020 Framework Programme under grant agreement no.~951754 (FCCIS). The Future Circular electron-positron Collider (FCC-ee) is aimed at studying the Z and W bosons, the Higgs, and top quark with extremely high luminosity and good energy efficiency. Responding to a request from the 2020 Update of the European Strategy for Particle Physics, in 2021 the CERN Council has launched the FCC Feasibility Study to examine the detailed implementation of such a collider. This FCC Feasibility Study will be completed by the end of 2025 and its results be presented to the next Update of the European Strategy for Particle Physics expected in 2026/27.
	Slides TUZD1 [10.072 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZD1
About •	Received ※ 03 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 21 August 2022 — Issue date ※ 02 September 2022
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TUZD3	Ultimate Limits of Future Colliders	collider, luminosity, acceleration, factory	321
	M. Bai SLAC, Menlo Park, California, USA V.D. Shiltsev Fermilab, Batavia, Illinois, USA F. Zimmermann CERN, Meyrin, Switzerland
	With seven operational colliders in the world and two under construction, the international particle physics community not only actively explores options for the next facilities for detailed studies of the Higgs/electroweak physics and beyond-the-LHC energy frontier, but seeks a clear picture of the limits of the colliding beams method. In this paper, we try to consolidate various recent efforts in identifying physics limits of colliders in conjunction with societal sustainability, and share our thoughts about the perspective of reaching the ultimate quantum limit.
	Slides TUZD3 [3.848 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZD3
About •	Received ※ 25 July 2022 — Revised ※ 03 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 30 August 2022
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TUZD5	Experience and Challenges with Electron Cooling of Colliding Ion Beams in RHIC	operation, collider, cathode, emittance	325
	A.V. Fedotov, X. Gu, D. Kayran, J. Kewisch, S. Seletskiy BNL, Upton, New York, USA
	Funding: Work supported by the U.S. Department of Energy. Electron cooling of ion beams employing rf-accelerated electron bunches was successfully used for the RHIC physics program in 2020 and 2021 and was essential in achieving the required luminosity goals. This presentation will summarize experience and challenges with electron cooling of colliding ion beams in RHIC. We also outline ongoing studies using rf-based electron cooler LEReC.
	Slides TUZD5 [1.373 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZD5
About •	Received ※ 02 August 2022 — Accepted ※ 04 August 2022 — Issue date ※ 14 September 2022
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TUZE1	Experimental Phase-Space Tracking of a Single Electron in a Storage Ring	betatron, photon, synchrotron, experiment	329
	A.L. Romanov, J.K. Santucci, G. Stancari, A. Valishev Fermilab, Batavia, Illinois, USA
	This paper presents the results of the first ever experimental tracking of the betatron and synchrotron phases for a single electron in the Fermilab’s IOTA ring. The reported technology makes it is possible to fully track a single electron in a storage ring, which requires tracking of amplitudes and phases for both, slow synchrotron and fast betatron oscillations.
	Slides TUZE1 [3.600 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZE1
About •	Received ※ 08 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 21 August 2022 — Issue date ※ 27 August 2022
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TUZE4	Particle-in-Cell Simulations of High Current Density Electron Beams in the Scorpius Linear Induction Accelerator	simulation, emittance, plasma, induction	339
	S.E. Clark, Y.-J. Chen, J. Ellsworth, A.T. Fetterman, C.N. Melton, W.D. Stem LLNL, Livermore, USA
	Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Particle-in-cell (PIC) simulations of a high current density (I > 1 kA), and highly relativistic electron beam (E ~ 2-20 MeV) in the Scorpius Linear Induction Accelerator (LIA) are presented. The simulation set consists of a 3D electrostatic/magnetostatic simulation coupled to a 2D XY slice solver that propagates the beam through the proposed accelerator lattice for Scorpius, a next-generation flash X-ray radiography source. These simulations focus on the growth of azimuthal modes in the beam (e.g. Diocotron instability) that arise when physical ring distributions manifest in the beam either due to electron optics or solenoidal focusing and transport. The saturation mechanism appears to lead to the generation of halo particles and conversion down to lower mode numbers as the width of the ring distribution increases. The mode growth and saturation can contribute to the generation of hot spots on the target as well possible azimuthal asymmetries in the radiograph. Simulation results are compared to linear theory and tuning parameters are investigated to mitigate the growth of azimuthal modes in the Scorpius electron beam. * LLNL-ABS-830595, Approved for public release. Distribution Unlimited.
	Slides TUZE4 [4.305 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZE4
About •	Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 21 September 2022
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TUZE5	Studies of Ion Beam Heating by Electron Beams	emittance, experiment, gun, solenoid	343
	S. Seletskiy, A.V. Fedotov, D. Kayran BNL, Upton, New York, USA
	Presence of an electron beam created by either electron coolers or electron lenses in an ion storage ring is associated with an unwanted emittance growth (heating) of the ion bunches. In this paper we report experimental studies of the electron-ion heating in the Low Energy RHIC electron Cooler (LEReC).
	Slides TUZE5 [1.368 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZE5
About •	Received ※ 01 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 17 September 2022
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TUPA04	Sheet Electron Probe for Beam Tomography	proton, diagnostics, cathode, simulation	354
	V.G. Dudnikov, M.A. Cummings, G. Dudnikova Muons, Inc, Illinois, USA
	Funding: Supported by DOE SBIR grant # DE-SC0021581. We propose a new approach to electron beam tomography: we will generate a pulsed sheet of electrons. As the ion beam bunches pass through the sheet, they cause distortions in the distribution of sheet electrons arriving at a luminescent screen with a CCD device on the other side of the beam; these sheet electrons are interpreted to give a continuous measurement of the beam profile. The apparatus to generate the sheet beam is a strip cathode, which, compared to the scanning electron beam probe, is smaller, has simpler design and less expensive manufacturing, has better magnetic shielding, has higher sensitivity and higher resolution, has better accuracy of measurement, and has better time resolution.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA04
About •	Received ※ 22 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 10 August 2022
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TUPA11	Magnet System for a Compact Microtron Source	microtron, cavity, extraction, injection	363
	S.A. Kahn, R.J. Abrams, M.A. Cummings, R.P. Johnson, G.M. Kazakevich Muons, Inc, Illinois, USA
	Funding: Work supported in part by U.S. D.O.E. SBIR grant DE-SC0013795. A microtron can be an effective intense electron source. It can use less RF power than a linac to produce a similar energy because the beam will pass through the RF cavity several times. To produce a high-quality low-emittance beam with a microtron requires a magnetic system with a field uniformity $δ B/B<0.001. Field quality for a compact microtron with fewer turns is more difficult to achieve. In this study we describe the magnet for a compact S-band microtron that will achieve the necessary field requirements. The shaping of the magnet poles and shimming of the magnet iron at the outer extent of the poles will be employed to provide field uniformity. The extraction of the beam will be discussed.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA11
About •	Received ※ 04 August 2022 — Revised ※ 14 August 2022 — Accepted ※ 06 September 2022 — Issue date ※ 08 October 2022
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TUPA13	Affordable, Efficient Injection-Locked Magnetrons for Superconducting Cavities	cavity, injection, controls, GUI	366
	M. Popovic, M.A. Cummings, R.P. Johnson, S.A. Kahn, R.R. Lentz, M.L. Neubauer, T. Wynn Muons, Inc, Illinois, USA T. Blassick, J.K. Wessel Richardson Electronics Ltd, Lafox, Illinois, USA
	Funding: DE-SC0022586. Existing magnetrons that are typically used to study methods of control or lifetime improvements for SRF accelerators are built for much different applications such kitchen microwave ovens (1kW, 2.45 GHz) or industrial heating (100 kW, 915 MHz). In this project, Muons, Inc. will work with an industrial partner to develop fast and flexible manufacturing techniques to allow many ideas to be tested for construction variations that enable new phase and amplitude injection locking control methods, longer lifetime, and inexpensive refurbishing resulting in the lowest possible life-cycle costs. In Phase II magnetron sources will be tested on SRF cavities to accelerate an electron beam at JLab. A magnetron operating at 650 MHz will be constructed and tested with our novel patented subcritical voltage operation methods to drive an SRF cavity. The choice of 650 MHz is an optimal frequency for magnetron efficiency. The critical areas of magnetron manufacturing and design affecting life-cycle costs that will be modeled for improvement include: Q_ext, filaments, magnetic field, vane design, and novel control of outgassing.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA13
About •	Received ※ 05 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 23 August 2022
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TUPA14	Fast First-Order Spin Propagation for Spin Matching and Polarization Optimization with Bmad	polarization, quadrupole, lattice, solenoid	369
	J.M. Asimow, G.H. Hoffstaetter, D. Sagan, M.G. Signorelli Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Accurate spin tracking is essential for the simulation and propagation of polarized beams, in which a majority of the particles’ spin point in the same direction. Bmad, an open-sourced library for the simulation of charged particle dynamics, traditionally tracks spin via integrating through each element of a lattice. While exceptionally accurate, this method has the drawback of being slow; at best, the runtime is proportional to the length of the element. By solving the spin transport equation for simple magnet elements, Bmad can reduce this algorithm to constant runtime while maintaining high accuracy. This method, known as "Sprint," enables quicker spin matching and prototyping of lattice designs via Bmad.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA14
About •	Received ※ 30 July 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 24 August 2022
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TUPA21	Hydrodynamic and Beam Dynamic Simulations of Ultra-Low Emittance Whole Beam Dumps in the Advanced Photon Source Storage Ring	simulation, experiment, photon, storage-ring	390
	J.C. Dooling, M. Borland, A.M. Grannan, C.J. Graziani, Y. Lee, R.R. Lindberg, G. Navrotski ANL, Lemont, Illinois, USA N.M. Cook RadiaSoft LLC, Boulder, Colorado, USA D.W. Lee UCSC, Santa Cruz, California, USA
	Funding: Work supported by Accelerator Science and Technology LDRD Project 2021-0119 and the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source Upgrade will use a multi-bend achromatic lattice to reduce vertical and horizontal beam emittances by one- and two-orders of magnitude respectively; in addition operating current will double. The resulting electron beam will be capable of depositing more than 150 MGy on machine protection collimators creating high-energy-density conditions. Work is underway to couple the beam dynamics code Elegant with the particle-matter interaction program MARS and the magnetohydrodynamics code FLASH to model the effects of whole beam dumps on the collimators. Loss distributions from Elegant are input to MARS which provide dose maps to FLASH. We also examine the propagation of downstream shower components after the beam interacts with the collimator. Electrons and positrons are tracked to determine locations of beam loss. Beam dump experiments conducted in the APS storage-ring, generated dose levels as high as 30 MGy resulting in severe damage to the collimator surfaces with melting in the bulk. The deformed collimator surface may lead to beam deposition in unexpected locations. A fan-out kicker is planned to mitigate the effects of whole beam dumps on the collimators.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA21
About •	Received ※ 02 August 2022 — Revised ※ 10 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 10 September 2022
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TUPA28	Update on the Development of a Low-Cost Button BPM Signal Detector at AWA	pick-up, simulation, detector, electronics	409
	W. Liu, G. Chen, D.S. Doran, S.Y. Kim, X. Lu, P. Piot, J.G. Power, C. Whiteford, E.E. Wisniewski ANL, Lemont, Illinois, USA E.E. Wisniewski IIT, Chicago, Illinois, USA
	Funding: Work supported by the US Department of Energy, Office of Science. A single-pulse, high dynamic range, cost-effective BPM signal detector has been on the most wanted list of the Argonne Wakefield Accelerator (AWA) Test Facility for many years. The unique capabilities of the AWA beamline require BPM instrumentation with an unprecedented dynamic range, thus a cost-effective solution could be challenging to design and prototype. With the help of a better circuit model for a button BPM signal source, we are able to do the circuit simulations with more realistic input signals and make predictions much closer to realities. Our most recent design and prototype results are shared in this paper.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA28
About •	Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 09 October 2022
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TUPA32	SCU Ends Configured as Phase Shifter	undulator, simulation, FEL, quadrupole	420
	M.F. Qian ANL, Lemont, Illinois, USA
	Funding: Work supported by LDRD funding from Argonne National Laboratory, provided by the Director, Office of Science, of the U.S. DOE under Contract No. DE-AC02-06CH11357. Dipole correctors and phase shifters are usually needed in the interspace of a permanent magnet (PM)-based undulator array for purposes of beam steering and phase matching when the field strength is changing. Unlike the PM-based undulators, the superconducting undulator (SCU) can change its end field with the help of varying currents in the end coils. By setting the end coil currents the beam-steering and the phase-matching could be realized, thus eliminating the need for standalone correctors and phase shifters, saving the interspace as well as reducing the mechanical complexity of an undulator array. We developed a procedure for determining the SCU end coil currents and verified it by numerical simulations. The procedure as well as the simulation results are described in this paper.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA32
About •	Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 07 September 2022
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TUPA33	Magnetic Field Calculation of Superconducting Undulators for FEL Using Maxwell 3D	undulator, FEL, wiggler, laser	423
	Y. Shiroyanagi, Y. Ivanyushenkov, M. Kasa ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. An ANL-SLAC collaboration is working on design of a planar superconducting undulator (SCU) demonstrator for a FEL. As a part of this project, a SCU magnet prototype is planned to be built and tested. A planar SCU magnet consisting of a 1.0-m-long segment is being designed. Although OPERA is a standard tool for magnetic field calculation, ANSYS Maxwell 3D can also be used for a large and complex geometry. An ANSYS calculated magnetic field was benchmarked with the measured field profile of existing SCUs. This paper presents calculations of magnetic field and field integrals of 0.5-m-long and 1.0-m-long planar SCUs with a new end correction scheme. Then, an external phase shifter is also incorporated into the model. A cross-talk between a phase shifter and SCU magnetic structures is also presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA33
About •	Received ※ 02 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 25 August 2022
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TUPA36	The Advanced Photon Source Linac Extension Area Beamline	gun, linac, photon, lattice	430
	K.P. Wootton, W. Berg, J.M. Byrd, J.C. Dooling, G.I. Fystro, A.H. Lumpkin, Y. Sun, A. Zholents ANL, Lemont, Illinois, USA C.C. Hall RadiaSoft LLC, Boulder, Colorado, USA
	Funding: This research used resources of the Advanced Photon Source, operated for the U.S. Department of Energy Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. The Linac Extension Area at the Advanced Photon Source is a flexible beamline area for testing accelerator components and techniques. Driven by the Advanced Photon Source electron linac equipped with a photocathode RF electron gun, the Linac Extension Area houses a 12 m long beamline. The beamline is furnished with YAG screens, BPMs and a magnetic spectrometer to assist with characterization of beam emittance and energy spread. A 1.4 m long insertion in the middle of the beamline is provided for the installation of a device under test. The beamline is expected to be available soon for testing accelerator components and techniques using round and flat electron beams over an energy range 150-450 MeV. In the present work, we describe this beamline and summarise the main beam parameters.
	Poster TUPA36 [0.892 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA36
About •	Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 19 September 2022
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TUPA38	Sublinear Intensity Response of Cerium-Doped Yttrium Aluminium Garnet Screen with Charge	booster, FEL, linac, storage-ring	437
	K.P. Wootton, A.H. Lumpkin ANL, Lemont, Illinois, USA
	Funding: This research used resources of the Advanced Photon Source, operated for the U.S. Department of Energy Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Swap-out injection to the Advanced Photon Source Upgrade storage ring necessitates the injection of ~17 nC electron bunches at 6 GeV. To aid with machine tune-up and to measure the beam size, diagnostic imaging screens are envisaged at several locations in the beam transport line from the booster synchrotron to the storage ring. As such, it is important to determine whether the response of these screens to charge is linear. In the present work, we examine the effect of sublinear intensity quenching of a Cerium-doped Yttrium-Aluminium-Garnet scintillator screen. A 1.3 megapixel FLIR BlackFly monochrome digital camera was used to image the beam at the scintillator. At 7 GeV beam energy, over the charge densities investigated (<10 fC um^-2), an approximately 10 % reduction of the imaging intensity due to quenching of the scintillator was observed.
	Poster TUPA38 [0.557 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA38
About •	Received ※ 02 August 2022 — Accepted ※ 03 August 2022 — Issue date ※ 09 August 2022
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TUPA41	Applications of Machine Learning in Photo-Cathode Injectors	laser, controls, cathode, network	441
	A. Aslam UNM-ECE, Albuquerque, USA M. Babzien BNL, Upton, New York, USA S. Biedron Element Aero, Chicago, USA
	To configure a photoinjector to reproduce a given electron bunch with the desired characteristics, it is necessary to adjust the operating parameters with high precision. More or less, the fine tunability of the laser parameters are of extreme importance as we try to model further applications of the photoinjector. The laser pulse incident on the photocathode critically affects the electron bunch 3D phase space. Parameters such as the laser pulse transverse shape, total energy, and temporal profile must be controlled independently, any laser pulse variation over both short and long-time scales also requires correction. The ability to produce arbitrary laser intensity distributions enables better control of electron bunch transverse and longitudinal emittance by affecting the space-charge forces throughout the bunch. In an accelerator employing a photoinjector, electron optics in the beamline downstream are used to transport, manipulate, and characterize the electron bunch. The adjustment of the electron optics to achieve a desired electron bunch at the interaction point is a much better understood problem than laser adjustment, so this research emphasizes laser shaping.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA41
About •	Received ※ 30 July 2022 — Revised ※ 12 August 2022 — Accepted ※ 13 August 2022 — Issue date ※ 07 September 2022
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TUPA52	Initial Results of the 201.25 MHz Coaxial Window Test Stand	multipactoring, Windows, vacuum, DTL	458
	T.W. Hall, J.T.M. Lyles, A. Poudel, A.S. Waghmare LANL, Los Alamos, New Mexico, USA
	We have recently commissioned an RF window test stand for the Drift Tube Linear Accelerator (DTL) portion of the Los Alamos Neutron Science Center (LANSCE). The window test stand consists of two RF windows that create a vacuum chamber which allows the windows to be tested to the peak power levels used in the DTL. Initial results clearly indicated multipactoring due to the increase of pressure at specific regions of peak forward power levels. Temperature measured at various azimuthal locations on both windows showed increased multipactor heating on the downstream window versus the upstream window. We present the effect of the titanium nitride coating that is presently applied to windows on both multipactor and window temperature. These results are discussed with respect to their impact on the LANSCE DTL performance.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA52
About •	Received ※ 25 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 07 September 2022
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TUPA53	Modeling of Nonlinear Beam Dynamics via a Novel Particle-Mesh Method and Surrogate Models with Symplectic Neural Networks	simulation, network, radiation, synchrotron-radiation	462
	C.-K. Huang, O. Beznosov, J.W. Burby, B.E. Carlsten, G.A. Dilts, J. Domine, R. Garimella, A. Kim, T.J. Kwan, H.N. Rakotoarivelo, R.W. Robey, B. Shen, Q. Tang LANL, Los Alamos, New Mexico, USA F.Y. Li New Mexico Consortium, Los Alamos, USA
	Funding: Work supported by the LDRD program at Los Alamos National Laboratory and the ASCR SciML program of DOE. The self-consistent nonlinear dynamics of a relativistic charged particle beam, particularly through the interaction with its complete self-fields, is a fundamental problem underpinning many accelerator design issues in high brightness beam applications, as well as the development of advanced accelerators. A novel self-consistent particle-mesh code, CoSyR [1], is developed based on a Lagrangian method for the calculation of the beam particles’ radiation near-fields and associated beam dynamics. Our recent simulations reveal the slice emittance growth in a bend and complex interplay between the longitudinal and transverse dynamics that are not captured in the 1D longitudinal static-state Coherent Synchrotron Radiation (CSR) model. We further show that surrogate models with symplectic neural networks can be trained from simulation data with significant time-savings for the modeling of nonlinear beam dynamics effects. Possibility to extend such surrogate models for the study of spin-orbital coupling is also briefly discussed. [1] C.-K. Huang et al., Nucl. Instruments Methods Phys. Res. Sect. A, vol. 1034, p. 166808, 2022.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA53
About •	Received ※ 25 July 2022 — Revised ※ 03 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 11 August 2022
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TUPA55	Progress Toward Improving Accelerator Performance and Automating Operations with Advanced Analysis Software	diagnostics, operation, cathode, software	465
	J.E. Koglin, J.E. Coleman, M. McKerns, D. Ronquillo, A. Scheinker LANL, Los Alamos, New Mexico, USA
	Funding: Research presented in this conference paper was supported by the Laboratory Directed Research and Development program of Los Alamos National Laboratory under project numbers XXG2, XX8R and XXB6. The penetrating radiography provided by the Dual Axis Radiographic Hydrodynamic Test (DARHT) facility is a key capability in executing a core mission of the Los Alamos National Laboratory (LANL). A new suite of software is being developed in the Python programming language to support operations of the of two DARHT linear induction accelerators (LIAs). Historical data, built as hdf5 data structures for over a decade of operations, are being used to develop automated failure and anomaly detection software and train machine learning models to assist in beam tuning. Adaptive machine learning (AML) that incorporate physics-based models are being designed to use non-invasive diagnostic measurements to address the challenge of time variation in accelerator performance and target density evolution. AML methods are also being developed for experiments that use invasive diagnostics to understand the accelerator behavior at key locations, the results of which will be fed back into the accelerator models. The status and future outlook for these developments will be reported, including how Jupyter notebooks are being used to rapidly deploy these advances as highly-interactive web applications.
	Poster TUPA55 [1.919 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA55
About •	Received ※ 15 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 12 August 2022
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TUPA65	Machine Learning for the LANL Electromagnetic Isotope Separator	controls, dipole, ion-source, feedback	490
	A. Scheinker, K.W. Dudeck, C.P. Leibman LANL, Los Alamos, New Mexico, USA
	Funding: Los Alamos National Laboratory Electromagnetic Isotope Separator Project. The Los Alamos National Laboratory electromagnetic isotope separator (EMIS) utilizes a Freeman ion source to generate beams of various elements which are accelerated to 40 keV and passed through a 75-degree bend using a large dipole magnet with a radius of 1.2 m. The isotope mass differences translate directly to a spread in momentum, dp, relative to the design momentum p0. Momentum spread is converted to spread in the horizontal arrival location dx at a target chamber by the dispersion of the dipole magnet: dx = D(s)dp/p0. By placing a thin slit leading to a collection chamber at a location xc specific isotope mass is isolated by adjusting the dipole magnet strength or the beam energy. The arriving beam current at xc is associated with average isotope atomic mass, giving an isotope mass spectrum I(m) measured in mA. Although the EMIS is a compact system (5 m) setting up and automatically running at an optimal isotope separation profile I(m) profile is challenging due to time-variation of the complex source as well as un-modeled disturbances. We present preliminary results of developing adaptive machine learning-based tools for the EMIS beam and for the accelerator components.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA65
About •	Received ※ 18 July 2022 — Revised ※ 07 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 10 August 2022
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TUPA72	Comparison Study on First Bunch Compressor Schemes by Conventional and Double C-Chicane for MaRIE XFEL	dipole, emittance, FEL, radiation	496
	H. Xu, P.M. Anisimov, L.D. Duffy, Q.R. Marksteiner LANL, Los Alamos, New Mexico, USA
	Funding: Laboratory Directed Research and Development program of Los Alamos National Laboratory, project number 20200287ER. We report our comparison study on the first stage electron bunch compression schemes at 750 MeV using a conventional and a double C-chicane for the X-ray free electron laser (XFEL) under development for the Matter-Radiation Interactions in Extremes (MaRIE) initiative at Los Alamos National Laboratory. Compared to the performance of the conventional C-chicane bunch compressor, the double C-chicane scheme exhibits the capability of utilizing the transverse momentum shift induced by the coherent synchrotron radiation in the second C-chicane to compensate that generated in the first C-chicane, resulting in a compressed electron bunch with minimized transverse momentum shift along the beam. It is also found that the double C-chicane scheme can be designed to significantly better preserve the beam emittance in the course of the bunch compression. This is particularly beneficial for the MaRIE XFEL whose lasing performance critically depends on the preservation of the ultralow beam emittance.
	Poster TUPA72 [1.339 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA72
About •	Received ※ 01 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 15 August 2022
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TUPA73	Design and Low Power Test of an Electron Bunching Enhancer Using Electrostatic Potential Depression	cavity, simulation, gun, experiment	499
	H. Xu, B.E. Carlsten, Q.R. Marksteiner LANL, Los Alamos, New Mexico, USA B.L. Beaudoin, T.W. Koeth, A. Ting UMD, College Park, Maryland, USA
	Funding: This project was supported by the U.S. Department of Energy Office of Science through the Accelerator Stewardship Program. We present our experimental design and low power test results of a structure for the proof-of-principle demonstration of fast increase of the first harmonic current content in a bunched electron beam, using the technique of electrostatic potential depression (EPD). A primarily bunched electron beam from an inductive output tube (IOT) at 710 MHz first enters an idler cavity, where the longitudinal slope of the beam energy distribution is reversed. The beam then transits through an EPD section implemented by a short beam pipe with a negative high voltage bias, inside which the rate of increase of the first harmonic current is significantly enhanced. An output cavity measures the harmonic current developed inside the beam downstream of the EPD section. Low power test results of the idler and the output cavities agree with the theoretical design.
	Poster TUPA73 [1.307 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA73
About •	Received ※ 29 July 2022 — Accepted ※ 03 August 2022 — Issue date ※ 09 August 2022
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TUPA74	Numerical Calculations of Wave Generation from a Bunched Electron Beam in Space	plasma, radiation, simulation, experiment	502
	H. Xu, G.L. Delzanno, L.D. Duffy, Q.R. Marksteiner, G.D. Reeves LANL, Los Alamos, New Mexico, USA
	Funding: This project was supported by the Laboratory Directed Research and Development program of Los Alamos National Laboratory. We present our numerical approach and preliminary results of the calculations of whistler and X-mode wave generation by a bunched electron beam in space. The artificial generation of whistler and X-mode plasma waves in space is among the candidate techniques to accomplish the radiation belt remediation (RBR), in an effort to precipitate energetic electrons towards the atmosphere to reduce their threat to low-Earth orbit satellites. Free-space propagation of an electron pulse in a constant background magnetic field was simulated with the CST particle-in-cell (PIC) solver, with the temporal evolution of the beam recorded. The SpectralPlasmaSolver (SPS) was then modified to use the recorded electron pulse propagation to calculate the real-time plasma waves generated by the beam. SPS simulation results of the wave generation for the upcoming Beam-PIE experiment as well as an ideal bunched electron beam are shown.
	Poster TUPA74 [0.963 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA74
About •	Received ※ 18 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 08 August 2022
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TUPA77	X-Band Harmonic Longitudinal Phase Space Linearization at the PEGASUS Photoinjector	cavity, linac, gun, laser	508
	P.E. Denham, P. Musumeci, A. Ody UCLA, Los Angeles, USA
	Due to the finite bunch length, photoemitted electron beams sample RF-nonlinearities that lead to energy-time correlations along the bunch temporal profile. This is an important effect for all applications where the projected energy spread is important. In particular, for time-resolved single shot electron microscopy, it is critical to keep the beam energy spread below 1·10^-4 to avoid chromatic aberrations in the lenses. Higher harmonic RF cavities can be used to compensate for the RF-induced longitudinal phase space nonlinearities. Start-to-end simulations suggest that this type of compensation can reduce energy spread to the 1·10^-5 level. This work is an experimental study of x-band harmonic linearization of a beam longitudinal phase space at the PEGASUS facility, including developing high-resolution spectrometer diagnostics to verify the scheme.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA77
About •	Received ※ 25 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 10 August 2022
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TUPA81	Design of a High-Power RF Breakdown Test for a Cryocooled C-Band Copper Structure	cavity, cryogenics, GUI, distributed	516
	G.E. Lawler, A. Fukasawa, J.R. Parsons, J.B. Rosenzweig UCLA, Los Angeles, California, USA Z. Li, S.G. Tantawi SLAC, Menlo Park, California, USA A. Mostacci Sapienza University of Rome, Rome, Italy E.I. Simakov, T. Tajima LANL, Los Alamos, New Mexico, USA B. Spataro LNF-INFN, Frascati, Italy
	Funding: This work was supported by the DOE Contract DE-SC0020409. High-gradient RF structures capable of maintaining gradients in excess of 250 MV/m are critical in several concepts for future electron accelerators. Concepts such as the ultra-compact free electron laser (UC-XFEL) and the Cool Copper Collider (C3) plan to obtain these gradients through the cryogenic operation (<77K) of normal conducting copper cavities. Breakdown rates, the most significant gradient limitation, are significantly reduced at these low temperatures, but the precise physics is complex and involves many interacting effects. High-power RF breakdown measurements at cryogenic temperatures are needed at the less explored C-band frequency (5.712 GHz), which is of great interest for the aforementioned concepts. On behalf of a large collaboration of UCLA, SLAC, LANL, and INFN, the first C-band cryogenic breakdown measurements will be made using a LANL RF test infrastructure. The 2-cell geometry designed for testing will be modifications of the distributed coupled reentrant design used to efficiently power the cells while staying below the limiting values of peak surface electric and magnetic fields.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA81
About •	Received ※ 29 July 2022 — Accepted ※ 02 August 2022 — Issue date ※ 08 August 2022
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TUPA83	Derivative-Free Optimization of Multipole Fits to Experimental Wakefield Data	wakefield, simulation, multipole, experiment	523
	N. Majernik, G. Andonian, W.J. Lynn, J.B. Rosenzweig UCLA, Los Angeles, California, USA P. Piot, T. Xu Northern Illinois University, DeKalb, Illinois, USA
	Funding: Department of Energy DE-SC0017648. A method to deduce the transverse self-wakefields acting on a beam, based only on screen images, is introduced. By employing derivative-free optimization, the relatively high-dimensional parameter space can be efficiently explored to determine the multipole components up to the desired order. This technique complements simulations, which are able to directly infer the wakefield composition. It is applied to representative simulation results as a benchmark and also applied to experimental data on skew wake observations from dielectric slab structures.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA83
About •	Received ※ 02 August 2022 — Revised ※ 21 August 2022 — Accepted ※ 26 August 2022 — Issue date ※ 11 September 2022
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TUPA86	Simulations of Nanoblade Cathode Emissions with Image Charge Trapping for Yield and Brightness Analyses	brightness, laser, emittance, scattering	535
	J.I. Mann, G.E. Lawler, J.B. Rosenzweig, B. Wang UCLA, Los Angeles, California, USA T. Arias, J.K. Nangoi Cornell University, Ithaca, New York, USA S.S. Karkare Arizona State University, Tempe, USA
	Funding: National Science Foundation Grant No. PHY-1549132 Laser-induced field emission from nanostructures as a means to create high brightness electron beams has been a continually growing topic of study. Experiments using nanoblade emitters have achieved peak fields upwards of 40 GV/m according to semi-classical analyses, begging further theoretical investigation. A recent paper has provided analytical reductions of the common semi-infinite Jellium system for pulsed incident lasers. We utilize these results to further understand the physics underlying electron rescattering-type emissions. We numerically evaluate this analytical solution to efficiently produce spectra and yield curves. The effect of space-charge trapping at emission may be simply included by directly modifying these spectra. Additionally, we use a self-consistent 1-D time-dependent Schrödinger equation with an image charge potential to study the same system as a more exact, but computationally costly, approach. With these results we may finally investigate the mean transverse energy and beam brightness at the cathode in these extreme regimes.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA86
About •	Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 03 September 2022
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TUPA87	Simulations for the Space Plasma Experiments at the SAMURAI Lab	plasma, simulation, experiment, radiation	539
	P. Manwani, H.S. Ancelin, A. Fukasawa, G.E. Lawler, N. Majernik, B. Naranjo, J.B. Rosenzweig, Y. Sakai, O. Williams UCLA, Los Angeles, California, USA G. Andonian RadiaBeam, Santa Monica, California, USA
	Funding: This work was performed with support of the US Department of Energy under Contract No. DE-SC0017648 and DESC0009914, and the DARPA GRIT Contract 20204571 Plasma wakefield acceleration using the electron linear accelerator test facility, SAMURAI, can be used to study the Jovian electron spectrum due to the high energy spread of the beam after the plasma interaction. The SAMURAI RF facility which is currently being constructed and commissioned at UCLA, is is capable of producing beams with 10 MeV energy, 2 nC charge, and 200 fsec bunch lengths with a 4 um emittance. Particle-in-cell (PIC) simulations are used to study the beam spectrum that would be generated from plasma interaction. Experimental methods and diagnostics are discussed in this paper.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA87
About •	Received ※ 04 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 06 September 2022
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WEXD6	Electron Cloud Measurements in Fermilab Booster	booster, simulation, proton, laser	556
	S.A.K. Wijethunga, J.S. Eldred, E. Pozdeyev, C.-Y. Tan Fermilab, Batavia, Illinois, USA
	Fermilab Booster synchrotron requires an intensity upgrade from 4.5×10¹² to 6.5×10¹² protons per pulse as a part of Fermilab’s Proton Improvement Plan-II (PIP-II). One of the factors which may limit the high-intensity performance is the fast transverse instabilities caused by electron cloud effects. According to the experience in the Recycler, the electron cloud gradually builds up over multiple turns in the combined function magnets and can reach final intensities orders of magnitude greater than in a pure dipole. Since the Booster synchrotron also incorporates combined function magnets, it is important to discover any existence of an electron cloud. And if it does, its effects on the PIP-II era Booster and whether mitigating techniques are required. As the first step, the presence or absence of the electron cloud was investigated using a gap technique. This paper presents experimental details and observations of the bunch-by-bunch tune shifts of beams with various bunch train structures at low and high intensities and simulation results conducted using PyECLOUD software.
	Slides WEXD6 [4.483 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEXD6
About •	Received ※ 02 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 21 August 2022 — Issue date ※ 09 September 2022
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WEYD3	Positron Acceleration in Linear, Moderately Non-Linear and Non-Linear Plasma Wakefields	positron, plasma, collider, emittance	560
	G.J. Cao, E. Adli University of Oslo, Oslo, Norway S. Corde LOA, Palaiseau, France S.J. Gessner SLAC, Menlo Park, California, USA
	Accelerating particles to high energies with high efficiency and beam quality is crucial in developing accelerator technologies. The plasma acceleration technique, providing unprecedented high gradients, is considered as a promising future technology. While important progress has been made in plasma-based electron acceleration in recent years, identifying a reliable acceleration technique for the positron counterpart would pave the way to a linear e⁺e⁻ collider for high-energy physics applications. In this work, we show further studies of positron beam quality in moderately non-linear (MNL)* plasma wakefields. With a positron bunch of initial energy 1 GeV, emittance preservation can be achieved in optimised scenarios at 2.38 mm’mrad. In parallel, asymmetric beam collisions at the interaction point (IP) are studied to evaluate the current luminosity reach and provide insight to improvements required for positron acceleration in plasma. It is necessary to scale down the emittance of the positron bunch. In the MNL regime, a positron beam with 238 ’m’mrad level emittance implies compromise in charge or necessity for ultra-short bunches. * "Efficiency and beam quality for positron acceleration in loaded plasma wakefields",C. S. Hue, G. J. Cao, et.al Phys. Rev. Research 3, 043063
	Slides WEYD3 [3.635 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEYD3
About •	Received ※ 01 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 24 August 2022
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WEYE4	Electron Cloud Simulations in the Fermilab Recycler	simulation, software, proton, optics	581
	A.P. Schreckenberger University of Illinois at Urbana-Champaign, Urbana, USA R. Ainsworth Fermilab, Batavia, Illinois, USA
	We present a simulation study to characterize the stability region of the Fermilab Recycler Ring in the context of secondary emission yield (SEY). Interactions between electrons and beam pipe material can produce electron clouds that jeopardize beam stability in certain focusing configurations. Such an instability was documented in the Recycler, and the work presented here reflects improvements to better understand that finding. We incorporated the Furman-Pivi Model into a PyECLOUD analysis, and we determined the instability threshold given various bunch lengths, beam intensities, SEY magnitudes, and model parameters.
	Slides WEYE4 [2.096 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEYE4
About •	Received ※ 01 August 2022 — Revised ※ 06 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 30 September 2022
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WEYE6	Thermionic Sources for Electron Cooling at IOTA	vacuum, cathode, proton, space-charge	588
	M.K. Bossard, Y.K. Kim University of Chicago, Chicago, Illinois, USA N. Banerjee, J.A. Brandt Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA B.L. Cathey, S. Nagaitsev, G. Stancari Fermilab, Batavia, Illinois, USA M.A. Krieg Saint Olaf College, Northfield, MN, USA
	We are planning a new electron cooling experiment at the Integrable Optics Test Accelerator (IOTA) at Fermilab for cooling ~2.5 MeV protons in the presence of intense space-charge. Here we present the simulations and design of a thermionic electron source for cooling at IOTA. We particularly discuss parameters of the thermionic source electrodes, as well as the simulation results. We also present a new electron source test-stand at the University of Chicago, which will be used to test the new thermionic electron source, as well as other electron sources. In addition, we discuss results from analyzing the test stand operations with a currently existing electron source. Furthermore, we present future steps for the test stand as well as production and commissioning of the thermionic source at IOTA.
	Slides WEYE6 [3.182 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEYE6
About •	Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 28 August 2022
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WEZD1	ARDAP’s Perspective on Accelerator Technology R&D in the U.S.	operation, collider, laser, controls	592
	B.E. Carlsten, E.R. Colby, R.A. Marsh, M. White ARDAP, Washington, USA
	DOE operates several particle accelerator facilities and is planning several new forward-leaning accelerator facilities over the next decade or two. These new facilities will focus on discovery science research and fulfilling other core DOE missions. Near and mid-term examples include PIP-II and FACET-II (for High Energy Physics); LCLS-II, SNS-PPU, APS-U, and ALS-U (for Basic Energy Sciences); FRIB (for Nuclear Physics); NSTX-U and MPEX (for Fusion Energy Sciences); and Scorpius (for NNSA). Longer-term examples may include future colliders, the SNS-STS, LCLS-II HE, and EIC. In addition to domestic facilities, DOE’s Office of Science (SC) also contributes to several international efforts. Together, these new facilities constitute a multibillion-dollar construction and operations investment. To be successful, they will require advances in state-of-the-art accelerator technologies. They will also require the National Laboratories to procure a variety of accelerator components. This paper summarizes how DOE is working to address these upcoming R&D and accelerator component production needs through its new office of Accelerator R&D and Production (ARDAP).
	Slides WEZD1 [2.310 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEZD1
About •	Received ※ 05 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 19 August 2022
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Paper

Title

Other Keywords

Page

MOODE1

Applications of Particle Accelerators

linac, site, neutron, target

1

M. Uesaka
JAEC, Tokyo, Japan

Applications of particle accelerators amid global policies of carbon neutrality and economic security. are reviewed. Downsizing of high energy large scaled accelerators by advanced technologies enables a variety of medical and industrial uses. One of the highlights is upgrade of sustainable supply chain of medical radioisotopes by the best mix of research reactors and accelerators. 99Mo/99mTc for diagnosis are going to be produced by low enriched U reactor and proton-cyclotron, electron rhodotron and electron linac. Moreover, the theranostics by 177Lu (beta) and 211At/225Ac (alpha) are going to be realized. Proton-cyclotron and electron linac are expected to produce them soon. This new affordable radiation therapy should play an important role in the IAEA project of Rays of Hopes. Next, proof-of-principle trails of on-site bridge inspection of the portable X-band (9.3 GHz) electron linac X-ray/neutron sources are under way. The technical guideline for the practical inspection is to be formed in a couple of years. Ultimate micro-accelerator for microbeam applications is dielectric laser accelerator, such as ACHIP project. Updated projects and results are also introduced.

Slides MOODE1 [3.065 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOODE1

About •

Received ※ 02 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 11 August 2022

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MOYD4

Model Parameters Determination in EIC Strong-Strong Simulation

simulation, proton, collider, emittance

9

D. Xu, C. Montag
BNL, Upton, New York, USA
Y. Hao
FRIB, East Lansing, Michigan, USA
Y. Luo
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
J. Qiang
LBNL, Berkeley, California, USA

The ion beam is sensitive to numerical noise in the strong-strong simulation of the Electron-Ion Collider (EIC). This paper discusses the impact of model parameters — macro particles, transverse grids and longitudinal slices — on beam size evolution in PIC based strong-strong simulation. It will help us to understand the emittance growth in strong-strong simulation.

Slides MOYD4 [0.849 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYD4

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Received ※ 02 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 11 August 2022

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MOYD5

Tolerances of Crab Dispersion at the Interaction Point in the Hadron Storage Ring of the Electron-Ion Collider

proton, simulation, dynamic-aperture, cavity

12

Y. Luo, J.S. Berg, M. Blaskiewicz, C. Montag, V. Ptitsyn, F.J. Willeke, D. Xu
BNL, Upton, New York, USA
Y. Hao
FRIB, East Lansing, Michigan, USA
V.S. Morozov
ORNL RAD, Oak Ridge, Tennessee, USA
J. Qiang
LBNL, Berkeley, California, USA
T. Satogata
JLab, Newport News, Virginia, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The Electron Ion Collider (EIC) presently under construction at Brookhaven National Laboratory will collide polarized high energy electron beams with hadron beams with luminosity up to 10³⁴ cm^-2 s^-1 in the center mass energy range of 20 to 140 GeV. Due to the detector solenoid in the interaction region, the design horizontal crabbing angle will be coupled to the vertical plane if uncompensated. In this article, we estimate the tolerance of crab dispersion at the interaction point in the EIC Hadron Storage Ring (HSR). Both strong-strong and weak-strong simulations are used. We found that there is a tight tolerance of vertical crabbing angle at the interaction point in the HSR.

Slides MOYD5 [1.183 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYD5

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Received ※ 01 August 2022 — Accepted ※ 04 August 2022 — Issue date ※ 15 August 2022

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MOYE6

Spin-Polarized Electron Photoemission and Detection Studies

experiment, simulation, cathode, polarization

26

A.C. Rodriguez Alicea, R. Palai
University of Puerto Rico, Rio Piedras Campus, San Juan, Puerto Rico
O. Chubenko, S.S. Karkare
Arizona State University, Tempe, USA
L. Cultrera
BNL, Upton, New York, USA

Funding: Brookhaven National Laboratory and the Department of Energy of United States under contract No. DE-SC0012704 Also, the Center for Bright Beams, NSF award PHY-1549132.
The experimental investigation of new photocathode ma- terials is time-consuming, expensive, and difficult to accom- plish. Computational modelling offers fast and inexpensive ways to explore new materials, and operating conditions, that could potentially enhance the efficiency of polarized electron beam photocathodes. We report on Monte-Carlo simulation of electron spin polarization (ESP) and quantum efficiency (QE) of bulk GaAs at 2, 77, and 300 K using the data obtained from Density Functional Theory (DFT) cal- culations at the corresponding temperatures. The simulated results of ESP and QE were compared with reported exper- imental measurements, and showed good agreement at 77 and 300 K.

Slides MOYE6 [6.235 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYE6

About •

Received ※ 03 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 04 September 2022

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MOZD2

Preliminary Study of a High Gain THz FEL in a Recirculating Cavity

radiation, undulator, FEL, GUI

30

A.C. Fisher, P. Musumeci
UCLA, Los Angeles, California, USA

The THz gap is a region of the electromagnetic spectrum where high average and peak power radiation sources are scarce while at the same time scientific and industrial applications are growing in demand. Free-electron laser coupling in a magnetic undulator is one of the best options for radiation generation in this frequency range, but slippage effects require the use of relatively long and low current electron bunches to drive the THz FEL, limiting amplification gain and output peak power. Here we use a circular waveguide in a 0.96 m strongly tapered helical undulator to match the radiation and e-beam velocities, allowing resonant energy extraction from an ultrashort 200 pC 5.5 MeV electron beam over an extended distance. E-beam energy measurements, supported by energy and spectral measurement of the THz FEL radiation, indicate an average energy efficiency of ~ 10%, with some particles losing > 20% of their initial kinetic energy.

Slides MOZD2 [7.005 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZD2

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Received ※ 04 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 13 August 2022

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MOZD4

Uncertainty Quantification of Beam Parameters in a Linear Induction Accelerator Inferred from Bayesian Analysis of Solenoid Scans

solenoid, experiment, induction, space-charge

34

M.A. Jaworski, D.C. Moir, S. Szustkowski
LANL, Los Alamos, New Mexico, USA

Linear induction accelerators (LIAs) such as the DARHT at Los Alamos National Laboratory make use of the beam envelope equation to simulate the beam and design experiments. Accepted practice is to infer beam parameters using the solenoid scan technique with optical transition radiation (OTR) beam profiles. These scans are then analyzed with an envelope equation solver to find a solution consistent with the data and machine parameters (beam energy, current, magnetic field, and geometry). The most common code for this purpose with flash-radiography LIAs is xtr [1]. The code assumes the machine parameters are perfectly known and that beam profiles will follow a normal distribution about the best fit and solves by minimizing a chi-square-like metric. We construct a Bayesian model of the beam parameters allowing maching parameters, such as solenoid position, to vary within reasonable uncertainty bounds. Posterior distribution functions are constructed using Markov-Chain Monte Carlo (MCMC) methods to evaluate the accuracy of the xtr solution uncertainties and the impact of finite precision in measurements.
[1] P.W. Allison, "Beam dynamics equations for xtr," Los Alamos Technical Report LA-UR-01-6585. November 2001.

Slides MOZD4 [1.082 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZD4

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Received ※ 05 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 20 August 2022

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MOZD5

ERL-Based Compact X-Ray FEL

FEL, emittance, optics, laser

37

F. Lin, V.S. Morozov
ORNL RAD, Oak Ridge, Tennessee, USA
J. Guo, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: Work supported by UT-Battelle, LLC, under contract DE-AC05-00OR22725, and by Jefferson Science Associates, LLC, under contract DE-AC05-06OR23177
We propose to develop an energy-recovery-linac (ERL)-based X-ray free-electron laser (XFEL). Taking advantage of the demonstrated high-efficiency energy recovery of the beam power in the ERL, the proposed concept offers the following benefits: i) recirculating the electron beam through high-gradient superconducting RF (SRF) cavities shortens the linac, ii) energy recovery in the SRF linac saves the klystron power and reduces the beam dump power, iii) the high average beam power produces a high average photon brightness. In addition, such a concept has the capability of delivering optimized high-brightness CW X-ray FEL performance at different energies with simultaneous multipole sources. In this paper, we will present the preliminary results on the study of feasibility, optics design and parameter optimization of such a device.

Slides MOZD5 [2.870 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZD5

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Received ※ 02 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 04 August 2022 — Issue date ※ 11 September 2022

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MOZD6

Accelerator Physics Lessons from CBETA, the First Multi-Turn SRF ERL

linac, SRF, cavity, photon

41

K.E. Deitrick
JLab, Newport News, Virginia, USA
G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The Cornell-BNL ERL Test Accelerator (CBETA) has been designed, constructed, and commissioned in a collaboration between Cornell and BNL. It focuses on energy-saving measures in accelerators, including permanent magnets, energy recovery, and superconductors; it has thus been referred to as a green accelerator. CBETA has become the world’s first Energy Recovery Linac (ERL) that accelerates through multiple turns and then recovers the energy in SRF cavities though multiple decelerating turns. The energy is then available to accelerate more beam. It has also become the first accelerator that operates 7 beams in the same large-energy aperture Fixed Field Alternating-gradient (FFA) lattice. The FFA is constructed of permanent combined function magnets and transports energies of 42, 78, 114, and 150 MeV simultaneously. Accelerator physics lessons from the commissioning period will be described and applications of such an accelerator from hadron cooling to EUV lithography and from nuclear physics to a compact Compton source will be discussed.

Slides MOZD6 [3.207 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZD6

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Received ※ 23 July 2022 — Revised ※ 27 July 2022 — Accepted ※ 03 August 2022 — Issue date ※ 06 August 2022

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MOZE4

Ceramic Enhanced Accelerator Structure Low Power Test and Designs of High Power and Beam Tests

cavity, impedance, accelerating-gradient, simulation

49

H. Xu, M.R. Bradley, L.D. Duffy, M.A. Holloway, J. Upadhyay
LANL, Los Alamos, New Mexico, USA

Funding: Research was supported by the Laboratory Directed Research and Development program of Los Alamos National Laboratory, under project number 20210083ER.
A ceramic enhanced accelerator structure (CEAS) uses a concentric ceramic ring placed inside a metallic pillbox cavity to significantly increase the shunt impedance of the cavity. Single cell standing wave CEAS cavities are designed, built, and tested at low power at 5.1 GHz. The results indicate 40% increase in shunt impedance compared to that of a purely metallic pillbox cavity. A beam test setup has been designed to use a single cell CEAS cavity to modulate a 30-keV direct-current (DC) electron beam at an accelerating gradient of 1 to 2 MV/m to verify the beam acceleration capability of the CEAS concept and to study the potential charging effect on the ceramic component during the operation. Another single cell standing wave CEAS cavity has been designed for high power test at 5.7 GHz for the high accelerating gradient capability.

Slides MOZE4 [1.652 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZE4

About •

Received ※ 01 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 07 October 2022

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MOPA13

Design of a Surrogate Model for MUED at BNL Using VSim, Elegant and HPC

simulation, gun, detector, laser

72

S.I. Sosa Guitron, S. Biedron, T.B. Bolin
UNM-ECE, Albuquerque, USA
S. Biedron
Element Aero, Chicago, USA
S. Biedron
UNM-ME, Albuquerque, New Mexico, USA

Funding: U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Program of Electron and Scanning Probe Microscopes, award number DE-SC0021365.
The MeV Ultrafast Electron Diffraction (MUED) instrument at Brookhaven National Laboratory is a unique capability for material science. As part of a plan to make MUED a high-throughput user facility, we are exploring instrumentation developments based on Machine Learning (ML). We are developing a surrogate model of MUED that can be used to support control tasks. The surrogate model will be based on beam simulations that are benchmarked to experimental observations. We use VSim to model the beam dynamics of the radio-frequency gun and Elegant to transport the beam through the rest of the beam-line. We also use High Performance Computing resources from Argonne Leadership Computing Facility to generate the data for the surrogate model based on the original simulation as well as training the ML model.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA13

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Received ※ 01 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 21 August 2022

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MOPA17

Symplectic Particle Tracking in a Thick Nonlinear McMillan Lens for the Fermilab Integrable Optics Test Accelerator (IOTA)

solenoid, optics, simulation, lattice

83

B.L. Cathey, G. Stancari, T. Zolkin
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The McMillan system is a novel method to increase the tune spread of a beam without decreasing its dynamic aperture due to the system’s integrability. While the ideal system is based on an infinitely thin kick, the physical design requires a thick electron lens, including a solenoid. Particle transport through the lens is difficult to simulate due to the nature of the force on the circulating beam. This paper demonstrates accurate simulation of a thick McMillan lens in a solenoid using symplectic integrators derived from Yoshida’s method.

Poster MOPA17 [2.290 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA17

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Received ※ 03 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 09 October 2022

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MOPA30

LCLS-II BCS Average Current Monitor

cavity, hardware, MMI, LLRF

120

N.M. Ludlow, T.L. Allison, J.P. Sikora, J.J. Welch
SLAC, Menlo Park, California, USA

LCLS-II is a 4th generation light source at the SLAC National Accelerator Laboratory. LCLS-II will accelerate a 30 µA electron beam with a 1 MHz bunch rate with a new superconducting Continuous Waveform (CW) RF accelerator. The Average Current Monitor (ACM) is part of the Beam Containment System (BCS) for the LCLS-II accelerator. The Beam Containment System is a safety system that provides paths to safely shut the accelerator beam off under a variety of conditions. The Average Current Monitor is a beam diagnostic within the BCS that is used to verify that the accelerator is producing the appropriate current level and to limit beam power to allowed values to protect the machine and beam dumps. The average beam current is obtained by measuring the power level induced by the beam in a low Q cavity. By knowing the Q, the beta, and the coupling of the cavity, the instantaneous charge can be calculated, then integrating the instantaneous charge over one millisecond will yield the average current. This paper will discuss progress in the checkout process of the ACM LLRF hardware leading to LCLS-II commissioning.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA30

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Received ※ 16 July 2022 — Revised ※ 05 August 2022 — Accepted ※ 24 August 2022 — Issue date ※ 06 October 2022

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MOPA34

Noise in Intense Electron Bunches

laser, radiation, FEL, experiment

128

S. Nagaitsev, D.R. Broemmelsiek, J.D. Jarvis, A.H. Lumpkin, J. Ruan, G.W. Saewert, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA
Z. Huang, G. Stupakov
SLAC, Menlo Park, California, USA
Y.K. Kim
University of Chicago, Chicago, Illinois, USA

We report on our investigations into density fluctuations in electron bunches. Noise and density fluctuations in relativistic electron bunches, accelerated in a linac, are of critical importance to various Coherent Electron Cooling (CEC) concepts as well as to free-electron lasers (FELs). For CEC, the beam noise results in additional diffusion that counteracts cooling. In SASE FELs, a microwave instability starts from the initial noise in the beam and eventually leads to the beam microbunching yielding coherent radiation, and the initial noise in the FEL bandwidth plays a useful role. In seeded FELs, in contrast, such noise interferes with the seed signal, so that reducing noise at the initial seed wavelength would lower the seed laser power requirement. Status of the project will be presented.

Poster MOPA34 [0.638 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA34

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Received ※ 10 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 14 August 2022 — Issue date ※ 24 August 2022

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MOPA45

Vacuum Electron Devices in the 88-Inch Cyclotron

cyclotron, ECR, radiation, plasma

154

M. Kireeff Covo, J.Y. Benitez, P. Bloemhard, J.P. Garcia, B. Ninemire, L. Phair, D.S. Todd, D.Z. Xie
LBNL, Berkeley, California, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract No. DE-AC02-05CH11231
The 88-Inch Cyclotron at Lawrence Berkeley National Laboratory is a sector-focused cyclotron that has light- and heavy-ion capabilities and supports a local research program in Nuclear Science and is the home of the Berkeley Accelerator Space Effects Facility, which studies effects of radiation on microelectronics, optics, materials, and cells. The cyclotron utilizes several vacuum electron devices (VEDs) in different systems, mainly to convey plasma heating, high power RF generation, and high-voltage and current DC power generation. VEDs have been proven reliable, robust, and radiation resistant. They also have wide range, good response against transients, and stable operation with load mismatch during system tuning, instabilities, or breakdowns. The paper will describe applications of these devices in the 88-Inch Cyclotron

Poster MOPA45 [1.434 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA45

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Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 12 September 2022

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MOPA59

Prediction of Gaseous Breakdown for Plasma Cleaning of RF Cavities

simulation, cavity, plasma, electronics

174

S.A. Ahmed
Ansys, Inc., Canonsburg, USA

The quest for a high accelerating gradient in superconducting radio frequency cavity attracted scientists to adopt the plasma cleaning technology. Generating an efficient plasma inside a complex cavity structure for a desired frequency, gas types, and pressure for a given temperature is a challenge. The onset of discharge can be obtained from the well-known Paschen curve. Setting up an experiment is expensive and time-consuming, which may lead to a significant delay in the project. A high-fidelity computer simulation, modeling an arbitrary geometry and tracking the Paschen curve in a complex electromagnetic environment is therefore necessary. Ansys HFSS through its Finite Element Mesh (FEM) for the full-wave EM simulations combined with the electron impact ionization of gases enables the successful prediction of plasma breakdown for an arbitrary configuration for a wide frequency band and variety of gases. A comprehensive study will be demonstrated at the conference.
The author like to thank Robert Chao for the valuable discussions and his efforts in developing this capability in the Ansys Electronics Desktop.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA59

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Received ※ 01 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 19 August 2022

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MOPA60

HFSS Enables Multipaction Analysis of High Power RF/Microwave Components

multipactoring, simulation, cavity, vacuum

176

S.A. Ahmed
Ansys, Inc., Canonsburg, USA

The radiofrequency (RF) components in particle accelerators operated under a vacuum and driven by high RF power may be prone to electron multipaction ’ an RF triggered electron resonance phenomenon causing malfunction or complete breakdown. Therefore, exploring the design challenges of vacuum RF windows, cavities, and other devices for the electron multipaction becomes necessary. Setting up an experiment to mitigate the failure of RF devices is expensive and time-consuming, which may cause a significant delay in the project. Therefore, a high-fidelity computer simulation modeling the arbitrary geometry and tracking the particles (electrons) in a complex electromagnetic environment is desirable. Ansys HFSS through Finite Element Mesh (FEM) for the full-wave RF simulation combined with the particle-in-cell (PIC) technique for tracking particles in EM fields; enables the engineers/physicist successful prediction of system failure against the electron multipaction. This paper will demonstrate the workflow of the HFSS multipaction analysis.
The author like to thank Robert Chao for the valuable discussions and his efforts in developing this capability in the Ansys Electronics Desktop.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA60

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Received ※ 03 August 2022 — Revised ※ 13 August 2022 — Accepted ※ 26 August 2022 — Issue date ※ 06 October 2022

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MOPA69

Adjoint Optimization Applied to Flat to Round Transformers

solenoid, quadrupole, lattice, space-charge

199

T.M. Antonsen, B.L. Beaudoin, S. Bernal, L. Dovlatyan, I. Haber, P.G. O’Shea, D.F. Sutter
UMD, College Park, Maryland, USA

Funding: This work was supported by DOE-HEP Awards No. DESC0010301 and DESC0022009
We present the numerical optimization, using adjoint techniques, of Flat-to-Round (FTR) transformers operating in the strong self-field limit. FTRs transform an unmagnetized beam that has a high aspect ratio, elliptical spatial cross section, to a round beam in a solenoidal magnetic field. In its simplest form the flat to round conversion is accomplished with a triplet of quadrupoles, and a solenoid. FTR transformers have multiple applications in beam physics research, including manipulating electron beams to cool co-propagating hadron beams. Parameters that can be varied to optimize the FTR conversion are the positions and strengths of the four magnet elements, including the orientations and axial profiles of the quadrupoles and the axial profile and strength of the solenoid’s magnetic field. The adjoint method we employ [1] allows for optimization of the lattice with a minimum computational effort including self-fields. The present model is based on a moment description of the beam. However, the generalization to a particle description will be presented. The optimized designs presented here will be tested in experiments under construction at the University of Maryland.
[1] Optimization of Flat to Round Transformers with self-fields using adjoint techniques, L. Dovlatyan, B. Beaudoin, S. Bernal, I. Haber, D. Sutter and TMA, PhysRevAccelBeams.25.044002 (2022).

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA69

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Received ※ 03 August 2022 — Revised ※ 25 September 2022 — Accepted ※ 05 December 2022 — Issue date ※ 05 December 2022

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MOPA70

Film Dosimetry Characterization of the Research Linac at the University of Maryland

linac, radiation, vacuum, experiment

203

A.S. Johnson, L.T. Gilde, M.K. Hottinger, T.W. Koeth
UMD, College Park, Maryland, USA

A heavily modified Varian linac was installed as part of the University of Maryland Radiation Facilities in the early 1980s. The electron linac was initially used for materials testing and pulsed radiolysis. Overtime, diagnostics such as a spectrometer magnet and scintillator screens have been removed, limiting the ability to describe the electron beam. The beamline is currently configured with a thin titanium window to allow the electrons to escape the vacuum region and interact with samples in air. A calibrated film dosimetry system was used to characterize the transverse beam dimensions and uniformity in air. The results of these experimental measurements will be described in this paper.

Poster MOPA70 [3.423 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA70

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Received ※ 27 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 20 August 2022

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MOPA72

Preliminary Tests and Beam Dynamics Simulations of a Straight-Merger Beamline

dipole, experiment, simulation, cavity

206

A.A. Al Marzouk, P. Piot, T. Xu
Northern Illinois University, DeKalb, Illinois, USA
S.V. Benson, K.E. Deitrick, J. Guo, A. Hutton, G.-T. Park, S. Wang
JLab, Newport News, Virginia, USA
D.S. Doran, G. Ha, P. Piot, J.G. Power, C. Whiteford, E.E. Wisniewski
ANL, Lemont, Illinois, USA
C.E. Mitchell, J. Qiang, R.D. Ryne
LBNL, Berkeley, California, USA

Funding: NSF award PHY-1549132 to Cornell University and NIU, U.S. DOE contract DE-AC02-06CH11357 with ANL and DE-AC05-06OR23177 with JLAB.
Beamlines capable of merging beams with different energies are critical to many applications related to advanced accelerator concepts and energy-recovery linacs (ERLs). In an ERL, a low-energy "fresh" bright bunch is generally injected into a superconducting linac for acceleration using the fields established by a decelerated "spent" beam traveling on the same axis. A straight-merger system composed of a selecting cavity with a superimposed dipole magnet was proposed and recently test at AWA. This paper reports on the experimental results obtained so far along with detailed beam dynamics investigations of the merger concept and its ability to conserve the beam brightness associated with the fresh bunch.

Poster MOPA72 [1.659 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA72

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Received ※ 11 August 2022 — Accepted ※ 13 August 2022 — Issue date ※ 02 October 2022

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MOPA74

Design of a W-Band Corrugated Waveguide for Structure Wakefield Acceleration

wakefield, GUI, acceleration, accelerating-gradient

210

B. Leung, X. Lu, C.L. Phillips, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
D.S. Doran, X. Lu, P. Piot, J.G. Power
ANL, Lemont, Illinois, USA

Current research on structure wakefield acceleration aims to develop radio-frequency structures that can produce high gradients, with work in the sub-terahertz regime being particularly interesting because of the potential to create more compact and economical accelerators. Metallic corrugated waveguides at sub-terahertz frequencies are one such structure. We have designed a W-band corrugated waveguide for a collinear wakefield acceleration experiment at the Argonne Wakefield Accelerator (AWA). Using the CST Studio Suite, we have optimized the structure for the maximum achievable gradient in the wakefield from a nominal AWA electron bunch at 65 MeV. Simulation results from different solvers of CST were benchmarked with each other, with analytical models, and with another simulation code, ECHO. We are investigating the mechanical design, suitable fabrication technologies, and the possibility to apply advanced bunch shaping techniques to improve the structure performance.

Poster MOPA74 [1.518 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA74

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Received ※ 30 July 2022 — Revised ※ 03 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 26 August 2022

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MOPA76

Wakefield Modeling in Sub-THz Dielectric-Lined Waveguides

wakefield, simulation, GUI, experiment

218

C.L. Phillips, B. Leung, X. Lu, P. Piot
Northern Illinois University, DeKalb, Illinois, USA

Dielectric-lined waveguides have been extensively studied to potentially support high-gradient acceleration in beam-driven dielectric wakefield acceleration (DWFA) and for beam manipulations. In this paper, we investigate the wakefield generated by a relativistic bunch passing through a dielectric waveguide with different transverse sections. We specifically consider the case of a structure consisting of two dielectric slabs, along with rectangular and square structures. Numerical simulations performed with the fine-difference time-domain of the WarpX program reveal some interesting features of the transverse wake and a possible experiment at the Argonne Wakefield Accelerator (AWA) is proposed.

Poster MOPA76 [1.294 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA76

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Received ※ 12 August 2022 — Accepted ※ 13 August 2022 — Issue date ※ 12 September 2022

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MOPA78

Temporally-Shaped Ultraviolet Pulses for Tailored Bunch Generation at Argonne Wakefield Accelerator

laser, controls, wakefield, cathode

222

T. Xu, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
S. Carbajo
UCLA, Los Angeles, California, USA
S. Carbajo, R.A. Lemons
SLAC, Menlo Park, California, USA
P. Piot
ANL, Lemont, Illinois, USA

Photocathode laser shaping is an appealing technique to generate tailored electron bunches due to its versatility and simplicity. Most photocathodes require photon energies exceeding the nominal photon energy produced by the lasing medium. A common setup consists of an infrared (IR) laser system with nonlinear frequency conversion to the ultraviolet (UV). In this work, we present the numerical modeling of a temporal shaping technique capable of producing electron bunches with linearly-ramped current profiles for application to collinear wakefield accelerators. Specifically, we show that controlling higher-order dispersion terms associated with the IR pulse provides some control over the UV temporal shape. Beam dynamics simulation of an electron-bunch shaping experiment at the Argonne Wakefield Accelerator is presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA78

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Received ※ 01 August 2022 — Revised ※ 06 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 31 August 2022

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MOPA80

Design Study for Non-Intercepting Gas-Sheet Profile Monitor at FRIB

photon, heavy-ion, detector, simulation

229

A. Lokey, S.M. Lidia
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the US Department of Energy, Office of Science, High Energy Physics under Cooperative Agreement award number DE-SC0018362 and Michigan State University.
Non-invasive profile monitors offer a significant advantage for continuous, online monitoring of transverse beam profile and tuning of beam parameters during operation. This is due to both the non-destructive nature of the measurement and the unique feature that some monitors have of being able to determine both transverse profiles in one measurement [1]. One method of interest for making this measurement is the use of a thin gas curtain, which intercepts the beam and generates both ions and photons, which can be collected at a detector situated perpendicular to the gas sheet. This study will investigate the requirements for developing such a measurement device for use at the Facility for Rare Isotope Beams (FRIB), which produces high-intensity, multi charge state, heavy ion beams. Included will be an initial design specifications and an analysis of alternatives between ionization and beam-induced fluorescence measurement techniques for acquiring signal from the gas sheet.
[1] I. Yamada, M. Wada, K. Moriya, et al, "High-intensity beam profile measurement using a gas sheet monitor by beam induced fluorescence detection," Phys. Rev. Accel. Beams 24, 042801, 2021.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA80

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Received ※ 03 August 2022 — Revised ※ 06 August 2022 — Accepted ※ 06 September 2022 — Issue date ※ 07 October 2022

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MOPA85

Design of a 185.7 MHz Superconducting RF Photoinjector Quarter-Wave Resonator for the LCLS-II-HE Low Emittance Injector

cavity, SRF, gun, cathode

245

S.H. Kim, W. Hartung, T. Konomi, S.J. Miller, M.S. Patil, J.T. Popielarski, K. Saito, T. Xu, T. Xu
FRIB, East Lansing, Michigan, USA
C. Adolphsen, L. Ge, F. Ji, J.W. Lewellen, L. Xiao
SLAC, Menlo Park, California, USA
M.P. Kelly, T.B. Petersen, P. Piot
ANL, Lemont, Illinois, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA

Funding: Work supported by the U.S. Department of Energy Contract DE-AC02-76SF00515.
A 185.7 MHz superconducting quarter-wave resonator (QWR) was designed for the low emittance injector of the Linac Coherent Light Source high energy upgrade (LCLS-II-HE). The cavity was designed to minimize the risk of cathode efficiency degradation due to multipacting or field emission and to operate with a high RF electric field at the cathode for low electron-beam emittance. Cavity design features include: (1) shaping of the cavity wall to reduce the strength of the low-field coaxial multipacting barrier; (2) four ports for electropolishing and high-pressure water rinsing; and (3) a fundamental power coupler (FPC) port located away from the accelerating gap. The design is oriented toward minimizing the risk of particulate contamination and avoid harmful dipole components in the RF field. The ANL 162 MHz FPC design for PIP-II is being adapted for the gun cavity. We will present the RF design of the cavity integrated with the FPC.

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA85

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Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 30 August 2022

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MOPA86

Conditioning of Low-Field Multipacting Barriers in Superconducting Quarter-Wave Resonators

cavity, coupling, multipactoring, cryomodule

249

S.H. Kim, W. Chang, W. Hartung, J.T. Popielarski, T. Xu
FRIB, East Lansing, Michigan, USA

Funding: This is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University.
Multipacting (MP) barriers are typically observed at very low RF amplitude, at a field 2 to 3 orders of magnitude below the operating gradient, in low-frequency (<~100 MHz), quarter-wave resonators (QWRs). Such barriers may be troublesome, as RF conditioning with a fundamental power coupler (FPC) of typical coupling strength (external Q = 10⁶ to 10⁷) is generally difficult. For the FRIB \beta = 0.085 QWRs (80.5 MHz), the low barrier is observed at an accelerating gradient (E_acc) of ~10 kV/m; the operating E_acc is 5.6 MV/m. Theoretical and simulation studies suggested that the conditioning is difficult due to the relatively low RF power dissipated into multipacting rather than being a problem of the low barrier being stronger than other barriers. We developed a single-stub coaxial FPC matching element for external adjustment of the external Q by one order of magnitude. The matching element provided a significant reduction in the time to condition the low barrier. We will present theoretical and simulation studies of the low MP barrier and experimental results on MP conditioning with the single-stub FPC matching element.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA86

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Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 21 August 2022

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MOPA89

RHIC Electron Beam Cooling Analysis Using Principle Component and Autoencoder Analysis

luminosity, ECR, network, beam-cooling

260

A.D. Tran, Y. Hao
FRIB, East Lansing, Michigan, USA
X. Gu
BNL, Upton, New York, USA

Funding: Work supported by the US Department of Energy under contract No. DE-AC02-98CH10886.
Principal component analysis and autoencoder analysis were used to analyze the experimental data of RHIC operation with low energy RHIC electron cooling (LEReC). This is unsupervised learning which includes electron beam settings and observable during operation. Both analyses were used to gauge the dimensional reducibility of the data and to understand which features are important to beam cooling.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA89

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Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 12 August 2022

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TUXD4

Analysis Methods for Electron Radiography Based on Laser-Plasma Accelerators

laser, plasma, target, experiment

274

G.M. Bruhaug, G.W. Collins, H.G. Rinderknecht, J.R. Rygg, J.L. Shaw, M.S. Wei
LLE, Rochester, New York, USA
M.S. Freeman, F.E. Merrill, L.P. Neukirch, C. Wilde
LANL, Los Alamos, New Mexico, USA

Funding: DOE National Nuclear Security Administration under Award Number DE-NA0003856 DOE under Awards DE-SC00215057 University of Rochester New York State Energy Research and Development Authority
Analysis methods are presented for determining the res-olution of both contact and projected electron radiography based on a laser-plasma accelerator. A means to determine the field strength of the electric/magnetic fields generated when a laser is incident on an object of interest is also outlined. Broad radiography results are reported and future plans for the diagnostic technique are outlined.

Slides TUXD4 [12.157 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUXD4

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Received ※ 02 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 03 September 2022

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TUXD6

Dual Radiofrequency Cavity Based Monochromatization for High Resolution Electron Energy Loss Spectroscopy

cavity, cathode, simulation, space-charge

278

A.V. Kulkarni, P.E. Denham, A. Kogar, P. Musumeci
UCLA, Los Angeles, USA

Reducing the energy spread of electron beams can enable breakthrough advances in electron energy loss spectroscopic investigations of solid state samples where characteristic excitations typically have energy scales on the order of meV. In conventional electron sources the energy spread is limited by the emission process and typically on the order of a fraction of an eV. State-of-the-art energy resolution can only be achieved after significant losses in the monochromatization process. Here we propose to take advantage of photoemission from ultrashort laser pulses (~40 fs) so that after a longitudinal phase space manipulation that trades pulse duration for energy spread, the energy spread can be reduced by more than one order of magnitude. The scheme uses two RF cavities to accomplish this goal and can be implemented on a relatively short (~ 1m) beamline. Analytical predictions and results of 3D self consistent beam dynamics simulations are presented to support the findings.

Slides TUXD6 [1.461 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUXD6

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Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 18 August 2022

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TUYD3

The Quest for the Perfect Cathode

cathode, gun, emittance, photon

281

J.W. Lewellen, J. Smedley, T. Vecchione
SLAC, Menlo Park, California, USA
D. Filippetto
LBNL, Berkeley, California, USA
S.S. Karkare
Arizona State University, Tempe, USA
J.M. Maxson
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
P. Musumeci
UCLA, Los Angeles, California, USA

Funding: U.S. Department of Energy.
The next generation of free electron lasers will be the first to see the performance of the laser strongly dependent on the materials properties of the photocathode. A new injector proposed for the LCLS-II HE is an example of this revolution, with the goal of increasing the photon energy achievable by LCLS-II to over 20 keV. We must now ask, what is the optimal cathode, temperature, and laser combination to enable this injector? There are many competing requirements. The cathode must be robust enough to operate in a superconducting injector, and must not cause contamination of the injector. It must achieve sufficient charge at high repetition rate, while minimizing the emittance. The wavelength chosen must minimize mean transverse energy while maintaining tolerable levels of multi-photon emission. The cathode must be capable of operating at high (~30 MV/m) gradient, which puts limits on both surface roughness and field emission. This presentation will discuss the trade space for such a cathode/laser combination, and detail a new collaborative program among a variety of institutions to investigate it.

Slides TUYD3 [1.632 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYD3

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Received ※ 02 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 14 August 2022 — Issue date ※ 26 September 2022

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TUYD4

Towards High Brightness from Plasmon-Enhanced Photoemitters

cathode, laser, interface, emittance

285

C.M. Pierce, I.V. Bazarov, J.M. Maxson
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
D.B. Durham, D. Filippetto, F. Riminucci
LBNL, Berkeley, USA
A.H. Kachwala, S.S. Karkare
Arizona State University, Tempe, USA
A. Minor
UC Berkeley, Berkeley, California, USA

Funding: This work is supported by DOE BES Contract No. DE-AC02-05CH11231. C.P. acknowledges NSF Award PHY-1549132 (CBB) and the US DOE SCGSR program. DD was supported by NSF Grant No. DMR-1548924 (STROBE).
Plasmonic cathodes, whose nanoscale features may locally enhance optical energy from the driving laser trapped at the vacuum interface, have emerged as a promising technology for improving the brightness of metal cathodes. A six orders of magnitude improvement [1] in the non-linear yield of metals has been experimentally demonstrated through this type of nanopatterning. Further, nanoscale lens structures may focus light below its free-space wavelength offering multiphoton photoemission from a region near 10 times smaller [2] than that achievable in typical photoinjectors. In this proceeding, we report on our efforts to characterize the brightness of two plasmonic cathode concepts: a spiral lens and a nanogroove array. We demonstrate an ability to engineer and fabricate nanoscale patterned cathodes by comparing their optical properties with those computed with a finite difference time domain (FDTD) code. The emittance and nonlinear yield of the cathodes are measured under ultrafast laser irradiation. Finally, prospects of this technology for the control and acceleration of charged particle beams are discussed.
[1] Polyakov, A., et al. (2013). Physical Review Letters, 110(7), 076802.
[2] Durham, D. B., et al. (2019). Physical Review Applied, 12(5), 054057.

Slides TUYD4 [7.160 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYD4

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Received ※ 05 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 13 September 2022

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TUYD5

Epitaxial Alkali-Antimonide Photocathodes on Lattice-matched Substrates

cathode, ECR, laser, lattice

289

P. Saha, S.S. Karkare
Arizona State University, Tempe, USA
E. Echeverria, A. Galdi, J.M. Maxson, C.A. Pennington
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
E.J. Montgomery, S. Poddar
Euclid Beamlabs, Bolingbrook, USA

Alkali-antimonides photocathodes, characterized by high quantum efficiency (QE) and low mean transverse energy (MTE) in the visible range of spectrum, are excellent candidates for electron sources to drive X-ray Free Electron Lasers (XFEL) and Ultrafast Electron Diffraction (UED). A key figure of merit for these applications is the electron beam brightness, which is inversely proportional to MTE. MTE can be limited by nanoscale surface roughness. Recently, we have demonstrated physically and chemically smooth Cs₃Sb cathodes on Strontium Titanate (STO) substrates grown via co-deposition technique. Such flat cathodes could result from a more ordered growth. In this paper, we present RHEED data of co-deposited Cs₃Sb cathodes on STO. Efforts to achieve epitaxial growth of Cs₃Sb on STO are then demonstrated via RHEED. We find that films grown epitaxially on substrates like STO and SiC (previously used to achieve single crystalline Cs₃Sb) exhibit QE higher than the polycrystalline Cs₃Sb cathodes, by an order of magnitude below photoemission threshold. Given the larger QE, lower laser fluence could be used to extract high charge densities, thereby leading to enhanced beam brightness.

Slides TUYD5 [2.088 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYD5

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Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 07 September 2022

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TUYD6

Design of a 200 kV DC Cryocooled Photoemission Gun for Photocathode Investigations

cathode, gun, MMI, cryogenics

292

G.S. Gevorkyan, T.J. Hanks, A.H. Kachwala, S.S. Karkare, C.J. Knill, C.A. Sarabia Cardenas
Arizona State University, Tempe, USA

Funding: This work was supported by the U.S. National Science Foundation under Award No. PHY-1549132, the Center for Bright Beams, and the DOE under Grant No. DE-SC0021092.
We present the first results of the commissioning of the 200 kV DC electron gun with a cryogenically cooled cathode at Arizona State University. The gun is specifically designed for studying a wide variety of novel cathode materials including single crystalline and epitaxially grown materials at 30 K temperatures to obtain the lowest possible intrinsic emittance of UED and XFEL applications [1]. We will present the measurements of the cryogenic performance of the gun and the first high voltage commissioning results.
[1] G. S. Gevorkyan et. al., Proc. of NAPAC19 MOPLM16 (2019)

Slides TUYD6 [12.632 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYD6

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Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 29 September 2022

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TUZD1

The Electron-Positron Future Circular Collider (FCC-ee)

collider, operation, luminosity, booster

315

F. Zimmermann, M. Benedikt
CERN, Meyrin, Switzerland
K. Oide
DPNC, Genève, Switzerland
T.O. Raubenheimer
SLAC, Menlo Park, California, USA

Funding: Work supported by the European Union’s H2020 Framework Programme under grant agreement no.~951754 (FCCIS).
The Future Circular electron-positron Collider (FCC-ee) is aimed at studying the Z and W bosons, the Higgs, and top quark with extremely high luminosity and good energy efficiency. Responding to a request from the 2020 Update of the European Strategy for Particle Physics, in 2021 the CERN Council has launched the FCC Feasibility Study to examine the detailed implementation of such a collider. This FCC Feasibility Study will be completed by the end of 2025 and its results be presented to the next Update of the European Strategy for Particle Physics expected in 2026/27.

Slides TUZD1 [10.072 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZD1

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Received ※ 03 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 21 August 2022 — Issue date ※ 02 September 2022

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TUZD3

Ultimate Limits of Future Colliders

collider, luminosity, acceleration, factory

321

M. Bai
SLAC, Menlo Park, California, USA
V.D. Shiltsev
Fermilab, Batavia, Illinois, USA
F. Zimmermann
CERN, Meyrin, Switzerland

With seven operational colliders in the world and two under construction, the international particle physics community not only actively explores options for the next facilities for detailed studies of the Higgs/electroweak physics and beyond-the-LHC energy frontier, but seeks a clear picture of the limits of the colliding beams method. In this paper, we try to consolidate various recent efforts in identifying physics limits of colliders in conjunction with societal sustainability, and share our thoughts about the perspective of reaching the ultimate quantum limit.

Slides TUZD3 [3.848 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZD3

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Received ※ 25 July 2022 — Revised ※ 03 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 30 August 2022

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TUZD5

Experience and Challenges with Electron Cooling of Colliding Ion Beams in RHIC

operation, collider, cathode, emittance

325

A.V. Fedotov, X. Gu, D. Kayran, J. Kewisch, S. Seletskiy
BNL, Upton, New York, USA

Funding: Work supported by the U.S. Department of Energy.
Electron cooling of ion beams employing rf-accelerated electron bunches was successfully used for the RHIC physics program in 2020 and 2021 and was essential in achieving the required luminosity goals. This presentation will summarize experience and challenges with electron cooling of colliding ion beams in RHIC. We also outline ongoing studies using rf-based electron cooler LEReC.

Slides TUZD5 [1.373 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZD5

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Received ※ 02 August 2022 — Accepted ※ 04 August 2022 — Issue date ※ 14 September 2022

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TUZE1

Experimental Phase-Space Tracking of a Single Electron in a Storage Ring

betatron, photon, synchrotron, experiment

329

A.L. Romanov, J.K. Santucci, G. Stancari, A. Valishev
Fermilab, Batavia, Illinois, USA

This paper presents the results of the first ever experimental tracking of the betatron and synchrotron phases for a single electron in the Fermilab’s IOTA ring. The reported technology makes it is possible to fully track a single electron in a storage ring, which requires tracking of amplitudes and phases for both, slow synchrotron and fast betatron oscillations.

Slides TUZE1 [3.600 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZE1

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Received ※ 08 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 21 August 2022 — Issue date ※ 27 August 2022

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TUZE4

Particle-in-Cell Simulations of High Current Density Electron Beams in the Scorpius Linear Induction Accelerator

simulation, emittance, plasma, induction

339

S.E. Clark, Y.-J. Chen, J. Ellsworth, A.T. Fetterman, C.N. Melton, W.D. Stem
LLNL, Livermore, USA

Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Particle-in-cell (PIC) simulations of a high current density (I > 1 kA), and highly relativistic electron beam (E ~ 2-20 MeV) in the Scorpius Linear Induction Accelerator (LIA) are presented. The simulation set consists of a 3D electrostatic/magnetostatic simulation coupled to a 2D XY slice solver that propagates the beam through the proposed accelerator lattice for Scorpius, a next-generation flash X-ray radiography source. These simulations focus on the growth of azimuthal modes in the beam (e.g. Diocotron instability) that arise when physical ring distributions manifest in the beam either due to electron optics or solenoidal focusing and transport. The saturation mechanism appears to lead to the generation of halo particles and conversion down to lower mode numbers as the width of the ring distribution increases. The mode growth and saturation can contribute to the generation of hot spots on the target as well possible azimuthal asymmetries in the radiograph. Simulation results are compared to linear theory and tuning parameters are investigated to mitigate the growth of azimuthal modes in the Scorpius electron beam.
* LLNL-ABS-830595, Approved for public release. Distribution Unlimited.

Slides TUZE4 [4.305 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZE4

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Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 21 September 2022

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TUZE5

Studies of Ion Beam Heating by Electron Beams

emittance, experiment, gun, solenoid

343

S. Seletskiy, A.V. Fedotov, D. Kayran
BNL, Upton, New York, USA

Presence of an electron beam created by either electron coolers or electron lenses in an ion storage ring is associated with an unwanted emittance growth (heating) of the ion bunches. In this paper we report experimental studies of the electron-ion heating in the Low Energy RHIC electron Cooler (LEReC).

Slides TUZE5 [1.368 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZE5

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Received ※ 01 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 17 September 2022

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TUPA04

Sheet Electron Probe for Beam Tomography

proton, diagnostics, cathode, simulation

354

V.G. Dudnikov, M.A. Cummings, G. Dudnikova
Muons, Inc, Illinois, USA

Funding: Supported by DOE SBIR grant # DE-SC0021581.
We propose a new approach to electron beam tomography: we will generate a pulsed sheet of electrons. As the ion beam bunches pass through the sheet, they cause distortions in the distribution of sheet electrons arriving at a luminescent screen with a CCD device on the other side of the beam; these sheet electrons are interpreted to give a continuous measurement of the beam profile. The apparatus to generate the sheet beam is a strip cathode, which, compared to the scanning electron beam probe, is smaller, has simpler design and less expensive manufacturing, has better magnetic shielding, has higher sensitivity and higher resolution, has better accuracy of measurement, and has better time resolution.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA04

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Received ※ 22 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 10 August 2022

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TUPA11

Magnet System for a Compact Microtron Source

microtron, cavity, extraction, injection

363

S.A. Kahn, R.J. Abrams, M.A. Cummings, R.P. Johnson, G.M. Kazakevich
Muons, Inc, Illinois, USA

Funding: Work supported in part by U.S. D.O.E. SBIR grant DE-SC0013795.
A microtron can be an effective intense electron source. It can use less RF power than a linac to produce a similar energy because the beam will pass through the RF cavity several times. To produce a high-quality low-emittance beam with a microtron requires a magnetic system with a field uniformity $δ B/B<0.001. Field quality for a compact microtron with fewer turns is more difficult to achieve. In this study we describe the magnet for a compact S-band microtron that will achieve the necessary field requirements. The shaping of the magnet poles and shimming of the magnet iron at the outer extent of the poles will be employed to provide field uniformity. The extraction of the beam will be discussed.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA11

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Received ※ 04 August 2022 — Revised ※ 14 August 2022 — Accepted ※ 06 September 2022 — Issue date ※ 08 October 2022

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TUPA13

Affordable, Efficient Injection-Locked Magnetrons for Superconducting Cavities

cavity, injection, controls, GUI

366

M. Popovic, M.A. Cummings, R.P. Johnson, S.A. Kahn, R.R. Lentz, M.L. Neubauer, T. Wynn
Muons, Inc, Illinois, USA
T. Blassick, J.K. Wessel
Richardson Electronics Ltd, Lafox, Illinois, USA

Funding: DE-SC0022586.
Existing magnetrons that are typically used to study methods of control or lifetime improvements for SRF accelerators are built for much different applications such kitchen microwave ovens (1kW, 2.45 GHz) or industrial heating (100 kW, 915 MHz). In this project, Muons, Inc. will work with an industrial partner to develop fast and flexible manufacturing techniques to allow many ideas to be tested for construction variations that enable new phase and amplitude injection locking control methods, longer lifetime, and inexpensive refurbishing resulting in the lowest possible life-cycle costs. In Phase II magnetron sources will be tested on SRF cavities to accelerate an electron beam at JLab. A magnetron operating at 650 MHz will be constructed and tested with our novel patented subcritical voltage operation methods to drive an SRF cavity. The choice of 650 MHz is an optimal frequency for magnetron efficiency. The critical areas of magnetron manufacturing and design affecting life-cycle costs that will be modeled for improvement include: Q_ext, filaments, magnetic field, vane design, and novel control of outgassing.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA13

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Received ※ 05 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 23 August 2022

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TUPA14

Fast First-Order Spin Propagation for Spin Matching and Polarization Optimization with Bmad

polarization, quadrupole, lattice, solenoid

369

J.M. Asimow, G.H. Hoffstaetter, D. Sagan, M.G. Signorelli
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Accurate spin tracking is essential for the simulation and propagation of polarized beams, in which a majority of the particles’ spin point in the same direction. Bmad, an open-sourced library for the simulation of charged particle dynamics, traditionally tracks spin via integrating through each element of a lattice. While exceptionally accurate, this method has the drawback of being slow; at best, the runtime is proportional to the length of the element. By solving the spin transport equation for simple magnet elements, Bmad can reduce this algorithm to constant runtime while maintaining high accuracy. This method, known as "Sprint," enables quicker spin matching and prototyping of lattice designs via Bmad.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA14

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Received ※ 30 July 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 24 August 2022

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TUPA21

Hydrodynamic and Beam Dynamic Simulations of Ultra-Low Emittance Whole Beam Dumps in the Advanced Photon Source Storage Ring

simulation, experiment, photon, storage-ring

390

J.C. Dooling, M. Borland, A.M. Grannan, C.J. Graziani, Y. Lee, R.R. Lindberg, G. Navrotski
ANL, Lemont, Illinois, USA
N.M. Cook
RadiaSoft LLC, Boulder, Colorado, USA
D.W. Lee
UCSC, Santa Cruz, California, USA

Funding: Work supported by Accelerator Science and Technology LDRD Project 2021-0119 and the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source Upgrade will use a multi-bend achromatic lattice to reduce vertical and horizontal beam emittances by one- and two-orders of magnitude respectively; in addition operating current will double. The resulting electron beam will be capable of depositing more than 150 MGy on machine protection collimators creating high-energy-density conditions. Work is underway to couple the beam dynamics code Elegant with the particle-matter interaction program MARS and the magnetohydrodynamics code FLASH to model the effects of whole beam dumps on the collimators. Loss distributions from Elegant are input to MARS which provide dose maps to FLASH. We also examine the propagation of downstream shower components after the beam interacts with the collimator. Electrons and positrons are tracked to determine locations of beam loss. Beam dump experiments conducted in the APS storage-ring, generated dose levels as high as 30 MGy resulting in severe damage to the collimator surfaces with melting in the bulk. The deformed collimator surface may lead to beam deposition in unexpected locations. A fan-out kicker is planned to mitigate the effects of whole beam dumps on the collimators.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA21

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Received ※ 02 August 2022 — Revised ※ 10 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 10 September 2022

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TUPA28

Update on the Development of a Low-Cost Button BPM Signal Detector at AWA

pick-up, simulation, detector, electronics

409

W. Liu, G. Chen, D.S. Doran, S.Y. Kim, X. Lu, P. Piot, J.G. Power, C. Whiteford, E.E. Wisniewski
ANL, Lemont, Illinois, USA
E.E. Wisniewski
IIT, Chicago, Illinois, USA

Funding: Work supported by the US Department of Energy, Office of Science.
A single-pulse, high dynamic range, cost-effective BPM signal detector has been on the most wanted list of the Argonne Wakefield Accelerator (AWA) Test Facility for many years. The unique capabilities of the AWA beamline require BPM instrumentation with an unprecedented dynamic range, thus a cost-effective solution could be challenging to design and prototype. With the help of a better circuit model for a button BPM signal source, we are able to do the circuit simulations with more realistic input signals and make predictions much closer to realities. Our most recent design and prototype results are shared in this paper.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA28

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Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 09 October 2022

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TUPA32

SCU Ends Configured as Phase Shifter

undulator, simulation, FEL, quadrupole

420

M.F. Qian
ANL, Lemont, Illinois, USA

Funding: Work supported by LDRD funding from Argonne National Laboratory, provided by the Director, Office of Science, of the U.S. DOE under Contract No. DE-AC02-06CH11357.
Dipole correctors and phase shifters are usually needed in the interspace of a permanent magnet (PM)-based undulator array for purposes of beam steering and phase matching when the field strength is changing. Unlike the PM-based undulators, the superconducting undulator (SCU) can change its end field with the help of varying currents in the end coils. By setting the end coil currents the beam-steering and the phase-matching could be realized, thus eliminating the need for standalone correctors and phase shifters, saving the interspace as well as reducing the mechanical complexity of an undulator array. We developed a procedure for determining the SCU end coil currents and verified it by numerical simulations. The procedure as well as the simulation results are described in this paper.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA32

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Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 07 September 2022

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TUPA33

Magnetic Field Calculation of Superconducting Undulators for FEL Using Maxwell 3D

undulator, FEL, wiggler, laser

423

Y. Shiroyanagi, Y. Ivanyushenkov, M. Kasa
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
An ANL-SLAC collaboration is working on design of a planar superconducting undulator (SCU) demonstrator for a FEL. As a part of this project, a SCU magnet prototype is planned to be built and tested. A planar SCU magnet consisting of a 1.0-m-long segment is being designed. Although OPERA is a standard tool for magnetic field calculation, ANSYS Maxwell 3D can also be used for a large and complex geometry. An ANSYS calculated magnetic field was benchmarked with the measured field profile of existing SCUs. This paper presents calculations of magnetic field and field integrals of 0.5-m-long and 1.0-m-long planar SCUs with a new end correction scheme. Then, an external phase shifter is also incorporated into the model. A cross-talk between a phase shifter and SCU magnetic structures is also presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA33

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Received ※ 02 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 25 August 2022

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TUPA36

The Advanced Photon Source Linac Extension Area Beamline

gun, linac, photon, lattice

430

K.P. Wootton, W. Berg, J.M. Byrd, J.C. Dooling, G.I. Fystro, A.H. Lumpkin, Y. Sun, A. Zholents
ANL, Lemont, Illinois, USA
C.C. Hall
RadiaSoft LLC, Boulder, Colorado, USA

Funding: This research used resources of the Advanced Photon Source, operated for the U.S. Department of Energy Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
The Linac Extension Area at the Advanced Photon Source is a flexible beamline area for testing accelerator components and techniques. Driven by the Advanced Photon Source electron linac equipped with a photocathode RF electron gun, the Linac Extension Area houses a 12 m long beamline. The beamline is furnished with YAG screens, BPMs and a magnetic spectrometer to assist with characterization of beam emittance and energy spread. A 1.4 m long insertion in the middle of the beamline is provided for the installation of a device under test. The beamline is expected to be available soon for testing accelerator components and techniques using round and flat electron beams over an energy range 150-450 MeV. In the present work, we describe this beamline and summarise the main beam parameters.

Poster TUPA36 [0.892 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA36

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Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 19 September 2022

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TUPA38

Sublinear Intensity Response of Cerium-Doped Yttrium Aluminium Garnet Screen with Charge

booster, FEL, linac, storage-ring

437

K.P. Wootton, A.H. Lumpkin
ANL, Lemont, Illinois, USA

Funding: This research used resources of the Advanced Photon Source, operated for the U.S. Department of Energy Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
Swap-out injection to the Advanced Photon Source Upgrade storage ring necessitates the injection of ~17 nC electron bunches at 6 GeV. To aid with machine tune-up and to measure the beam size, diagnostic imaging screens are envisaged at several locations in the beam transport line from the booster synchrotron to the storage ring. As such, it is important to determine whether the response of these screens to charge is linear. In the present work, we examine the effect of sublinear intensity quenching of a Cerium-doped Yttrium-Aluminium-Garnet scintillator screen. A 1.3 megapixel FLIR BlackFly monochrome digital camera was used to image the beam at the scintillator. At 7 GeV beam energy, over the charge densities investigated (<10 fC um^-2), an approximately 10 % reduction of the imaging intensity due to quenching of the scintillator was observed.

Poster TUPA38 [0.557 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA38

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Received ※ 02 August 2022 — Accepted ※ 03 August 2022 — Issue date ※ 09 August 2022

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TUPA41

Applications of Machine Learning in Photo-Cathode Injectors

laser, controls, cathode, network

441

A. Aslam
UNM-ECE, Albuquerque, USA
M. Babzien
BNL, Upton, New York, USA
S. Biedron
Element Aero, Chicago, USA

To configure a photoinjector to reproduce a given electron bunch with the desired characteristics, it is necessary to adjust the operating parameters with high precision. More or less, the fine tunability of the laser parameters are of extreme importance as we try to model further applications of the photoinjector. The laser pulse incident on the photocathode critically affects the electron bunch 3D phase space. Parameters such as the laser pulse transverse shape, total energy, and temporal profile must be controlled independently, any laser pulse variation over both short and long-time scales also requires correction. The ability to produce arbitrary laser intensity distributions enables better control of electron bunch transverse and longitudinal emittance by affecting the space-charge forces throughout the bunch. In an accelerator employing a photoinjector, electron optics in the beamline downstream are used to transport, manipulate, and characterize the electron bunch. The adjustment of the electron optics to achieve a desired electron bunch at the interaction point is a much better understood problem than laser adjustment, so this research emphasizes laser shaping.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA41

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Received ※ 30 July 2022 — Revised ※ 12 August 2022 — Accepted ※ 13 August 2022 — Issue date ※ 07 September 2022

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TUPA52

Initial Results of the 201.25 MHz Coaxial Window Test Stand

multipactoring, Windows, vacuum, DTL

458

T.W. Hall, J.T.M. Lyles, A. Poudel, A.S. Waghmare
LANL, Los Alamos, New Mexico, USA

We have recently commissioned an RF window test stand for the Drift Tube Linear Accelerator (DTL) portion of the Los Alamos Neutron Science Center (LANSCE). The window test stand consists of two RF windows that create a vacuum chamber which allows the windows to be tested to the peak power levels used in the DTL. Initial results clearly indicated multipactoring due to the increase of pressure at specific regions of peak forward power levels. Temperature measured at various azimuthal locations on both windows showed increased multipactor heating on the downstream window versus the upstream window. We present the effect of the titanium nitride coating that is presently applied to windows on both multipactor and window temperature. These results are discussed with respect to their impact on the LANSCE DTL performance.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA52

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Received ※ 25 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 07 September 2022

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TUPA53

Modeling of Nonlinear Beam Dynamics via a Novel Particle-Mesh Method and Surrogate Models with Symplectic Neural Networks

simulation, network, radiation, synchrotron-radiation

462

C.-K. Huang, O. Beznosov, J.W. Burby, B.E. Carlsten, G.A. Dilts, J. Domine, R. Garimella, A. Kim, T.J. Kwan, H.N. Rakotoarivelo, R.W. Robey, B. Shen, Q. Tang
LANL, Los Alamos, New Mexico, USA
F.Y. Li
New Mexico Consortium, Los Alamos, USA

Funding: Work supported by the LDRD program at Los Alamos National Laboratory and the ASCR SciML program of DOE.
The self-consistent nonlinear dynamics of a relativistic charged particle beam, particularly through the interaction with its complete self-fields, is a fundamental problem underpinning many accelerator design issues in high brightness beam applications, as well as the development of advanced accelerators. A novel self-consistent particle-mesh code, CoSyR [1], is developed based on a Lagrangian method for the calculation of the beam particles’ radiation near-fields and associated beam dynamics. Our recent simulations reveal the slice emittance growth in a bend and complex interplay between the longitudinal and transverse dynamics that are not captured in the 1D longitudinal static-state Coherent Synchrotron Radiation (CSR) model. We further show that surrogate models with symplectic neural networks can be trained from simulation data with significant time-savings for the modeling of nonlinear beam dynamics effects. Possibility to extend such surrogate models for the study of spin-orbital coupling is also briefly discussed.
[1] C.-K. Huang et al., Nucl. Instruments Methods Phys. Res. Sect. A, vol. 1034, p. 166808, 2022.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA53

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Received ※ 25 July 2022 — Revised ※ 03 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 11 August 2022

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TUPA55

Progress Toward Improving Accelerator Performance and Automating Operations with Advanced Analysis Software

diagnostics, operation, cathode, software

465

J.E. Koglin, J.E. Coleman, M. McKerns, D. Ronquillo, A. Scheinker
LANL, Los Alamos, New Mexico, USA

Funding: Research presented in this conference paper was supported by the Laboratory Directed Research and Development program of Los Alamos National Laboratory under project numbers XXG2, XX8R and XXB6.
The penetrating radiography provided by the Dual Axis Radiographic Hydrodynamic Test (DARHT) facility is a key capability in executing a core mission of the Los Alamos National Laboratory (LANL). A new suite of software is being developed in the Python programming language to support operations of the of two DARHT linear induction accelerators (LIAs). Historical data, built as hdf5 data structures for over a decade of operations, are being used to develop automated failure and anomaly detection software and train machine learning models to assist in beam tuning. Adaptive machine learning (AML) that incorporate physics-based models are being designed to use non-invasive diagnostic measurements to address the challenge of time variation in accelerator performance and target density evolution. AML methods are also being developed for experiments that use invasive diagnostics to understand the accelerator behavior at key locations, the results of which will be fed back into the accelerator models. The status and future outlook for these developments will be reported, including how Jupyter notebooks are being used to rapidly deploy these advances as highly-interactive web applications.

Poster TUPA55 [1.919 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA55

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Received ※ 15 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 12 August 2022

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TUPA65

Machine Learning for the LANL Electromagnetic Isotope Separator

controls, dipole, ion-source, feedback

490

A. Scheinker, K.W. Dudeck, C.P. Leibman
LANL, Los Alamos, New Mexico, USA

Funding: Los Alamos National Laboratory Electromagnetic Isotope Separator Project.
The Los Alamos National Laboratory electromagnetic isotope separator (EMIS) utilizes a Freeman ion source to generate beams of various elements which are accelerated to 40 keV and passed through a 75-degree bend using a large dipole magnet with a radius of 1.2 m. The isotope mass differences translate directly to a spread in momentum, dp, relative to the design momentum p0. Momentum spread is converted to spread in the horizontal arrival location dx at a target chamber by the dispersion of the dipole magnet: dx = D(s)dp/p0. By placing a thin slit leading to a collection chamber at a location xc specific isotope mass is isolated by adjusting the dipole magnet strength or the beam energy. The arriving beam current at xc is associated with average isotope atomic mass, giving an isotope mass spectrum I(m) measured in mA. Although the EMIS is a compact system (5 m) setting up and automatically running at an optimal isotope separation profile I(m) profile is challenging due to time-variation of the complex source as well as un-modeled disturbances. We present preliminary results of developing adaptive machine learning-based tools for the EMIS beam and for the accelerator components.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA65

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Received ※ 18 July 2022 — Revised ※ 07 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 10 August 2022

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TUPA72

Comparison Study on First Bunch Compressor Schemes by Conventional and Double C-Chicane for MaRIE XFEL

dipole, emittance, FEL, radiation

496

H. Xu, P.M. Anisimov, L.D. Duffy, Q.R. Marksteiner
LANL, Los Alamos, New Mexico, USA

Funding: Laboratory Directed Research and Development program of Los Alamos National Laboratory, project number 20200287ER.
We report our comparison study on the first stage electron bunch compression schemes at 750 MeV using a conventional and a double C-chicane for the X-ray free electron laser (XFEL) under development for the Matter-Radiation Interactions in Extremes (MaRIE) initiative at Los Alamos National Laboratory. Compared to the performance of the conventional C-chicane bunch compressor, the double C-chicane scheme exhibits the capability of utilizing the transverse momentum shift induced by the coherent synchrotron radiation in the second C-chicane to compensate that generated in the first C-chicane, resulting in a compressed electron bunch with minimized transverse momentum shift along the beam. It is also found that the double C-chicane scheme can be designed to significantly better preserve the beam emittance in the course of the bunch compression. This is particularly beneficial for the MaRIE XFEL whose lasing performance critically depends on the preservation of the ultralow beam emittance.

Poster TUPA72 [1.339 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA72

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Received ※ 01 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 15 August 2022

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TUPA73

Design and Low Power Test of an Electron Bunching Enhancer Using Electrostatic Potential Depression

cavity, simulation, gun, experiment

499

H. Xu, B.E. Carlsten, Q.R. Marksteiner
LANL, Los Alamos, New Mexico, USA
B.L. Beaudoin, T.W. Koeth, A. Ting
UMD, College Park, Maryland, USA

Funding: This project was supported by the U.S. Department of Energy Office of Science through the Accelerator Stewardship Program.
We present our experimental design and low power test results of a structure for the proof-of-principle demonstration of fast increase of the first harmonic current content in a bunched electron beam, using the technique of electrostatic potential depression (EPD). A primarily bunched electron beam from an inductive output tube (IOT) at 710 MHz first enters an idler cavity, where the longitudinal slope of the beam energy distribution is reversed. The beam then transits through an EPD section implemented by a short beam pipe with a negative high voltage bias, inside which the rate of increase of the first harmonic current is significantly enhanced. An output cavity measures the harmonic current developed inside the beam downstream of the EPD section. Low power test results of the idler and the output cavities agree with the theoretical design.

Poster TUPA73 [1.307 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA73

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Received ※ 29 July 2022 — Accepted ※ 03 August 2022 — Issue date ※ 09 August 2022

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TUPA74

Numerical Calculations of Wave Generation from a Bunched Electron Beam in Space

plasma, radiation, simulation, experiment

502

H. Xu, G.L. Delzanno, L.D. Duffy, Q.R. Marksteiner, G.D. Reeves
LANL, Los Alamos, New Mexico, USA

Funding: This project was supported by the Laboratory Directed Research and Development program of Los Alamos National Laboratory.
We present our numerical approach and preliminary results of the calculations of whistler and X-mode wave generation by a bunched electron beam in space. The artificial generation of whistler and X-mode plasma waves in space is among the candidate techniques to accomplish the radiation belt remediation (RBR), in an effort to precipitate energetic electrons towards the atmosphere to reduce their threat to low-Earth orbit satellites. Free-space propagation of an electron pulse in a constant background magnetic field was simulated with the CST particle-in-cell (PIC) solver, with the temporal evolution of the beam recorded. The SpectralPlasmaSolver (SPS) was then modified to use the recorded electron pulse propagation to calculate the real-time plasma waves generated by the beam. SPS simulation results of the wave generation for the upcoming Beam-PIE experiment as well as an ideal bunched electron beam are shown.

Poster TUPA74 [0.963 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA74

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Received ※ 18 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 08 August 2022

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TUPA77

X-Band Harmonic Longitudinal Phase Space Linearization at the PEGASUS Photoinjector

cavity, linac, gun, laser

508

P.E. Denham, P. Musumeci, A. Ody
UCLA, Los Angeles, USA

Due to the finite bunch length, photoemitted electron beams sample RF-nonlinearities that lead to energy-time correlations along the bunch temporal profile. This is an important effect for all applications where the projected energy spread is important. In particular, for time-resolved single shot electron microscopy, it is critical to keep the beam energy spread below 1·10^-4 to avoid chromatic aberrations in the lenses. Higher harmonic RF cavities can be used to compensate for the RF-induced longitudinal phase space nonlinearities. Start-to-end simulations suggest that this type of compensation can reduce energy spread to the 1·10^-5 level. This work is an experimental study of x-band harmonic linearization of a beam longitudinal phase space at the PEGASUS facility, including developing high-resolution spectrometer diagnostics to verify the scheme.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA77

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Received ※ 25 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 10 August 2022

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TUPA81

Design of a High-Power RF Breakdown Test for a Cryocooled C-Band Copper Structure

cavity, cryogenics, GUI, distributed

516

G.E. Lawler, A. Fukasawa, J.R. Parsons, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
Z. Li, S.G. Tantawi
SLAC, Menlo Park, California, USA
A. Mostacci
Sapienza University of Rome, Rome, Italy
E.I. Simakov, T. Tajima
LANL, Los Alamos, New Mexico, USA
B. Spataro
LNF-INFN, Frascati, Italy

Funding: This work was supported by the DOE Contract DE-SC0020409.
High-gradient RF structures capable of maintaining gradients in excess of 250 MV/m are critical in several concepts for future electron accelerators. Concepts such as the ultra-compact free electron laser (UC-XFEL) and the Cool Copper Collider (C3) plan to obtain these gradients through the cryogenic operation (<77K) of normal conducting copper cavities. Breakdown rates, the most significant gradient limitation, are significantly reduced at these low temperatures, but the precise physics is complex and involves many interacting effects. High-power RF breakdown measurements at cryogenic temperatures are needed at the less explored C-band frequency (5.712 GHz), which is of great interest for the aforementioned concepts. On behalf of a large collaboration of UCLA, SLAC, LANL, and INFN, the first C-band cryogenic breakdown measurements will be made using a LANL RF test infrastructure. The 2-cell geometry designed for testing will be modifications of the distributed coupled reentrant design used to efficiently power the cells while staying below the limiting values of peak surface electric and magnetic fields.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA81

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Received ※ 29 July 2022 — Accepted ※ 02 August 2022 — Issue date ※ 08 August 2022

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TUPA83

Derivative-Free Optimization of Multipole Fits to Experimental Wakefield Data

wakefield, simulation, multipole, experiment

523

N. Majernik, G. Andonian, W.J. Lynn, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
P. Piot, T. Xu
Northern Illinois University, DeKalb, Illinois, USA

Funding: Department of Energy DE-SC0017648.
A method to deduce the transverse self-wakefields acting on a beam, based only on screen images, is introduced. By employing derivative-free optimization, the relatively high-dimensional parameter space can be efficiently explored to determine the multipole components up to the desired order. This technique complements simulations, which are able to directly infer the wakefield composition. It is applied to representative simulation results as a benchmark and also applied to experimental data on skew wake observations from dielectric slab structures.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA83

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Received ※ 02 August 2022 — Revised ※ 21 August 2022 — Accepted ※ 26 August 2022 — Issue date ※ 11 September 2022

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TUPA86

Simulations of Nanoblade Cathode Emissions with Image Charge Trapping for Yield and Brightness Analyses

brightness, laser, emittance, scattering

535

J.I. Mann, G.E. Lawler, J.B. Rosenzweig, B. Wang
UCLA, Los Angeles, California, USA
T. Arias, J.K. Nangoi
Cornell University, Ithaca, New York, USA
S.S. Karkare
Arizona State University, Tempe, USA

Funding: National Science Foundation Grant No. PHY-1549132
Laser-induced field emission from nanostructures as a means to create high brightness electron beams has been a continually growing topic of study. Experiments using nanoblade emitters have achieved peak fields upwards of 40 GV/m according to semi-classical analyses, begging further theoretical investigation. A recent paper has provided analytical reductions of the common semi-infinite Jellium system for pulsed incident lasers. We utilize these results to further understand the physics underlying electron rescattering-type emissions. We numerically evaluate this analytical solution to efficiently produce spectra and yield curves. The effect of space-charge trapping at emission may be simply included by directly modifying these spectra. Additionally, we use a self-consistent 1-D time-dependent Schrödinger equation with an image charge potential to study the same system as a more exact, but computationally costly, approach. With these results we may finally investigate the mean transverse energy and beam brightness at the cathode in these extreme regimes.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA86

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Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 03 September 2022

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TUPA87

Simulations for the Space Plasma Experiments at the SAMURAI Lab

plasma, simulation, experiment, radiation

539

P. Manwani, H.S. Ancelin, A. Fukasawa, G.E. Lawler, N. Majernik, B. Naranjo, J.B. Rosenzweig, Y. Sakai, O. Williams
UCLA, Los Angeles, California, USA
G. Andonian
RadiaBeam, Santa Monica, California, USA

Funding: This work was performed with support of the US Department of Energy under Contract No. DE-SC0017648 and DESC0009914, and the DARPA GRIT Contract 20204571
Plasma wakefield acceleration using the electron linear accelerator test facility, SAMURAI, can be used to study the Jovian electron spectrum due to the high energy spread of the beam after the plasma interaction. The SAMURAI RF facility which is currently being constructed and commissioned at UCLA, is is capable of producing beams with 10 MeV energy, 2 nC charge, and 200 fsec bunch lengths with a 4 um emittance. Particle-in-cell (PIC) simulations are used to study the beam spectrum that would be generated from plasma interaction. Experimental methods and diagnostics are discussed in this paper.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA87

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Received ※ 04 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 06 September 2022

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WEXD6

Electron Cloud Measurements in Fermilab Booster

booster, simulation, proton, laser

556

S.A.K. Wijethunga, J.S. Eldred, E. Pozdeyev, C.-Y. Tan
Fermilab, Batavia, Illinois, USA

Fermilab Booster synchrotron requires an intensity upgrade from 4.5×10¹² to 6.5×10¹² protons per pulse as a part of Fermilab’s Proton Improvement Plan-II (PIP-II). One of the factors which may limit the high-intensity performance is the fast transverse instabilities caused by electron cloud effects. According to the experience in the Recycler, the electron cloud gradually builds up over multiple turns in the combined function magnets and can reach final intensities orders of magnitude greater than in a pure dipole. Since the Booster synchrotron also incorporates combined function magnets, it is important to discover any existence of an electron cloud. And if it does, its effects on the PIP-II era Booster and whether mitigating techniques are required. As the first step, the presence or absence of the electron cloud was investigated using a gap technique. This paper presents experimental details and observations of the bunch-by-bunch tune shifts of beams with various bunch train structures at low and high intensities and simulation results conducted using PyECLOUD software.

Slides WEXD6 [4.483 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEXD6

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Received ※ 02 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 21 August 2022 — Issue date ※ 09 September 2022

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WEYD3

Positron Acceleration in Linear, Moderately Non-Linear and Non-Linear Plasma Wakefields

positron, plasma, collider, emittance

560

G.J. Cao, E. Adli
University of Oslo, Oslo, Norway
S. Corde
LOA, Palaiseau, France
S.J. Gessner
SLAC, Menlo Park, California, USA

Accelerating particles to high energies with high efficiency and beam quality is crucial in developing accelerator technologies. The plasma acceleration technique, providing unprecedented high gradients, is considered as a promising future technology. While important progress has been made in plasma-based electron acceleration in recent years, identifying a reliable acceleration technique for the positron counterpart would pave the way to a linear e⁺e⁻ collider for high-energy physics applications. In this work, we show further studies of positron beam quality in moderately non-linear (MNL)* plasma wakefields. With a positron bunch of initial energy 1 GeV, emittance preservation can be achieved in optimised scenarios at 2.38 mm’mrad. In parallel, asymmetric beam collisions at the interaction point (IP) are studied to evaluate the current luminosity reach and provide insight to improvements required for positron acceleration in plasma. It is necessary to scale down the emittance of the positron bunch. In the MNL regime, a positron beam with 238 ’m’mrad level emittance implies compromise in charge or necessity for ultra-short bunches.
* "Efficiency and beam quality for positron acceleration in loaded plasma wakefields",C. S. Hue, G. J. Cao, et.al Phys. Rev. Research 3, 043063

Slides WEYD3 [3.635 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEYD3

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Received ※ 01 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 24 August 2022

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WEYE4

Electron Cloud Simulations in the Fermilab Recycler

simulation, software, proton, optics

581

A.P. Schreckenberger
University of Illinois at Urbana-Champaign, Urbana, USA
R. Ainsworth
Fermilab, Batavia, Illinois, USA

We present a simulation study to characterize the stability region of the Fermilab Recycler Ring in the context of secondary emission yield (SEY). Interactions between electrons and beam pipe material can produce electron clouds that jeopardize beam stability in certain focusing configurations. Such an instability was documented in the Recycler, and the work presented here reflects improvements to better understand that finding. We incorporated the Furman-Pivi Model into a PyECLOUD analysis, and we determined the instability threshold given various bunch lengths, beam intensities, SEY magnitudes, and model parameters.

Slides WEYE4 [2.096 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEYE4

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Received ※ 01 August 2022 — Revised ※ 06 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 30 September 2022

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WEYE6

Thermionic Sources for Electron Cooling at IOTA

vacuum, cathode, proton, space-charge

588

M.K. Bossard, Y.K. Kim
University of Chicago, Chicago, Illinois, USA
N. Banerjee, J.A. Brandt
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
B.L. Cathey, S. Nagaitsev, G. Stancari
Fermilab, Batavia, Illinois, USA
M.A. Krieg
Saint Olaf College, Northfield, MN, USA

We are planning a new electron cooling experiment at the Integrable Optics Test Accelerator (IOTA) at Fermilab for cooling ~2.5 MeV protons in the presence of intense space-charge. Here we present the simulations and design of a thermionic electron source for cooling at IOTA. We particularly discuss parameters of the thermionic source electrodes, as well as the simulation results. We also present a new electron source test-stand at the University of Chicago, which will be used to test the new thermionic electron source, as well as other electron sources. In addition, we discuss results from analyzing the test stand operations with a currently existing electron source. Furthermore, we present future steps for the test stand as well as production and commissioning of the thermionic source at IOTA.

Slides WEYE6 [3.182 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEYE6

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Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 28 August 2022

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WEZD1

ARDAP’s Perspective on Accelerator Technology R&D in the U.S.

operation, collider, laser, controls

592

B.E. Carlsten, E.R. Colby, R.A. Marsh, M. White
ARDAP, Washington, USA

DOE operates several particle accelerator facilities and is planning several new forward-leaning accelerator facilities over the next decade or two. These new facilities will focus on discovery science research and fulfilling other core DOE missions. Near and mid-term examples include PIP-II and FACET-II (for High Energy Physics); LCLS-II, SNS-PPU, APS-U, and ALS-U (for Basic Energy Sciences); FRIB (for Nuclear Physics); NSTX-U and MPEX (for Fusion Energy Sciences); and Scorpius (for NNSA). Longer-term examples may include future colliders, the SNS-STS, LCLS-II HE, and EIC. In addition to domestic facilities, DOE’s Office of Science (SC) also contributes to several international efforts. Together, these new facilities constitute a multibillion-dollar construction and operations investment. To be successful, they will require advances in state-of-the-art accelerator technologies. They will also require the National Laboratories to procure a variety of accelerator components. This paper summarizes how DOE is working to address these upcoming R&D and accelerator component production needs through its new office of Accelerator R&D and Production (ARDAP).

Slides WEZD1 [2.310 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEZD1

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Received ※ 05 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 19 August 2022

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WEZD6

Manufacturing the Harmonic Kicker Cavity Prototype for the Electron-Ion Collider

cavity, kicker, collider, MMI

601

S.A. Overstreet, M.W. Bruker, G.A. Grose, J. Guo, J. Henry, G.-T. Park, R.A. Rimmer, H. Wang, R.S. Williams
JLab, Newport News, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177
High-bunch-frequency beam-separation schemes, such as the injection scheme proposed for the Rapid Cycling Synchrotron at the Electron-Ion Collider, demand rise and fall times an order of magnitude below what can realistically be accomplished with a stripline kicker. Nanosecond-time-scale kick waveforms can instead be obtained by Fourier synthesis in a harmonically resonant quarter-wave radio-frequency cavity which is optimized for high shunt impedance. Originally developed for the Jefferson Lab Electron-Ion Collider (JLEIC) Circulator Cooler Ring, a hypothetical 11-pass ring driven by an energy-recovery linac at Jefferson Lab, our high-power prototype of such a harmonic kicker cavity, which operates at five modes at the same time, will demonstrate the viability of this concept with a beam test at Jefferson Lab. As the geometry of the cavity, tight mechanical tolerances, and number of ports complicate the design and manufacturing process, special care must be given to the order of the manufacturing steps. We present our experiences with the manufacturability of the present design, lessons learned, and first RF test results from the prototype.

Slides WEZD6 [12.312 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEZD6

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Received ※ 04 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 18 August 2022 — Issue date ※ 31 August 2022

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WEZE3

Compact, High-Power Superconducting Electron Linear Accelerators for MW Industrial Applications

cavity, SRF, vacuum, gun

604

J.C.T. Thangaraj, R. Dhuley
Fermilab, Batavia, Illinois, USA

Fermilab has developed a novel concept for an industrial electron linac using Nb₃Sn coating technology and conduction cooling. We will show the range of multi-cavity linac designs targeted toward various applications. We will also discuss technology development status with results on conduction cooling of SRF cavities based on cryocoolers, which removes the need for liquid Helium, thus making SRF technology accessible to industrial applications. These conduction-cooled linacs can generate electron beam energies up to 10 MeV in continuous-wave operation and can reach higher power (>=1 MW) by combing several modules. Compact and light enough to mount on mobile platforms, our machine is anticipated to enable new in-situ environmental remediation applications such as waste-water treatment for urban areas, X-ray medical device sterilization, and innovative pavement applications. We also show cost-economics and key R&D areas that much be addressed for a practical machine.

Slides WEZE3 [3.811 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEZE3

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Received ※ 02 August 2022 — Revised ※ 12 August 2022 — Accepted ※ 13 August 2022 — Issue date ※ 30 August 2022

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WEPA01

Beam Dynamics Optimization of a Low Emittance Photoinjector Without Buncher Cavities

emittance, cavity, cathode, gun

615

J. Qiang
LBNL, Berkeley, California, USA
F. Ji, T.O. Raubenheimer
SLAC, Menlo Park, California, USA

The photoinjector plays an important role in generating high brightness low emittance electron beam for x-ray free electron laser applications. In this paper, we report on beam dynamics optimization study of a low emittance photoinjector based on a proposed superconducting gun without including any buncher cavities. Multi-objective optimization with self-consistent beam dynamics simulations was employed to attain the optimal Pareto front.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA01

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Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 11 September 2022

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WEPA08

Design and Operation Experience of a Multi-Collimator/YAG Screen Device on LCLS II Low Energy Beamline

wakefield, simulation, radiation, gun

631

X. Liu, C. Adolphsen, M. Santana-Leitner, L. Xiao, F. Zhou
SLAC, Menlo Park, California, USA

During the commissioning of the normal conducting VHF RF gun of LCLS II, it was observed that field emission (dark current) of roughly 2 µA level was present under normal operation of the gun. While the dark current of this level is deemed manageable with existing beamline configurations, it is desired in precaution to add a collimator on the low energy beamline to block the dark current, being concerned that the dark current situation might worsen with time. Since no spare longitudinal space is available, the new device takes place of the existing YAG screen. The new device is made of a 15 mm thick copper plate, with four round apertures of 6, 8, 10, and 12 mm radius respectively. At the end of the collimator plate, features are made for clamping two YAG screens and mounting their corresponding mirrors for beam/halo profile imaging. The collimator plate is electrically insulated from the chamber so that it can also be used for measuring the dark current. A motor-driven UHV compatible linear translator shifts the device between positions. Besides design details, related thermal, beam dynamics, and radiation analyses as well as operation experience will be presented.

* Work supported by US DOE under contract AC02-76SF00515.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA08

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Received ※ 02 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 13 September 2022

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WEPA13

New Results at JLab Describing Operating Lifetime of GaAs Photo-guns

gun, cathode, laser, experiment

644

M.W. Bruker, J.M. Grames, C. Hernandez-Garcia, M. Poelker, S. Zhang
JLab, Newport News, Virginia, USA
V.M. Lizárraga-Rubio, C.A. Valerio-Lizárraga
ECFM-UAS, Culiacan, Sinaloa, Mexico
J.T. Yoskowitz
ODU, Norfolk, Virginia, USA

Funding: This work is supported by U.S. Department of Energy under DE-AC05-06OR23177 and by Consejo Nacional de Ciencia y Tecnología and the Universidad Autonoma de Sinaloa under PRO_A1_022.
Polarized electrons from GaAs photocathodes have been key to some of the highest-impact results of the Jefferson Lab science program over the past 30 years. During this time, various studies have given insight into improving the operational lifetime of these photocathodes in DC high-voltage photo-guns while using lasers with spatial Gaussian profiles of typically 0.5 mm to 1 mm FWHM, cathode voltages of 100 kV to 130 kV, and a wide range of beam currents up to multiple mA. In this contribution, we show recent experimental data from a 100 kV to 180 kV setup and describe our progress at predicting the lifetime based on the calculable dynamics of ionized gas molecules inside the gun. These new experimental studies at Jefferson Lab are specifically aimed at exploring the ion damage of higher-voltage guns being built for injectors.

Poster WEPA13 [1.644 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA13

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Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 01 October 2022

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WEPA15

High-Field Design Concept for Second Interaction Region of the Electron-Ion Collider

collider, luminosity, proton, detector

648

B.R. Gamage, R. Ent, R. Rajput-Ghoshal, T. Satogata, A. Seryi, W. Wittmer, Y. Zhang
JLab, Newport News, Virginia, USA
D. Arbelaez, P. Ferracin, G.L. Sabbi
LBNL, Berkeley, California, USA
E.C. Aschenauer, J.S. Berg, H. Witte
BNL, Upton, New York, USA
V.S. Morozov
ORNL RAD, Oak Ridge, Tennessee, USA
F. Savary
CERN, Meyrin, Switzerland
P.N. Vedrine
CEA-DRF-IRFU, France
A.V. Zlobin
Fermilab, Batavia, Illinois, USA

Funding: Contract No. DE-AC05-06OR23177, Contract No. DE-SC0012704 and Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.
Efficient realization of the scientific potential of the Electron Ion Collider (EIC) calls for addition of a future second Interaction Region (2nd IR) and a detector in the RHIC IR8 region after the EIC project completion. The second IR and detector are needed to independently cross-check the results of the first detector, and to provide measurements with complementary acceptance. The available space in the existing RHIC IR8 and maximum fields achievable with NbTi superconducting magnet technology impose constraints on the 2nd IR performance. Since commissioning of the 2nd IR is envisioned in a few years after the first IR, such a long time frame allows for more R&D on the Nb₃Sn magnet technology. Thus, it could provide a potential alternative technology choice for the 2nd IR magnets. Presently, we are exploring its potential benefits for the 2nd IR performance, such as improvement of the luminosity and acceptance, and are also assessing the technical risks associated with use of Nb₃Sn magnets. In this paper, we present the current progress of this work.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA15

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Received ※ 04 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 17 August 2022 — Issue date ※ 31 August 2022

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WEPA16

A 500 kV Inverted Geometry Feedthrough for a High Voltage DC Electron Gun

gun, high-voltage, power-supply, cathode

651

C. Hernandez-Garcia, D.B. Bullard, J.M. Grames, G.G. Palacios Serrano, M. Poelker
JLab, Newport News, Virginia, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and Office of Science Funding Opportunity LAB 20-2310 award PAMS-254442.
The Continuous Electron Beam Accelerator Facility injector at Jefferson Lab (JLab) utilizes an inverted-geometry ceramic insulator photogun operating at 130 kV direct current to generate spin-polarized electron beams for high-energy nuclear physics experiments. A second photogun delivers 180 keV beam for commissioning a SRF booster in a testbed accelerator, and a larger version delivers 300 keV magnetized beam in a test stand beam line. This contribution reports on the development of an unprecedented inverted-insulator with cable connector for reliably applying 500 kV DC to a future polarized beam photogun, to be designed for operating at 350 kV without field emission. Such a photogun design could then be used for generating a polarized electron beam to drive a spin-polarized positron source as a demonstrator for high energy nuclear physics at JLab. There are no commercial cable connectors that fit the large inverted insulators required for that voltage range. Our proposed concept is based on a modified epoxy receptacle with intervening SF6 layer and a test electrode in a vacuum vessel.

Poster WEPA16 [6.217 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA16

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Received ※ 03 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 09 October 2022

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WEPA17

Improved Electrostatic Design of the Jefferson Lab 300 kV DC Photogun and the Minimization of Beam Deflection

gun, cathode, high-voltage, laser

655

M.A. Mamun, D.B. Bullard, J.M. Grames, C. Hernandez-Garcia, G.A. Krafft, M. Poelker, R. Suleiman
JLab, Newport News, Virginia, USA
J.R. Delayen, G.A. Krafft, G.G. Palacios Serrano, S.A.K. Wijethunga
ODU, Norfolk, Virginia, USA

Funding: This work is supported by the Department of Energy, under contract DE-AC05-06OR23177, JSA initiatives fund program, and the Laboratory Directed Research and Development program.
An electron beam with high bunch charge and high repetition rate is required for electron cooling of the ion beam to achieve the high luminosity required for the proposed electron-ion colliders. An improved design of the 300 kV DC high voltage photogun at Jefferson Lab was incorporated toward overcoming the beam loss and space charge current limitation experienced in the original design. To reach the bunch charge goal of ~ few nC within 75 ps bunches, the existing DC high voltage photogun electrodes and anode-cathode gap were modified to increase the longitudinal electric field (Ez) at the photocathode. The anode-cathode gap was reduced to increase the Ez at the photocathode, and the anode aperture was spatially shifted with respect to the beamline longitudinal axis to minimize the beam deflection introduced by the geometric asymmetry of the inverted insulator photogun. The electrostatic design and beam dynamics simulations were performed to determine the required modification. Beam-based measurement from the modified gun confirmed the reduction of the beam deflection, which is presented in this contribution.

Poster WEPA17 [2.973 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA17

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Received ※ 23 July 2022 — Revised ※ 28 July 2022 — Accepted ※ 05 August 2022 — Issue date ※ 11 August 2022

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WEPA20

High-Gradient Wien Spin Rotators at Jefferson Lab

vacuum, operation, high-voltage, gun

662

G.G. Palacios Serrano, P.A. Adderley, J.M. Grames, C. Hernandez-Garcia, M. Poelker
JLab, Newport News, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Nuclear physics experiments performed in the Contin-uous Electron Beam Accelerator Facility (CEBAF) at Jefferson Laboratory (JLab) require spin manipulation of electron beams. Two Wien spin rotators in the injector keV region are essential at CEBAF to establish longitudinal polarization at the end station target, and to flip the polarization direction by π rad to rule out false asymmetries. In a Wien filter, the homogeneous and independent electric and magnetic fields, along with the velocity vectors of the electrons that traverse it, form a mutually orthogonal system. The magnitude of the electrostatic field, established by biasing two highly-polished elec-trodes, defines the desired spin angle at the target yet deviates the beam trajectory due to the Lorentz force. The beam trajectory in the Wien is then re-established by adjusting the magnetic field, induced by an electromag-net encasing the device vacuum chamber. This contribu-tion describes the evolution design and high voltage testing of Wien filters for spin manipulation at increased beam energies in the keV injector region, required by high precision parity violation experiments like MOLLER.

Poster WEPA20 [1.434 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA20

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Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 05 September 2022

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WEPA22

Measuring the Electric Dipole Moment of the Electron in a Two-Energy Spin-Transparent Storage Ring

dipole, storage-ring, polarization, experiment

665

R. Suleiman, Y.S. Derbenev
JLab, Newport News, Virginia, USA
V.S. Morozov
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and by UT-Battelle, LLC, under contract DE-AC05-00OR22725.
We will present a new design of a two-energy storage ring for low energy (0.2 to 2 MeV) polarized electron bunches [1]. The new design is based on the transparent spin methodology that cancels the spin precession due to the magnetic dipole moment at any energy while allowing for spin precession induced by the fundamental physics of interest to accumulate. The buildup of the vertical component of beam polarization can be measured using standard Mott polarimetry that is optimal at low electron energy. These rings can be used to measure the permanent electric dipole moment of the electron, relevant to CP violation and matter-antimatter asymmetry in the universe, and to search for dark energy and ultra-light dark matter.
[1] R. Suleiman, V.S. Morozov, and Y.S. Derbenev, On possibilities of high precision experiments in fundamental physics in storage rings of low energy polarized electron beams, arXiv:2105.11575 (2021)

Poster WEPA22 [0.781 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA22

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Received ※ 04 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 07 October 2022

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WEPA24

pyJSPEC - A Python Module for IBS and Electron Cooling Simulation

simulation, emittance, scattering, experiment

672

H. Zhang, S.V. Benson, M.W. Bruker, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
The intrabeam scattering is an important collective effect that can deteriorate the property of a high-intensity beam and electron cooling is a method to mitigate the IBS effect. JSPEC (JLab Simulation Package on Electron Cooling) is an open-source C++ program developed at Jefferson Lab, which simulates the evolution of the ion beam under the IBS and/or the electron cooling effect. The Python wrapper of the C++ code, pyJSPEC, for Python 3.x environment has been recently developed and released. It allows the users to run JSPEC simulations in a Python environment. It also makes it possible for JSPEC to collaborate with other accelerator and beam modeling programs as well as plentiful python tools in data visualization, optimization, machine learning, etc. In this paper, we will introduce the features of pyJSPEC and demonstrate how to use it with sample codes and numerical results.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA24

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Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 26 August 2022

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WEPA26

197 MHz Waveguide Loaded Crabbing Cavity Design for the Electron-Ion Collider

cavity, HOM, GUI, impedance

679

S.U. De Silva, J.R. Delayen
ODU, Norfolk, Virginia, USA
J. Guo, R.A. Rimmer
JLab, Newport News, Virginia, USA
Z. Li
SLAC, Menlo Park, California, USA
B.P. Xiao
BNL, Upton, New York, USA

The Electron-Ion Collider will require crabbing systems at both hadron and electron storage rings in order to reach the desired luminosity goal. The 197 MHz crab cavity system is one of the critical rf systems of the col-lider. The crab cavity, based on the rf-dipole design, ex-plores the option of waveguide load damping to suppress the higher order modes and meet the tight impedance specifications. The cavity is designed with compact dog-bone waveguides with transitions to rectangular wave-guides and waveguide loads. This paper presents the compact 197 MHz crab cavity design with waveguide damping and other ancillaries.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA26

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Received ※ 08 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 06 September 2022

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WEPA31

Lower Temperature Annealing of Vapor Diffused Nb₃Sn for Accelerator Cavities

cavity, SRF, superconductivity, experiment

695

J.K. Tiskumara, J.R. Delayen
ODU, Norfolk, Virginia, USA
G.V. Eremeev
Fermilab, Batavia, Illinois, USA
U. Pudasaini
JLab, Newport News, Virginia, USA

Nb₃Sn is a next-generation superconducting material for the accelerator cavities with higher critical temperature and superheating field, both twice compared to Nb. It promises superior performance and higher operating temperature than Nb, resulting in significant cost reduction. So far, the Sn vapor diffusion method is the most preferred and successful technique to coat niobium cavities with Nb₃Sn. Although several post-coating techniques (chemical, electrochemical, mechanical) have been explored to improve the surface quality of the coated surface, an effective process has yet to be found. Since there are only a few studies on the post-coating heat treatment at lower temperatures, we annealed Nb₃Sn-coated samples at 800 C - 1000 C to study the effect of heat treatments on surface properties, primarily aimed at removing surface Sn residues. This paper discusses the systematic surface analysis of coated samples after annealing at temperatures between 850 C and 950 C.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA31

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Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 02 September 2022

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WEPA38

Progress on Machine Learning for the SNS High Voltage Converter Modulators

network, klystron, linac, simulation

715

M.I. Radaideh, S.M. Cousineau, D. Lu
ORNL, Oak Ridge, Tennessee, USA
T.J. Britton, K. Rajput, M. Schram, L.S. Vidyaratne
JLab, Newport News, Virginia, USA
G.C. Pappas, J.D. Walden
ORNL RAD, Oak Ridge, Tennessee, USA

The High-Voltage Converter Modulators (HVCM) used to power the klystrons in the Spallation Neutron Source (SNS) linac were selected as one area to explore machine learning due to reliability issues in the past and the availability of large sets of archived waveforms. Progress in the past two years has resulted in generating a significant amount of simulated and measured data for training neural network models such as recurrent neural networks, convolutional neural networks, and variational autoencoders. Applications in anomaly detection, fault classification, and prognostics of capacitor degradation were pursued in collaboration with the Jefferson Laboratory, and early promising results were achieved. This paper will discuss the progress to date and present results from these efforts.

Poster WEPA38 [1.320 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA38

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Received ※ 25 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 03 October 2022

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WEPA42

A Modular X-Ray Detector for Beamline Diagnostics at LANL

detector, DTL, diagnostics, shielding

725

P.M. Freeman, B. Odegard, R. Schmitz, D. Stuart, J. Yang
UCSB, Santa Barbara, California, USA
J. Bohon, M.S. Gulley, E.-C. Huang, J. Smedley
LANL, Los Alamos, New Mexico, USA
L. Malavasi
WPI, Worcester, MA, USA

An X-ray detector is being developed for diagnostic measurement and monitoring of the Drift Tube LINAC (DTL) at the Los Alamos Neutron Science Center (LANSCE) at Los Alamos National Lab. The detector will consist of a row of x-ray spectrometers adjacent to the DTL that will measure the spectrum of X-rays resulting from bremsstrahlung of electrons created in vacuum by the RF. Each spectrometer will monitor a specific gap between drift tubes, and will consist of an array of scintillating crystals coupled to SiPMs read out with custom-built electronics. The spectrometer is designed with one LYSO and three NaI crystals. The LYSO provides a tagged gamma source with three peaks that are used for calibration of the NaI. A prototype of the spectrometer was tested at the LANSCE DTL to validate the feasibility of measuring gamma spectra and performing self-calibration in situ. A summary of test results with the LANSCE prototype will be presented, along with a detector system design that aims to be modular and inexpensive across all modules in the DTL. Plans for future development will be presented as well.

Poster WEPA42 [1.308 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA42

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Received ※ 04 August 2022 — Revised ※ 06 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 11 August 2022

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WEPA43

Self-Contained Linac Irradiator for the Sterile Insect Technique (SIT)

target, linac, simulation, quadrupole

728

A. Diego, R.B. Agustsson, R.D. Berry, S. Boucher, O. Chimalpopoca, S.V. Kutsaev, A.Yu. Smirnov, V.S. Yu
RadiaBeam, Santa Monica, California, USA
S.J. Coleman
RadiaSoft LLC, Boulder, Colorado, USA

Funding: This work was financed by the US department of energy SBIR grant no. DE- SC0020010.
A 3-MeV X-band linac has been developed employing a cost-effective split structure design in order to replace radioactive isotope irradiators currently used for the Sterile Insect Technique (SIT) and other applications. The penetration of a Co-60 irradiator can be matched with Bremsstrahlung produced by a 3-MeV electron beam. The use of electron accelerators eliminates security risks and hazards inherent with radioactive sources. We present the current state of this X-band split structure linac and the rest of the irradiator system.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA43

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Received ※ 04 August 2022 — Revised ※ 06 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 16 September 2022

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WEPA44

Compact Inter-Undulator Diagnostic Assembly for TESSA-515

undulator, quadrupole, radiation, diagnostics

732

T.J. Hodgetts, R.B. Agustsson, Y.C. Chen, A.Y. Murokh, M. Ruelas
RadiaBeam, Santa Monica, California, USA
P.E. Denham, A.C. Fisher, J. Jin, P. Musumeci, Y. Park
UCLA, Los Angeles, USA

Funding: DOE grant DE-SC0009914, DE-SC0018559, and DE-SC0017102.
Beamline space is a very expensive and highly sought-after commodity, which makes the creation of compact integrated optics and diagnostics extremely valuable. The FAST- GREENS experimental program aims at demonstrating 10 % extraction efficiency from a relativistic electron beam using four helical undulators operating in the high gain TESSA regime. The inter-undulator gap needs to be as short as possible (17 cm in the current plans) to maximize the output power. Within this short distance, we needed to fit two focusing quadrupoles, a variable strength phase shifter, a transverse profile monitor consisting of a YAG-OTR combination for co-aligning the electron beam and laser, and an ion pump. By making the quadrupoles tunable with a variable gradient, in combination with vertical displacement, we can meet the optics requirements of matching the beam transversely to the natural focusing of the undulators. The two quadrupoles in conjunction with the electromagnetic dipole also serve as a phase shifter to realign the radiation and the bunching before each undulator section. This paper will discuss the mechanical design of this inter-undulator break section and its components.

Poster WEPA44 [0.752 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA44

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Received ※ 27 July 2022 — Revised ※ 03 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 11 August 2022

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WEPA45

Practical Review on Beam Line Commissioning Procedures and Techniques for Scientific and Industrial Electron Accelerators

MMI, emittance, operation, linac

735

M.O. Kravchenko, R.D. Berry, A. Diego, D.I. Gavryushkin, M. Ruelas
RadiaBeam, Santa Monica, California, USA

Accelerator science has a constant demand requiring improved electron beam quality for both scientific and industrial applications. Examples of parameters on existing systems that affect overall beam quality include: vacuum stability, component level alignment, RF phase matching, electron injection parameters, etc. A proper beam commissioning process allows the characterization of initial parameters that tune system setup appropriately in order to improve net beam quality and becomes a valuable source of data to guide system operation. Here we will discuss methods and possible obstacles during the commissioning process of accelerator systems experienced at RadiaBeam. This includes a description of the diagnostic equipment that may be used to commission a beam line such as: current transformers, faraday cups, profile monitors and pyro detectors. The interpretation of raw data from the diagnostics in terms of usefulness for further adjustments and improvements on the beam line as shown in current work. Simulations and empirical comparisons are also presented as examples for commissioning procedures within the aspect of expectations and actual results.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA45

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Received ※ 30 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 09 August 2022

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WEPA56

Encapsulation of Photocathodes Using High Power Pulsed RF Sputtering of hBN

cathode, simulation, vacuum, ion-effects

760

A. Liu, J.R. Callahan, S. Poddar
Euclid TechLabs, Solon, Ohio, USA
J.P. Biswas, M. Gaowei
BNL, Upton, New York, USA

Funding: This work is supported by the US DOE SBIR program under contract number DE-SC0021511 and DE-SC0020573.
Photocathodes of various materials are used in photoinjectors for generating photoelectron beams. Of particular interest are the alkali antimonides because of their ultra-high quantum efficiency (QE) and relatively low requirements for growth, and metallic materials such as Cu and Mg which have lower QE but are easier to maintain and have longer lifetime. The biggest challenge of using the alkali antimonide photocathode is that it has an extremely stringent requirement on vacuum and is destroyed rapidly by residual air in the system, while exposure of Mg and Cu in air also impacts the photocathode performance because of the oxidation. The photocathode can be protected against harmful gas molecules by using one or two monolayers of a 2D material such as graphene or hexagonal boron nitride (hBN). Furthermore, hBN monolayers even have the potential to improve the QE of the photocathode when working as the encapsulation thin-film. In this paper, we will discuss the feasibility of coating a photocathode with hBN by high power pulsed RF sputtering by using metallic photocathodes as examples, and compare the performance with encapsulated photocathodes with transferred hBN thin-films.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA56

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Received ※ 31 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 10 August 2022

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WEPA62

Design and Commissioning of the ASU CXLS RF System

klystron, laser, timing, linac

764

B.J. Cook, G.I. Babic, J.R.S. Falconer, W.S. Graves, M.R. Holl, S.P. Jachim, R.E. Larsen
Arizona State University, Tempe, USA

Funding: This work was supported in part by NSF award #1935994.
The Compact X-ray Light Source (CXLS) uses inverse Compton scattering of a high intensity laser off a bright, relativistic electron beam to produce hard x-rays. The accelerator consists of a photoinjector and three standing-wave linac sections, which are powered by two 6-MW klystrons operating at 9.3 GHz with a repetition rate of 1 kHz. This paper presents the design and commissioning of the CXLS RF systems consisting of both high-power RF structures and low-power diagnostics. The high-power RF system is comprised of two solid state amplifier and klystron modulator sets, various directional couplers, and three phase shifter power dividers. The low-level system consists of a master oscillator and laser phase lock, IQ modulators, IQ demodulators, and downconverters. We present measurements of the low-level and high-power RF phase and amplitude stability showing RMS timing jitter in the tens of femtoseconds and amplitude jitter below 0.1% at high power.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA62

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Received ※ 29 July 2022 — Revised ※ 03 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 19 August 2022

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WEPA65

On-Chip Photonics Integrated Photocathodes

GUI, photon, cathode, coupling

773

A.H. Kachwala, O. Chubenko, S.S. Karkare
Arizona State University, Tempe, USA
R. Ahsan
USC, Los Angeles, California, USA
H.U. Chae, R. Kapadia
University of Southern California, Los Angeles, California, USA

Funding: This work is supported by the NSF Center for Bright Beams under award PHY-1549132, and by the Department of Energy, Office of Science under awards DE-SC0021092, and DE-SC0021213.
Photonics integrated photocathodes can result in advanced electron sources for various accelerator applications. In such photocathodes, light can be directed using waveguides and other photonic components on the substrate underneath a photoemissive film to generate electron emission from specific locations at sub-micron scales and at specific times at 100-femtosecond scales along with triggering novel photoemission mechanisms resulting in brighter electron beams and enabling unprecedented spatio-temporal shaping of the emitted electrons. In this work we have demonstrated photoemission confined in the transverse direction using a nanofabricated Si₃N₄ waveguide underneath a 40-nm thick cesiated GaAs photoemissive film, thus demonstrating a proof of principle feasibility of such photonics integrated photocathodes. This work paves the way to integrate the advances in the field of photonics and nanofabrication with photocathodes to develop better electron sources.

Poster WEPA65 [0.642 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA65

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Received ※ 26 July 2022 — Revised ※ 06 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 10 August 2022

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WEPA66

Near-Threshold Photoemission from Graphene Coated Cu Single Crystals

cathode, experiment, cryogenics, brightness

776

C.J. Knill, S.S. Karkare
Arizona State University, Tempe, USA
H. Ago, K. Kawahara
Global Innovation Center, Kyushu University, Kasuga, Fukuoka, Japan
E. Batista, N.A. Moody, G.X. Wang, H. Yamaguchi, P. Yang
LANL, Los Alamos, New Mexico, USA

Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams, and by the Department of Energy under Grant DE-SC0021092.
The brightness of electron beams emitted from photocathodes plays a key role in the performance of x-ray free electron lasers (XFELs) and ultrafast electron diffraction (UED) experiments. In order to achieve the maximum beam brightness, the electrons need to be emitted from photocathodes with the smallest possible mean transverse energy (MTE). Recent studies have looked at the effect that a graphene coating has on the quantum efficiency (QE) of the cathode [1]. However, there have not yet been any investigations into the effect that a graphene coating has on the MTE. Here we report on MTE and QE measurements of a graphene coated Cu(110) single crystal cathode at room and cryogenic temperatures. At room temperature, a minimum MTE of 25 meV was measured at 295 nm. This MTE remained stable at 25 meV over several days. At 77 K, the minimum MTE of 9 meV was measured at 290 nm. We perform density functional theory (DFT) calculations to look at the effects of a graphene coating on a Cu(111) surface state. These calculations show that the graphene coating reduces the radius of the surface state, allowing for emission from a lower transverse energy state in comparison to bare Cu(111).
[1] F. Liu et al, Appl. Phys. Lett. 110, 041607 (2017); https://doi.org/10.1063/1.4974738

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA66

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Received ※ 28 July 2022 — Revised ※ 19 July 2022 — Accepted ※ 07 August 2022 — Issue date ※ 10 August 2022

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WEPA67

Effects of Transverse Dependence of Kicks in Simulations of Microbunched Electron Cooling

hadron, kicker, simulation, proton

780

W.F. Bergan
BNL, Upton, New York, USA
G. Stupakov
SLAC, Menlo Park, California, USA

Funding: This work was supported by Brookhaven Science Associates, LLC under contract No. DE-SC0012704 with the U.S. Department of Energy, and by the Department of Energy, contract DE-AC03-76SF00515.
Microbunched electron cooling (MBEC) is a cooling scheme in which a beam of hadrons to be cooled induces energy perturbations in a beam of electrons. These electron energy perturbations are amplified and turned into density modulations, which in turn provide energy kicks to the hadrons, tending to cool them. For simplification, previous work has modelled the electron-hadron interactions using a disc-disc model, assuming that the inter-particle kicks depend only on the longitudinal distances between individual hadrons and electrons. In reality, these kicks will also have a transverse dependence, which will impact the cooling process. We incorporate this transverse kick dependence into our simulations of the cooling process, allowing us to better understand the physics and provide improved design goals for the MBEC cooler for the Electron-Ion Collider.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA67

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Received ※ 19 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 26 August 2022

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WEPA68

Record Quantum Efficiency from Superlattice Photocathode for Spin Polarized Electron Beam Production

cathode, polarization, lattice, distributed

784

J.P. Biswas, L. Cultrera, K. Kisslinger, W. Liu, J. Skarita, E. Wang
BNL, Upton, New York, USA
S.D. Hawkins, J.F. Klem, S.R. Lee
Sandia National Laboratories, Albuquerque, New Mexico, USA

Funding: The work is supported by Brookhaven Science Associates, LLC under Contract DESC0012704 with the U.S. DOE. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.
Electron sources producing highly spin-polarized electron beams are currently possible only with photocathodes based on GaAs and other III-V semiconductors. GaAs/GaAsP superlattice (SL) photocathodes with a distributed Bragg reflector (DBR) represent the state of the art for the production of spin-polarized electrons. We present results on a SL-DBR GaAs/GaAsP structure designed to leverage strain compensation to achieve simultaneously high QE and spin polarization. These photocathode structures were grown using molecular beam epitaxy and achieved quantum efficiencies exceeding 15% and electron spin polarization of about 75% when illuminated with near bandgap photon energies.

Poster WEPA68 [4.506 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA68

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Received ※ 20 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 10 August 2022

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WEPA69

The Impact on the Vertical Beam Dynamics Due to the Noise in a Horizontal Crab Crossing Scheme

emittance, cavity, feedback, hadron

788

Y. Hao
BNL, Upton, New York, USA
Y. Luo
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA

Funding: Work Supported BY Brookhaven Science Associates, LLC under contract NO. DE-SC0012704 with the U.S. Department of Energy.
Several recent and future colliders have adopted the crab crossing scheme to boost performance. The lower RF control noise of the crab cavities has been identified as one of the significant sources that impact the transverse beam quality in the crabbing plane. However, through beam-beam interaction and other coupling sources, the effect may also affect the non-crabbing plane. In this paper, we report the simulation observations of the beam dynamics in the non-crabbing plane in the presence of phase noise in the crab cavity.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA69

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Received ※ 03 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 06 September 2022

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WEPA75

{6-D} Element-by-Element Particle Tracking with Crab Cavity Phase Noise and Weak-Strong Beam-Beam Interaction for the Hadron Storage Ring of the Electron-Ion Collider

emittance, cavity, simulation, proton

809

Y. Luo, J.S. Berg, M. Blaskiewicz, C. Montag, V. Ptitsyn, F.J. Willeke, D. Xu
BNL, Upton, New York, USA
Y. Hao
FRIB, East Lansing, Michigan, USA
H. Huang
ODU, Norfolk, Virginia, USA
V.S. Morozov
ORNL RAD, Oak Ridge, Tennessee, USA
J. Qiang
LBNL, Berkeley, California, USA
T. Satogata
JLab, Newport News, Virginia, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The Electron Ion Collider (EIC) presently under construction at Brookhaven National Laboratory will collide polarized high energy electron beams with hadron beams with luminosity up to 10³⁴ cm^-2 s^-1 in the center mass energy range of 20 to 140 GeV. Crab cavities are used to compensate the geometric luminosity due to a large crossing angle in the EIC. However, it was found that the phase noise in crab cavities will generate a significant emittance growth for hadron beams and its tolerance from analytical calculation is very small for the Hadron Storage Ring (HSR) of the EIC. In this paper, we report on 6-D symplectic particle tracking to estimate the proton emittance growth rate, especially in the vertical plane, for the HSR with weak-strong beam-beam and other machine or lattice errors.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA75

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Received ※ 01 August 2022 — Revised ※ 06 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 19 August 2022

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WEPA78

Proton-Electron Focusing in EIC Ring Electron Cooler

focusing, proton, emittance, hadron

820

S. Seletskiy, A.V. Fedotov, D. Kayran, J. Kewisch
BNL, Upton, New York, USA

The Electron Ion Collider (EIC) requires a cooling of protons at the top energy. The Ring Electron Cooler (REC) is a suitable option for such a cooling. In this paper we consider an effect of a proton-electron space charge (SC) focusing on the quality of the electron beam in the REC. We show that, with properly adjusted parameters of the Ring Electron Cooler, the SC focusing in the REC cooling section does not significantly affect the cooler performance.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA78

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Received ※ 02 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 20 August 2022

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WEPA81

Time-Resolved Experiments at NSLS II: Motivation and Machine Capabilities

operation, timing, experiment, storage-ring

826

G.M. Wang, B. Bacha, G. Bassi, G.L. Carr, Y. Hidaka, Y. Hu, Y. Li, C. Mazzoli, D. Padrazo Jr, R.S. Rainer, J. Rose, J.T. Sadowski, V.V. Smaluk, Y. Tian, L. Wiegart, G. Williams, X. Yang
BNL, Upton, New York, USA

NSLS-II is a 3-GeV third-generation synchrotron light source at Brookhaven National Lab. The storage ring has been in routine operations for over six years and hosts 28 operating beamlines. The storage ring performance has continuously improved, including 500-mA with limited insertion devices closed, and routine 400-mA top off operation with 90% uniform filling pattern. Recently, we are exploring different operation modes, uniform multi single-bunch mode, and camshaft mode with a high single-bunch charge, to support timing-resolved user experiments. In this paper, we explore the potential for scientific experiments using the pulsed nature of the NSLS, summarize the user requirements on the beam parameters and the progress of accelerator studies.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA81

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Received ※ 04 August 2022 — Revised ※ 12 August 2022 — Accepted ※ 13 August 2022 — Issue date ※ 22 August 2022

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WEPA83

Extended Soft-Gaussian Code for Beam-Beam Simulations

simulation, collider, electromagnetic-fields, proton

830

D. Xu, C. Montag
BNL, Upton, New York, USA
Y. Hao
FRIB, East Lansing, Michigan, USA
Y. Luo
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
J. Qiang
LBNL, Berkeley, California, USA

Large ion beam emittance growth is observed in strong-strong beam-beam simulations for the Electron-Ion Collider (EIC). As we know, the Particle-In-Cell (PIC) solver is subject to numerical noises. As an alternative approach, an extended soft-Gaussian code is developed with help of Hermite polynomials in this paper. The correlation between the horizontal and the vertical coordinates of macro-particles is considered. The 3rd order center moments are also included in the beam-beam force. This code could be used as a cross check tool of PIC based strong-strong simulation.

Poster WEPA83 [0.440 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA83

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Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 24 August 2022

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WEPA85

Localized Beam Induced Heating Analysis of the EIC Vacuum Chamber Components

vacuum, kicker, simulation, injection

833

M.P. Sangroula, D.M. Gassner, C.J. Liaw, C. Liu, P. Thieberger
BNL, Upton, New York, USA
J.R. Bellon, A. Blednykh, C. Hetzel, S. Verdú-Andrés
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy
The Electron-Ion Collider (EIC), to be built at Brookhaven National Laboratory (BNL), is designed to provide a high electron-proton luminosity of 10³⁴ cm^-2 s^-1. One of the challenging tasks for the Electron Storage Ring (ESR) is to operate at an average beam current of 2.5 A within 1160 bunches with a ~ 7 mm bunch length. The Hadron Storage Ring (HSR) will accumulate an average current of 0.69 A within 290 bunches with a 60 mm bunch length. Both rings require the impedance budget simulations. The intense e-beam in the ESR can lead to the overheating of vacuum chamber components due to localized metallic losses. This paper focuses on the beam-induced heating analysis of the ESR vacuum components including bellows, gate-valve, and BPM. To perform thermal analysis, the resistive loss on individual components is calculated with CST and then fed to ANSYS to determine the temperature distribution on the vacuum components. Preliminary results suggest that active water cooling will be required for most of the ESR vacuum components. Similar approach is applied to the HSR vacuum components. The thermal analysis of the HSR stripline injection kicker is presented.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA85

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Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 10 September 2022

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THXD2

6D Phase Space Diagnostics Based on Adaptive Tuning of the Latent Space of Encoder-Decoder Convolutional Neural Networks

controls, solenoid, feedback, network

837

A. Scheinker
LANL, Los Alamos, New Mexico, USA

We present a general approach to 6D phase space diagnostics for charged particle beams based on adaptively tuning the low-dimensional latent space of generative encoder-decoder convolutional neural networks (CNN). Our approach first trains the CNN based on supervised learning to learn the correlations and physics constrains within a given accelerator system. The input of the CNN is a high dimensional collection of 2D phase space projections of the beam at the accelerator entrance together with a vector of accelerator parameters such as magnet and RF settings. The inputs are squeezed down to a low-dimensional latent space from which we generate the output in the form of projections of the beam’s 6D phase space at various accelerator locations. After training the CNN is applied in an unsupervised adaptive manner by comparing a subset of the output predictions to available measurements with the error guiding feedback directly in the low-dimensional latent space. We show that our approach is robust to unseen time-variation of the input beam and accelerator parameters and a study of the robustness of the method to go beyond the span of the training data.

Slides THXD2 [19.086 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THXD2

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Received ※ 18 July 2022 — Revised ※ 05 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 09 August 2022

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THXD6

A Quasi-Optical Beam Position Monitor

coupling, site, photon, cavity

846

S.V. Kuzikov
Euclid TechLabs, Solon, Ohio, USA

There is a strong demand for non-destructive electron Beam Position Monitors (BPMs) for non-perturbative diagnostics of the electron beam position. Challenges are related to the shortness of the electron beam and the noisy chamber environment that are typical for modern RF-driven and plasma-driven accelerators. We propose using a pair of identical high-quality quasi-optical resonators attached to opposite sides of the beam pipe. The resonators can introduce Photonic Band Gap (BPM) structures. These open resonators sustain very low numbers of high-quality modes. We intend to operate at the lowest mode among the others that are capable of being excited by the bunches. The mentioned mode has a coupling coefficient with the beam that depends on the distance between the bunch and the coupling hole. The lower this distance, the higher the coupling. Therefore, comparing the pick-up signals of both resonators with an oscilloscope, we can determine the beam position.

Slides THXD6 [3.745 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THXD6

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Received ※ 25 July 2022 — Accepted ※ 06 August 2022 — Issue date ※ 27 September 2022

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THYD1

XFEL as a Low-Emittance Injector for a 4th-Generation Synchrotron Radiation Source

injection, emittance, storage-ring, synchrotron

850

T. Hara
RIKEN SPring-8 Center, Hyogo, Japan

Low-emittance beam injection is required for the future SPring-8-II due to its small injection beam aperture. To meet this requirement, the SACLA linac has been used as a low-emittance injector since 2020 [1]. In order to perform the beam injection in parallel with XFEL operation, three accelerators are virtually constructed in a control system for the two XFEL beamlines and the beam injection, and thus the accelerator parameters can be independently tuned. Since the reference clock frequencies of the two accelerators are not related by an integer multiple, a new timing system was developed that achieves 3.8 ps (rms) synchronization. To maintain bunch purity better than 1e-8, which is routinely requested at SPring-8, an electron sweeper and an RF knock-out system are introduced for the SACLA injector and the SPring-8 storage ring. Although 0.1 nm-rad emittance of SACLA is increased by an order of magnitude at a transport line mainly due to quantum excitation of synchrotron radiation, it is still small enough for SPring-8-II. By shutting down an old dedicated injector complex, energy consumption has been significantly reduced, and it contributes to create a low-carbon society.
The speaker present this work on behalf of RIKEN-JASRI project team.
[1] Toru Hara et al., Phys. Rev. Accel. Beams 24, 110702 (2021).

Slides THYD1 [10.103 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THYD1

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Received ※ 29 July 2022 — Revised ※ 05 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 23 September 2022

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THYD3

Update on the Status of C-Band Research and Facilities at LANL

cavity, cathode, klystron, operation

855

E.I. Simakov, A.M. Alexander, D.V. Gorelov, T.W. Hall, M.E. Middendorf, D. Rai, T. Tajima, M.R.A. Zuboraj
LANL, Los Alamos, New Mexico, USA

Funding: Los Alamos National Laboratory LDRD Program
We will report on the status of two C-band test facilities at Los Alamos National Laboratory (LANL): C-band Engineering Research Facility in New Mexico (CERF-NM), and Cathodes and Rf Interactions in Extremes (CARIE). Modern applications such as X-ray sources require accelerators with optimized cost of construction and operation, naturally calling for high-gradient acceleration. At LANL we commissioned a high gradient test stand powered by a 50 MW, 5.712 GHz Canon klystron. CERF-NM is the first high gradient C-band test facility in the United States. It was fully commissioned in 2021. In the last year, multiple C-band high gradient cavities and components were tested at CERF-NM. Currently we work to implement several updates to the test stand including the ability to remotedly operate at high gradient for the round-the-clock high gradient conditioning. Adding capability to operate at cryogenic temperatures is considered. The construction of CARIE will begin in October of 2022. CARIE will house a cryo-cooled copper RF photoinjector with a high quantum-efficiency cathode and a high gradient accelerator section.

Slides THYD3 [3.331 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THYD3

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Received ※ 31 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 04 October 2022

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THYD5

Development of Nanopatterned Strong Field Emission Cathodes

cathode, laser, brightness, simulation

863

G.E. Lawler, N. Majernik, J.I. Mann, N. Montanez, J.B. Rosenzweig
UCLA, Los Angeles, California, USA

Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE HEP Grant DE-SC0009914.
Increasing brightness at the cathode is highly desirable for a diverse suite of applications in the electron accelerator community. These applications range from free electron lasers to ultrafast electron diffraction. Many options for higher brightness cathodes are under investigation notably semiconductor cathodes. We consider here the possibility for an alternative paradigm whereby the cathode surface is controlled to reduce the effective area of illumination and emission. We fabricated nanoblade metallic coated cathodes using common nanofabrication techniques. We have demonstrated that a beam can be successfully extracted with a low emittance and we have reconstructed a portion of the energy spectrum. As a result of our particular geometry, our beam possesses a notably high aspect ratio in its transverse plane. We can now begin to consider modifications for the production of intentionally patterned beams such as higher aspect ratios and hollow beams.

Slides THYD5 [4.652 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THYD5

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Received ※ 02 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 05 October 2022

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THYD6

Arrival Time and Energy Jitter Effects on the Performance of X-Ray Free Electron Laser Oscillator

FEL, cavity, laser, radiation

866

G. Tiwari
BNL, Upton, New York, USA
K.-J. Kim, R.R. Lindberg
ANL, Lemont, Illinois, USA
K.-J. Kim
University of Chicago, Chicago, Illinois, USA

Funding: U.S. Dept. of Energy Office of Sciences under Contract No. DE-AC02-06CH11357.
We report on the effects of electron beam arrival time and energy jitter on the power level and the fluctuations of the output of an X-ray FEL oscillator (XFELO). For this study, we apply the FEL driven paraxial resonator model of XFELO along with an analytical reflectivity profile to mimic the phase shift and spectral filtering effects of Bragg-crystals. The thresholds for acceptable timing jitters and energy jitters are determined in terms of the fluctuations of the steady-state power output. We explore potential ways to mitigate the power output fluctuations in the presence of unavoidable electron beam jitters.

Slides THYD6 [1.935 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THYD6

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Received ※ 01 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 03 October 2022

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THYE3

Superconducting Undulators and Cryomodules for X-ray Free-Electron Lasers

FEL, undulator, alignment, quadrupole

870

D.C. Nguyen, G.J. Bouchard, B.M. Dunham, G.L. Gassner, Z. Huang, E.M. Kraft, P. Krejcik, M.A. Montironi, H.-D. Nuhn, T.O. Raubenheimer, Z.R. Wolf, Z. Zhang
SLAC, Menlo Park, California, USA
J.M. Byrd, J.D. Fuerst, E. Gluskin, Y. Ivanyushenkov, M. Kasa, E.R. Moog, M.F. Qian, Y. Shiroyanagi
ANL, Lemont, Illinois, USA

Funding: Work supported by the US DOE Office of Science, Basic Energy Sciences, Office of Accelerator and Detector Research (Manager: Dr. Eliane Lessner).
We present connectable designs of superconducting undulators (SCU) and cryomodules (CM) based on previous SCU and CM designs at Argonne National Lab. The new SCU and CM designs will allow us to connect one CM to the next to form a contiguous line of SCUs with no breaks between the cryomodules. The SCU design will have correctors and phase shifters integrated into the main SCU magnet core, as well as external corrector magnets for trajectory corrections. There will also be a cryogenic magnetic quadrupole and a cold RF beam position monitor (BPM) integrated in the SCU CM. In addition to providing the usual FODO transverse focusing, the quadrupole and BPM will be used for the beam-based alignment technique that is critical for X-ray FEL operation. In this paper, we will present the conceptual design of the new SCU CM as well as results of FEL simulations using the SCUs as afterburners for the LCLS hard X-ray undulators.

Slides THYE3 [2.657 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THYE3

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Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 16 August 2022

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THYE6

First Demonstration of a ZrNb Alloyed Surface for Superconducting Radio-Frequency Cavities

cavity, SRF, radio-frequency, superconductivity

881

Z. Sun, M. Liepe, T.E. Oseroff
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Surface design of the RF surface is a promising path to next-generation SRF cavities. Here, we report a new strategy based on ZrNb surface alloying. Material development via an electrochemical process will be detailed. RF performance evaluated in the Cornell sample host cavity will be discussed. Cornell demonstrates that ZrNb alloying is a viable new technology to improve the performance of SRF cavities.

Slides THYE6 [1.459 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THYE6

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Received ※ 22 July 2022 — Accepted ※ 08 August 2022 — Issue date ※ 20 August 2022

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THZE2

Developing Control System Specifications and Requirements for Electron Ion Collider

controls, instrumentation, operation, software

901

A. Blednykh, D.M. Gassner
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
E.C. Aschenauer, P. Baxevanis, M. Blaskiewicz, K.A. Drees, T. Hayes, J.P. Jamilkowski, G.J. Marr, S. Nemesure, V. Schoefer, T.C. Shrey, K.S. Smith, F.J. Willeke
BNL, Upton, New York, USA
L.R. Dalesio
EPIC Consulting, Medford, New York, USA

An Accelerator Research facility is a unique science and engineering challenge in that the requirements for developing a robust, optimized science facility are limited by engineering and cost limitations. Each facility is planned to achieve some science goal within a given schedule and budget and is then expected to operate for three decades. In three decades, the mechanical systems and the industrial IO to control them is not likely to change. In that same time, electronics will go through some 4 generations of change. The software that integrates the systems and provides tools for operations, automation, data analysis and machine studies will have many new standards. To help understand the process of designing and planning such a facility, we explain the specifications and requirements for the Electron Ion Collider (EIC) from both a physics and engineering perspective.

Slides THZE2 [5.375 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THZE2

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Received ※ 04 August 2022 — Revised ※ 10 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 13 September 2022

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THZE3

An Electrodeless Diamond Beam Monitor

experiment, detector, controls, vacuum

904

S.V. Kuzikov, P.V. Avrakhov, C.-J. Jing, E.W. Knight
Euclid TechLabs, Solon, Ohio, USA
D.S. Doran, C.-J. Jing, J.G. Power, E.E. Wisniewski
ANL, Lemont, Illinois, USA
C.-J. Jing
Euclid Beamlabs, Bolingbrook, USA

Funding: The work was supported by DoE SBIR grant #DE-SC0019642.
Being a wide-band semiconductor, diamond can be used to measure the flux of passing particles based on a particle-induced conductivity effect. We recently demonstrated a diamond electrodeless electron beam halo monitor. That monitor was based on a thin piece of diamond (blade) placed in an open high-quality microwave resonator. The blade partially intercepted the beam. By measuring the change in RF properties of the resonator, one could infer the beam parameters. At Argonne Wakefield Accelerator we have tested 1D and 2D monitors. To enhance the sensitivity of our diamond sensor, we proposed applying a bias voltage to the diamond which can sustain the avalanche of free carriers. In experiment carried out with 120 kV, ~1 µA beam we showed that the response signal for the avalanche monitor biased with up to 5 kV voltage can be up to 100 times larger in comparison with the signal of the same non-biased device.

Slides THZE3 [4.257 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THZE3

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Received ※ 20 July 2022 — Revised ※ 28 July 2022 — Accepted ※ 06 August 2022 — Issue date ※ 08 August 2022

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THZE4

Experimental Characterization of Gas Sheet Transverse Profile Diagnostic

diagnostics, laser, operation, MMI

907

N. Burger, G. Andonian, D.I. Gavryushkin, T.J. Hodgetts, A.-L.M.S. Lamure, M. Ruelas
RadiaBeam, Santa Monica, California, USA
N.M. Cook, A. Diaw
RadiaSoft LLC, Boulder, Colorado, USA
P.E. Denham, P. Musumeci, A. Ody
UCLA, Los Angeles, USA
N.P. Norvell
UCSC, Santa Cruz, California, USA
C.P. Welsch, M. Yadav
The University of Liverpool, Liverpool, United Kingdom
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Transverse profile diagnostics for high-intensity beams require solutions that are non-intercepting and single-shot. In this paper, we describe a gas-sheet ionization diagnostic that employs a precision-shaped, neutral gas jet. As the high-intensity beam passes through the gas sheet, neutral particles are ionized. The ionization products are transported and imaged on a detector. A neural-network based reconstruction algorithm, trained on simulation data, then outputs the initial transverse conditions of the beam prior to ionization. The diagnostic is also adaptable to image the photons from recombination. Preliminary tests at low energy are presented to characterize the working principle of the instrument, including comparisons to existing diagnostics. The results are parametrized as a function of beam charge, spot size, and bunch length.

Slides THZE4 [2.051 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THZE4

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Received ※ 02 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 09 October 2022

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FRXD4

Suppressing the Microbunching Instability at ATF using Laser Assisted Bunch Compression

laser, experiment, simulation, bunching

914

Q.R. Marksteiner, P.M. Anisimov, B.E. Carlsten, G. Latour, E.I. Simakov, H. Xu
LANL, Los Alamos, New Mexico, USA

Funding: This project was supported by funding from the Los Alamos National Laboratory Laboratory Research and Development program.
The microbunching instability in linear accelerators can significantly increase the energy spread of an electron beam. The instability can be suppressed by artificially increasing the random energy spread of an electron beam, but this leads to unacceptably high energy spreads for future XFEL systems. One possibility of suppressing this instability is to use laser assisted bunch compression (LABC) instead of the second chicane in an XFEL system, thereby eliminating the cascaded chicane effect that magnifies the microbunching instability. An experiment is proposed at ATF to test this concept, and numerical simulations of the experiment are shown.

Slides FRXD4 [4.629 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-FRXD4

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Received ※ 03 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 28 September 2022

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FRXD6

Bunch Length Measurements at the CEBAF Injector at 130 kV

laser, simulation, cavity, gun

917

S. Pokharel, G.A. Krafft
ODU, Norfolk, Virginia, USA
M.W. Bruker, J.M. Grames, A.S. Hofler, R. Kazimi, G.A. Krafft, S. Zhang
JLab, Newport News, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
In this work, we investigated the evolution in bunch length of beams through the CEBAF injector for low to high charge per bunch. Using the General Particle Tracer (GPT), we have simulated the beams through the beamline of the CEBAF injector and analyzed the beam to get the bunch lengths at the location of chopper. We performed these simulations with the existing injector using a 130 kV gun voltage. Finally, we describe measurements to validate these simulations. The measurements have been done using chopper scanning technique for two injector laser drive frequency modes: one with 500 MHz, and another with 250 MHz.

Slides FRXD6 [0.800 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-FRXD6

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Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 01 September 2022

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FRXE1

Bayesian Algorithms for Practical Accelerator Control and Adaptive Machine Learning for Time-Varying Systems

network, controls, feedback, experiment

921

A. Scheinker
LANL, Los Alamos, New Mexico, USA
R.J. Roussel
SLAC, Menlo Park, California, USA

Particle accelerators are complicated machines with thousands of coupled time varying components. The electromagnetic fields of accelerator devices such as magnets and RF cavities drift and are uncertain due to external disturbances, vibrations, temperature changes, and hysteresis. Accelerated charged particle beams are complex objects with 6D phase space dynamics governed by collective effects such as space charge forces, coherent synchrotron radiation, and whose initial phase space distributions change in unexpected and difficult to measure ways. This two-part tutorial presents recent developments in Bayesian methods and adaptive machine learning (ML) techniques for accelerators. Part 1: We introduce Bayesian control algorithms, and we describe how these algorithms can be customized to solve practical accelerator specific problems, including online characterization and optimization. Part 2: We give an overview of adaptive ML (AML) combining adaptive model-independent feedback within physics-informed ML architectures to make ML tools robust to time-variation (distribution shift) and to enable their use further beyond the span of the training data without relying on re-training.

Slides FRXE1 [34.283 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-FRXE1

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Received ※ 08 August 2022 — Revised ※ 10 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 27 September 2022

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