NAPAC2022 - List of Keywords (simulation)

Paper	Title	Other Keywords	Page
MOYD3	EIC Transverse Emittance Growth Due to Crab Cavity RF Noise: Estimates and Mitigation	cavity, emittance, feedback, target	6
	T. Mastoridis, P. Fuller, P. Mahvi, Y. Matsumura CalPoly, San Luis Obispo, California, USA
	Funding: This work is partially supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Award Number DE-SC-0019287. The Electron-Ion Collider (EIC) requires crab cavities to compensate for a 25 mrad crossing angle and achieve maximum luminosity. The crab cavity Radio Frequency (RF) system will inject low levels of noise to the crabbing field, generating transverse emittance growth and potentially limiting luminosity lifetime. In this work, we estimate the transverse emittance growth rate as a function of the Crab Cavity RF noise and quantify RF noise specifications for reasonable performance. Finally, we evaluate the possible mitigation of the RF noise induced emittance growth via a dedicated feedback system.
	Slides MOYD3 [0.223 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYD3
About •	Received ※ 28 July 2022 — Revised ※ 01 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 04 October 2022
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MOYD4	Model Parameters Determination in EIC Strong-Strong Simulation	electron, 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, electron, 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	electron, experiment, 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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MOZE3	Emittance Measurements and Simulations from an X-Band Short-Pulse Ultra-High Gradient Photoinjector	emittance, gun, linac, laser	45
	G. Chen, D.S. Doran, C.-J. Jing, S.Y. Kim, W. Liu, W. Liu, P. Piot, J.G. Power, C. Whiteford, E.E. Wisniewski ANL, Lemont, Illinois, USA C.-J. Jing, E.W. Knight, S.V. Kuzikov Euclid TechLabs, Solon, Ohio, USA C.-J. Jing Euclid Beamlabs, Bolingbrook, USA X. Lu, P. Piot, W.H. Tan Northern Illinois University, DeKalb, Illinois, USA
	Funding: This work is supported by the U.S. DOE, under award No. DE-SC0018656 to NIU, DOE SBIR grant No. DE-SC0018709 to Euclid Techlabs LLC, and contract No. DE-AC02-06CH11357 with ANL. A program is under way at the Argonne Wakefield Accelerator facility, in collaboration with the Euclid Techlabs and Northern Illinois University (NIU), to develop a GeV/m scale photocathode gun, with the ultimate goal of demonstrating a high-brightness photoinjector beamline. The novel X-band photoemission gun (Xgun) is powered by high-power, short RF pulses, 9-ns (FWHM), which, in turn, are generated by the AWA drive beam. In a previous proof-of-principle experiment, an unprecedented 400~MV/m gradient on the photocathode surface* was demonstrated. In the current version of the experiment, we added a linac to the beamline to increase the total energy and gain experience tuning the beamline. In this paper, we report on the very first result of emittance measurement as well as several other beam parameters. This preliminary investigation has identified several factors to be improved on in order to achieve one of the ultimate goals; low emittance. * W. H. Tan et al., "Demonstration of sub-GV/m Accelerating Field in a Photoemission Electron Gun Powered by Nanosecond X-Band Radiofrequency Pulses", 2022. arXiv:2203.11598v1
	Slides MOZE3 [5.565 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZE3
About •	Received ※ 03 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 14 August 2022
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MOZE4	Ceramic Enhanced Accelerator Structure Low Power Test and Designs of High Power and Beam Tests	cavity, electron, impedance, accelerating-gradient	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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MOZE5	Simulation and Experimental Results of Dielectric Disk Accelerating Structures	accelerating-gradient, experiment, wakefield, impedance	52
	S. Weatherly, E.E. Wisniewski Illinois Institute of Technology, Chicago, Illinois, USA D.S. Doran, C.-J. Jing, J.F. Power, E.E. Wisniewski ANL, Lemont, Illinois, USA B.T. Freemire, C.-J. Jing Euclid Beamlabs, Bolingbrook, USA
	Funding: Contract DE-SC0019864 to Euclid Beamlabs LLC. AWA work from U.S. DOE Office of Science under Contract DE-AC02-06CH11357. Chicagoland Accelerator Science Traineeship U.S. DOE award number DE-SC-0020379 A method of decreasing the required footprint of linear accelerators and improving their energy efficiency is to employ Dielectric Disk Accelerators (DDAs) with short RF pulses ( ∼ 9 ns). A DDA is an accelerating structure that utilizes dielectric disks to improve the shunt impedance. Two DDA structures have been designed and tested at the Argonne Wakefield Accelerator. A single cell clamped DDA structure recently achieved an accelerating gradient of 1{02} MV/m. A multi-cell clamped DDA structure has been designed and is being fabricated. Simulation results for this new structure show a 1{08} MV/m accelerating gradient with 400 MW of input power with a high shunt impedance and group velocity. The engineering design has been improved from the single cell structure to ensure consistent clamping over the entire structure.
	Slides MOZE5 [9.338 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZE5
About •	Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 21 August 2022 — Issue date ※ 06 October 2022
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MOPA01	Realistic CAD-Based Geometries for Arbitrary Magnets with Beam Delivery Simulation (BDSIM)	vacuum, extraction, synchrotron, proton	55
	E. Ramoisiaux, R. Dantinne, E. Gnacadja, C. Hernalsteens, S. Musibau, B. Ndihokubwayo, N. Pauly, R. Tesse, M. Vanwelde ULB, Bruxelles, Belgium S.T. Boogert, L.J. Nevay, W. Shields Royal Holloway, University of London, Surrey, United Kingdom C. Hernalsteens CERN, Meyrin, Switzerland
	Monte Carlo simulations are required to evaluate beam losses and secondary radiation accurately in particle accelerators and beamlines. Detailed CAD geometries are critical to account for a realistic distribution of material masses but increase the model complexity and often lead to code duplication. Beam Delivery Simulation (BDSIM) and the Python package pyg4ometry enable handling such accelerator models within a single, simplified workflow to run complete simulations of primary and secondary particle tracking and interactions with matter using Geant4 routines. Additional capabilities have been developed to model arbitrary bent magnets by associating externally modeled geometries to the magnet poles, yoke, and beampipe. Individual field descriptions can be associated with the yoke and vacuum pipe separately to provide fine-grained control of the magnet model. The implementation of these new features is described in detail and applied to the modeling of the CERN Proton Synchrotron (PS) combined function magnets.
	Poster MOPA01 [0.781 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA01
About •	Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 16 September 2022
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MOPA02	Activation of the IBA Proteus One Proton Therapy Beamline Using BDSIM and FISPACT-II	proton, neutron, shielding, radiation	59
	E. Ramoisiaux, E. Gnacadja, C. Hernalsteens, N. Pauly, R. Tesse, M. Vanwelde ULB, Bruxelles, Belgium C. Hernalsteens CERN, Meyrin, Switzerland
	Cyclotron-based proton therapy systems generate large fluxes of secondary particles due to the beam interactions with the beamline elements, with the energy degrader being the dominant source. Compact systems exacerbate these challenges for concrete shielding and beamline element activation. Our implementation of the Rigorous Two-Step method uses Beam Delivery Simulation (BDSIM), a Geant4-based particle tracking code, for primary and secondary particles transport and fluence scoring, and FISPACT-II for time-dependent nuclear inventory and solving the rate equations. This approach is applied to the Ion Beam Applications (IBA) Proteus®ONE (P1) system, for which a complete model has been built, validated, and used for shielding activation simulations. We detail the first simulations of the activation on quadrupole magnets in high-fluence locations downstream of the degrader. Results show the evolution of the long-lived nuclide concentrations for short and long timescales throughout the facility lifetime for a typical operation scenario.
	Poster MOPA02 [0.553 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA02
About •	Received ※ 02 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 19 August 2022 — Issue date ※ 21 September 2022
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MOPA09	Design of a 4D Emittance Diagnostic for Low-Energy Ion Beams	diagnostics, emittance, quadrupole, linac	67
	T.R. Curtin, M.S. Curtin Ion Linac Systems, Inc., Albuquerque, USA
	Characterization of ion beams from an ion injector consisting of an electron-cyclotron-resonance (ECR) source in combination with a low-energy-beam-transport (LEBT) typically exhibits a complex four-dimensional transverse phase-space distribution. The importance of measuring the ion beam correlations following extraction and transport of the low-energy beam is critical to enabling optimization of beam transmission through downstream accelerating structures. A design for a transverse, four-dimensional emittance meter for low-energy protons from the Ion Linac Systems (ILS) ECR-LEBT ion injector is provided.
	Poster MOPA09 [0.479 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA09
About •	Received ※ 03 August 2022 — Revised ※ 27 September 2022 — Accepted ※ 05 December 2022 — Issue date ※ 05 December 2022
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MOPA13	Design of a Surrogate Model for MUED at BNL Using VSim, Elegant and HPC	gun, electron, 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)	electron, solenoid, optics, 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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MOPA29	Second Generation Fermilab Main Injector 8 GeV Beamline Collimation Preliminary Design	collimation, vacuum, shielding, controls	116
	K.J. Hazelwood, P. Adamson, B.C. Brown, D. Capista, R.M. Donahue, B.L. Klein, N.V. Mokhov, V.S. Pronskikh, V.I. Sidorov, M.C. Vincent Fermilab, Batavia, Illinois, USA
	The current Fermilab Main Injector 8 GeV beamline transverse collimation system was installed in 2006. Since then, proton beam intensities and rates have increased significantly. With the promise of even greater beam intensities and a faster repetition rate when the PIP-II upgrade completes later this decade, the current collimation system will be insufficient. Over the past 18 months, multiple collimation designs have been investigated, some more traditional and others novel. A preliminary design review was conducted and a design chosen. Work is underway to finalize the chosen design, prototype some of its novel components and procure parts for installation Summer 2023.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA29
About •	Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 15 August 2022 — Issue date ※ 25 September 2022
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MOPA46	Cryogenic Dielectric Structure with GΩ/m Level Shunt Impedance	impedance, cryogenics, acceleration, accelerating-gradient	157
	R.A. Kostin, C. Jing Euclid Beamlabs, Bolingbrook, USA
	Shunt impedance is one of the most important parameters characterizing particle acceleration efficiency. It is known that RF losses are reduced at cryogenic temperatures. For example, a record high shunt impedance of 350 MΩ/m was demonstrated recently for all metal X-band accelerating structure, which is more than 2 times higher than that at room temperature. In this article we present a novel hybrid dielectric structure which can achieve even higher shunt impedance due to the fact that losses in dielectric materials reduced much more than in pure copper.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA46
About •	Received ※ 12 August 2022 — Revised ※ 16 August 2022 — Accepted ※ 23 August 2022 — Issue date ※ 17 September 2022
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MOPA50	Integrated Photonics Structure Cathodes for Longitudinally Shaped Bunch Trains	wakefield, cathode, emittance, laser	160
	S.J. Coleman, D.T. Abell, C.C. Hall RadiaSoft LLC, Boulder, Colorado, USA R. Kapadia University of Southern California, Los Angeles, California, USA S.S. Karkare Arizona State University, Tempe, USA S.Y. Kim, P. Piot, J.F. Power ANL, Lemont, Illinois, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DOE DE-SC0021681 Compact, high-gradient structure wakefield accelerators can operate at improved efficiency using shaped electron beams, such as a high transformer ratio beam shape, to drive the wakes. These shapes have generally come from a photocathode gun followed by a transverse mask to imprint a desired shape on the transverse distribution, and then an emittance exchanger (EEX) to convert that transverse shape into a longitudinal distribution. This process discards some large fraction of the beam, limiting wall-plug efficiency as well as leaving a solid object in the path of the beam. In this paper, we present a proposed method of using integrated photonics structures to control the emission pattern on the cathode surface. This transverse pattern is then converted into a longitudinal pattern at the end of an EEX. This removes the need for the mask, preserving the total charge produced at the cathode surface. We present simulations of an experimental set-up to demonstrate this concept at the Argonne Wakefield Accelerator.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA50
About •	Received ※ 03 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 26 August 2022 — Issue date ※ 03 October 2022
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MOPA55	Facilitating Machine Learning Collaborations Between Labs, Universities, and Industry	controls, software, operation, framework	164
	J.P. Edelen, D.T. Abell, D.L. Bruhwiler, S.J. Coleman, N.M. Cook, A. Diaw, J.A. Einstein-Curtis, C.C. Hall, M.C. Kilpatrick, B. Nash, I.V. Pogorelov RadiaSoft LLC, Boulder, Colorado, USA K.A. Brown BNL, Upton, New York, USA S. Calder ORNL RAD, Oak Ridge, Tennessee, USA A.L. Edelen, B.D. O’Shea, R.J. Roussel SLAC, Menlo Park, California, USA C.M. Hoffmann ORNL, Oak Ridge, Tennessee, USA E.-C. Huang LANL, Los Alamos, New Mexico, USA P. Piot Northern Illinois University, DeKalb, Illinois, USA C. Tennant JLab, Newport News, Virginia, USA
	It is clear from numerous recent community reports, papers, and proposals that machine learning is of tremendous interest for particle accelerator applications. The quickly evolving landscape continues to grow in both the breadth and depth of applications including physics modeling, anomaly detection, controls, diagnostics, and analysis. Consequently, laboratories, universities, and companies across the globe have established dedicated machine learning (ML) and data-science efforts aiming to make use of these new state-of-the-art tools. The current funding environment in the U.S. is structured in a way that supports specific application spaces rather than larger collaboration on community software. Here, we discuss the existing collaboration bottlenecks and how a shift in the funding environment, and how we develop collaborative tools, can help fuel the next wave of ML advancements for particle accelerators.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA55
About •	Received ※ 10 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 22 August 2022 — Issue date ※ 01 September 2022
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MOPA59	Prediction of Gaseous Breakdown for Plasma Cleaning of RF Cavities	cavity, plasma, electron, 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, electron, 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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MOPA63	Multiphysics Simulation of the Thermal Response of a Nanofibrous Target in a High-Intensity Beam	target, experiment, radiation, proton	185
	W.J. Asztalos IIT, Chicago, Illinois, USA S.K. Bidhar, F. Pellemoine Fermilab, Batavia, Illinois, USA P. Rath IIT Bhubaneswar, Jatni, India Y. Torun Illinois Institute of Technology, Chicago, Illlinois, USA
	Nanofibrous structures are of high interest to the fields of engineering and materials science, and investigation of their properties as well as discovery of novel applications for them both constitute lively areas of research. A very promising application of nanofiber mats lies in the field of accelerator technology: beam targets made from nanofiber mats offer a solution to the problem of advancing the "intensity frontier"–-the limit on the beam intensities that can be realized in fixed target experiments and neutrino production facilities. However, testing has shown that the survivability of these nanofiber targets depends strongly on their manufacturing parameters, such as the packing density of fibers. In this work, we will use multiphysics simulations to perform a thermal study on how nanofiber targets react to high intensity beams, so that the dependency of the targets’ lifetime on their construction parameters can be better understood.
	Poster MOPA63 [3.656 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA63
About •	Received ※ 14 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 04 August 2022 — Issue date ※ 25 August 2022
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MOPA72	Preliminary Tests and Beam Dynamics Simulations of a Straight-Merger Beamline	dipole, experiment, cavity, electron	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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MOPA76	Wakefield Modeling in Sub-THz Dielectric-Lined Waveguides	wakefield, electron, 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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MOPA79	Studying the Emission Characteristics of Field Emission Cathodes with Various Geometries	cathode, emittance, experiment, ECR	226
	M.R. Howard, S.M. Lidia FRIB, East Lansing, Michigan, USA J.E. Coleman LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the NNSA of US DOE under contract 89233218CNA000001 and partially supported by the US DOE under Cooperative Agreement award number DE-SC0018362 and Michigan State University. The cathode test stand (CTS) at LANL is designed to hold off voltages of up to 500kV and can supply pulse durations up to 2.6 μs. Using this test stand, we are able to test both field emission and photocathodes with different geometries and materials at various pulse lengths and PFN voltages. Currently, the test stand is used to evaluate field emission using a velvet cathode over various pulse lengths. The CTS employs various diagnostic tools, including E-dots, B-dots, and a scintillator coupled with a pepperpot mask in order to measure the extracted voltage, current, beam distribution, and transverse emittance. Xenos [1] has been used to create and simulate diode geometries that permits study to optimize various beam parameters. These geometries include changing the size and recess of the cathode as well as implementing a Pierce geometry. Here, we will discuss comparisons for various simulated cathodes and how changes in geometry impact given beam parameters. [1] See https://www.fieldp.com/xenos.html for information about the Xenos software.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA79
About •	Received ※ 02 August 2022 — Revised ※ 10 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 30 August 2022
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MOPA80	Design Study for Non-Intercepting Gas-Sheet Profile Monitor at FRIB	photon, heavy-ion, detector, electron	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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MOPA90	Relating Initial Distribution to Beam Loss on the Front End of a Heavy-Ion Linac Using Machine Learning	network, LEBT, emittance, controls	263
	A.D. Tran, Y. Hao FRIB, East Lansing, Michigan, USA J.L. Martinez Marin, B. Mustapha ANL, Lemont, Illinois, USA
	Funding: This work was supported by a sub-reward from Argonne National Laboratory and supported by the U.S. Department of Energy, under Contract No. DE-AC02-06CH11357. This work demonstrates using a Neural Network and a Gaussian Process to model the ATLAS front-end. Various neural network architectures were created and trained on the machine settings and outputs to model the phase space projections. The model was then trained on a dataset, with non-linear distortion, to gauge the transferability of the model from simulation to machine.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA90
About •	Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 11 September 2022
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TUXD6	Dual Radiofrequency Cavity Based Monochromatization for High Resolution Electron Energy Loss Spectroscopy	cavity, electron, cathode, 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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TUYE2	Next Generation Computational Tools for the Modeling and Design of Particle Accelerators at Exascale	GPU, software, space-charge, plasma	302
	A. Huebl, R. Lehé, C.E. Mitchell, J. Qiang, R.D. Ryne, R.T. Sandberg, J.-L. Vay LBNL, Berkeley, USA
	Funding: Work supported by the Exascale Computing Project (17-SC-20-SC), a collaborative effort of the U.S. DOE SC and the NNSA, resources of NERSC, and by LBNL LDRD under DOE Contract DE-AC02-05CH11231. Particle accelerators are among the largest, most complex devices. To meet the challenges of increasing energy, intensity, accuracy, compactness, complexity and efficiency, increasingly sophisticated computational tools are required for their design and optimization. It is key that contemporary software take advantage of the latest advances in computer hardware and scientific software engineering practices, delivering speed, reproducibility and feature composability for the aforementioned challenges. A new open source software stack is being developed at the heart of the Beam pLasma Accelerator Simulation Toolkit (BLAST) by LBNL and collaborators, providing new particle-in-cell modeling codes capable of exploiting the power of GPUs on Exascale supercomputers. Combined with advanced numerical techniques, such as mesh-refinement, and intrinsic support for machine learning, these codes are primed to provide ultrafast to ultraprecise modeling for future accelerator design and operations. [1] J.-L. Vay, A. Huebl, et al, Phys. Plasmas 28, 023105 (2021) [2] J.-L. Vay, A. Huebl, et al, J. Instr. 16, T10003 (2021) [3] A. Myers, et al (incl. A. Huebl), Parallel Comput. 108, 102833 (2021)
	Slides TUYE2 [9.399 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYE2
About •	Received ※ 13 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 11 August 2022
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TUZE3	Optimizing the Discovery of Underlying Nonlinear Beam Dynamics	lattice, MMI, linear-dynamics, experiment	335
	L.A. Pocher, T.M. Antonsen, L. Dovlatyan, I. Haber, P.G. O’Shea UMD, College Park, Maryland, USA
	Funding: Work supported by US DOE-HEP grants: DE-SC0010301 and DE-SC0022009 One of the DOE-HEP Grand Challenges identified by Nagaitsev et al. relates to the use of virtual particle accelerators for beam prediction and optimization. Useful virtual accelerators rely on efficient and effective methodologies grounded in theory, simulation, and experiment. This paper uses an algorithm called Sparse Identification of Nonlinear Dynamical systems (SINDy), which has not previously been applied to beam physics. We believe the SINDy methodology promises to simplify the optimization of accelerator design and commissioning, particularly where space charge is important. We show how SINDy can be used to discover and identify the underlying differential equation system governing the beam moment evolution. We compare discovered differential equations to theoretical predictions and results from the PIC code WARP modeling. We then integrate the discovered differential system forward in time and compare the results to data analyzed in prior work using a Machine Learning paradigm called Reservoir Computing. Finally, we propose extending our methodology, SINDy for Virtual Accelerators (SINDyVA), to the broader community’s computational and real experiments.
	Slides TUZE3 [3.141 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZE3
About •	Received ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 22 August 2022
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TUZE4	Particle-in-Cell Simulations of High Current Density Electron Beams in the Scorpius Linear Induction Accelerator	electron, 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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TUZE6	Studies of Ion Instability Using a Gas Injection System	feedback, emittance, injection, experiment	347
	J.R. Calvey, M. Borland, L. Emery, P.S. Kallakuri ANL, Lemont, Illinois, USA
	Funding: Work supported by U. S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. Ion trapping occurs when a negatively charged beam ionizes residual gas inside an accelerator vacuum chamber, and the resulting ions become trapped in the beam potential. Trapped ions can cause a variety of undesirable effects, including coherent instability and incoherent emittance growth. Because of the challenging emittance and stability requirements of next generation light sources, ion trapping is a serious concern. To study this effect at the present APS, a gas injection system was designed and installed at two different locations in the ring. The system creates a controlled and localized pressure bump of nitrogen gas, so the resulting ion instability can be studied. Measurements were taken under a wide variety of beam conditions, using a spectrum analyzer, pinhole camera, and bunch-by-bunch feedback system. The feedback system was also used to perform grow-damp measurements, allowing us to measure the growth rate of individual unstable modes. This paper will present some of the results of these experiments. Simulations using the IONEFFECTS element in the particle tracking code elegant will also be presented.
	Slides TUZE6 [2.425 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZE6
About •	Received ※ 03 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 24 August 2022
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TUPA04	Sheet Electron Probe for Beam Tomography	electron, proton, diagnostics, cathode	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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TUPA16	Singularity-Free Exact Dipole Bend Transport Equations	dipole, lattice, GUI, framework	375
	D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Department of Energy Exact transport equations for a pure dipole bend (a bend with a dipole field and nothing else) have been derived and formulated to avoid singularities when evaluated. The transport equations include finite edge angles and no assumption is made in terms of the bending field being matched to the curvature of the coordinate system.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA16
About •	Received ※ 05 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 16 September 2022
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TUPA18	Promise and Challenges of a Method for 5x5 Sigma Matrix Measurement in a Transport Line	quadrupole, booster, extraction, emittance	382
	M. Borland, V. Sajaev, K.P. Wootton ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source (APS) is upgrading the storage ring to a design that requires on-axis injection. Matching between the incoming beam and the ring is important to ensure high injection efficiency. Toward this end, we have developed and tested a method for measuring all σ matrix elements except those related to the time coordinate. We report on challenges inherent in this technique, based on simulation and real-world trials.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA18
About •	Received ※ 29 July 2022 — Accepted ※ 05 August 2022 — Issue date ※ 29 September 2022
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TUPA19	Avoiding Combinatorial Explosion in Simulation of Multiple Magnet Errors in Swap-Out Safety Tracking for the Advanced Photon Source Upgrade	photon, lattice, injection, storage-ring	386
	M. Borland, R. Soliday ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source (APS) is upgrading the storage ring to a hybrid seven-bend-achromat design with reverse bends, providing a natural emittance of 41 pm at 6 GeV. The small dynamic acceptance entails operation in on-axis swap-out mode. Careful consideration is required of the safety implications of injection with shutters open. Tracking studies require simulation of multiple simultaneous magnet errors, some combinations of which may introduce potentially dangerous conditions. A naive grid scan of possible errors, while potentially very complete, would be prohibitively time-consuming. We describe a different approach using biased sampling of particle distributions from successive scans. We also describe other aspects of the simulations, such as use of 3D field maps and a highly detailed aperture model.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA19
About •	Received ※ 01 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 10 September 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	electron, 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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TUPA27	Longitudinal Feedback Dynamics in Storage Rings with Small Synchrotron Tunes	feedback, HOM, synchrotron, cavity	405
	R.R. Lindberg ANL, Lemont, Illinois, USA
	Funding: This work was supported by U.S. Dept. of Energy Office of Sciences under Contract No. DE-AC02-06CH11357. We analyze the dynamics of multibunch longitudinal instabilities including bunch-by-bunch feedback under the assumption that the synchrotron tune is small. We find that increasing the feedback response does not always guarantee stability, even in the ideal case with no noise. As an example, we show that if the growth rate of a cavity-driven mode is of the order of the synchrotron frequency, then there are parameter regions for which the instability cannot be controlled by feedback irrespective of its gain. We verify these calculations with tracking simulations relevant to the APS-U, and find that the dynamics do not depend upon whether the longitudinal feedback relies on phase-sensing or energy-sensing technology. Hence, this choice should be dictated by measurement accuracy and noise considerations.
	Poster TUPA27 [1.180 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA27
About •	Received ※ 26 July 2022 — Revised ※ 05 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 26 August 2022
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TUPA28	Update on the Development of a Low-Cost Button BPM Signal Detector at AWA	pick-up, detector, electron, 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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TUPA30	Development of a Compact 2D Carbon Beam Scanner for Cancer Therapy	proton, power-supply, magnet-design, radiation	417
	B. Mustapha, A. Barcikowski, J.A. Nolen ANL, Lemont, Illinois, USA V.P. Derenchuk, P. Osucha ProNova Solutions, Knoxville, USA N. Tsoupas BNL, Upton, New York, USA
	Funding: This work was supported by the U.S. Department of Energy, under Contract No. DE-AC02-06CH11357. This research was support through the DOE’s Accelerator Stewardship program. A novel trapezoidal coil 2D carbon beam scanner has been designed, and a prototype has been successfully developed and tested. The field performance of the magnet has been characterized and it is in excellent agreement with the simulations. A better than 1% field uniformity in both planes has been achieved within the useful aperture of the magnet. This represents a significant improvement over the prior art of the elephant-ear scanner design. A comparison of the two designs and the results from the new trapezoidal-coil design will be presented and discussed. Higher power and online beam testing are planned in the near future.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA30
About •	Received ※ 25 July 2022 — Revised ※ 14 August 2022 — Accepted ※ 15 August 2022 — Issue date ※ 25 August 2022
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TUPA32	SCU Ends Configured as Phase Shifter	undulator, FEL, electron, 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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TUPA34	Model-Based Calibration of Control Parameters at the Argonne Wakefield Accelerator	network, controls, gun, wakefield	427
	I.P. Sugrue, B. Mustapha, P. Piot, J.G. Power ANL, Lemont, Illinois, USA N. Krislock Northern Illinois University, DeKalb, Illinois, USA
	Particle accelerators utilize a large number of control parameters to generate and manipulate beams. Digital models and simulations are often used to find the best operating parameters to achieve a set of given beam parameters. Unfortunately, the optimized physics parameters cannot precisely be set in the control system due to, e.g., calibration uncertainties. We developed a data-driven physics-informed surrogate model using neural networks to replace digital models relying on beam-dynamics simulations. This surrogate model can then be used to perform quick diagnostics of the Argonne Wakefield accelerator in real time using nonlinear least-squares methods to find the most likely operating parameters given a measured beam distribution.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA34
About •	Received ※ 05 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 24 September 2022
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TUPA42	LANSCE Modernization Project at LANL	rfq, experiment, proton, LEBT	443
	D.V. Gorelov, J. Barraza, D.A.D. Dimitrov, I. Draganić, E. Henestroza, S.S. Kurennoy LANL, Los Alamos, New Mexico, USA
	In the framework of LANSCE Accelerator Modernization Project preliminary research, during evaluation of critical technology elements it was found that the proposed RFQ design had not yet been demonstrated experimentally worldwide. Such an RFQ should combine the ability of traditional light ion RFQs (i.e., [1]) and the flexibility of acceleration of pre-bunched beams, like RFQs for heavy ions [2]. The proposed RFQ should be able to accelerate H⁺ and H⁻ beams with 35-mA beam current from 100 keV to 3 MeV and at the same time preserve the prescribed macro-bunch beam time structure required by experiments. New algorithms for RFQ geometry generation have been proposed, and optimization algorithms are being developed at LANL. LAMP demonstration plans also include development of a new set of electrodes for the existing RFQ at our Test Stand that will allow us to demonstrate the critical technology ahead of time in a laboratory experimental setup with low duty factor and low energy. [1] S. Henderson et al., Nucl. Instrum. Methods Phys. Res., Sect. A, v. 763, pp. 610-673 (2014). [2] H. Ren et al., J. Phys. Conf. Ser., v. 1067, 052010 (2018).
	Poster TUPA42 [0.635 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA42
About •	Received ※ 04 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 18 August 2022
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TUPA48	Effect of Lattice Misalignments on Beam Dynamics in LANSCE Linear Accelerator	alignment, emittance, linac, lattice	455
	Y.K. Batygin, S.S. Kurennoy LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by US DOE under contract 89233218CNA000001 Accelerator channel misalignments can significantly affect beam parameters in long linear accelerators. Measurements of misalignments of the LANSCE linac lattice elements was performed by the Mechanical Design Engineering Group of the Los Alamos Accelerator Operations and Technology Division. In order to determine effect of misalignment on beam parameters in LANSCE linac, the start-to-end simulations of LANSCE accelerator were performed using Beampath and CST codes including measured displacements of quadrupoles and accelerating tanks. Simulations were done for both H⁺ and H⁻ beams with various beam flavors. Effect of misalignments was compared with those due to beam space charge and distortion of RF field along the channel. Paper presents results of simulation and comparison with experimental data of beam emittance growth along the machine.
	Poster TUPA48 [1.547 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA48
About •	Received ※ 23 July 2022 — Revised ※ 28 July 2022 — Accepted ※ 04 August 2022 — Issue date ※ 14 August 2022
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TUPA53	Modeling of Nonlinear Beam Dynamics via a Novel Particle-Mesh Method and Surrogate Models with Symplectic Neural Networks	network, electron, 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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TUPA57	Electromagnetic and Beam Dynamics Modeling of the LANSCE Coupled-Cavity Linac	cavity, linac, emittance, quadrupole	472
	S.S. Kurennoy, Y.K. Batygin, D.V. Gorelov LANL, Los Alamos, New Mexico, USA
	The 800-MeV proton linac at LANSCE consists of a drift-tube linac, which brings the beam to 100 MeV, followed by a coupled-cavity linac (CCL) consisting of 44 modules. Each CCL module contains multiple tanks, and it is fed by a single 805-MHz klystron. CCL tanks are multi-cell blocks of identical re-entrant side-coupled cavities, which are followed by drifts with magnetic quadrupole doublets. Bridge couplers - special cavities displaced from the beam axis - electromagnetically couple CCL tanks over such drifts. We have developed 3D CST models of CCL tanks. Their electromagnetic analysis is performed using MicroWave Studio. Beam dynamics is modeled with Particle Studio for bunch trains with realistic beam distributions using the CST calculated RF fields and quadrupole magnetic fields to determine the output beam parameters. Beam dynamics results are crosschecked with other multi-particle codes.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA57
About •	Received ※ 15 July 2022 — Revised ※ 01 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 19 August 2022
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TUPA73	Design and Low Power Test of an Electron Bunching Enhancer Using Electrostatic Potential Depression	cavity, electron, 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	electron, plasma, radiation, 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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TUPA80	Cyborg Beamline Development Updates	gun, cathode, cavity, cryogenics	512
	G.E. Lawler, A. Fukasawa, N. Majernik, J.R. Parsons, J.B. Rosenzweig, Y. Sakai UCLA, Los Angeles, California, USA F. Bosco Sapienza University of Rome, Rome, Italy Z. Li, S.G. Tantawi SLAC, Menlo Park, California, USA B. Spataro LNF-INFN, Frascati, Italy
	Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE Contract DE-SC0020409. Xray free electron laser (XFEL) facilities in their current form are large, costly to maintain, and inaccessible due to their minimal supply and high demand. It is then advantageous to consider miniaturizing XFELs through a variety of means. We hope to increase beam brightness from the photoinjector via high gradient operation (>120 MV/m) and cryogenic temperature operation at the cathode (<77K). To this end we have designed and fabricated our new CrYogenic Brightness-Optimized Radiofrequency Gun (CYBGORG). The photogun is 0.5 cell so much less complicated than our eventual 1.6 cell photoinjector. It will serve as a prototype and test bed for cathode studies in a new cryogenic and very high gradient regime. We present here the fabricated structure, progress towards commissioning, and beamline simulations.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA80
About •	Received ※ 02 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 09 October 2022
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TUPA82	Transverse Stability in an Alternating Symmetry Planar Dielectric Wakefield Structure	wakefield, experiment, accelerating-gradient, quadrupole	519
	W.J. Lynn, G. Andonian, N. Majernik, S.M. OTool, J.B. Rosenzweig UCLA, Los Angeles, California, USA D.S. Doran, S.Y. Kim, J.F. Power, E.E. Wisniewski ANL, Lemont, Illinois, USA P. Piot Northern Illinois University, DeKalb, Illinois, USA
	Funding: DE-SC0017648 - AWA. Dielectric Wakefield Acceleration (DWA) is a promising technique for realizing the next generation of linear colliders. It provides access to significantly higher accelerating gradients than traditional radio-frequency cavities. One impediment to realizing a DWA-powered accelerator is the issue of the transverse stability of the beams within the dielectric structure due to short-range wakefields. These short-range wakefields have a tendency to induce a phenomenon known as single-bunch beam breakup, which acts as its name implies and destroys the relevant beam. We attempt to solve this issue by leveraging the quadrupole mode excited in a planar dielectric structure and then alternating the orientation of said structure to turn an unstable system into a stable one. We examine this issue computationally to determine the limits of stability and based on those simulations describe a future experimental realization of this strategy.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA82
About •	Received ※ 02 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 30 September 2022
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TUPA83	Derivative-Free Optimization of Multipole Fits to Experimental Wakefield Data	wakefield, multipole, experiment, electron	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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TUPA84	Reconstructing Beam Parameters from Betatron Radiation Through Machine Learning and Maximum Likelihood Estimation	radiation, betatron, diagnostics, plasma	527
	S. Zhang, N. Majernik, B. Naranjo, J.B. Rosenzweig, M. Yadav UCLA, Los Angeles, California, USA Ö. Apsimon, C.P. Welsch, M. Yadav The University of Liverpool, Liverpool, United Kingdom
	Funding: US Department of Energy, Division of High Energy Physics, under Contract No. DE-SC0009914. The dense drive beam used in plasma wakefield acceleration generates a linear focusing force that causes electrons inside the witness beam to undergo betatron oscillations, giving rise to betatron radiation. Because information about the properties of the beam is encoded in the betatron radiation, measurements of the radiation such as those recorded by the UCLA-built Compton spectrometer can be used to reconstruct beam parameters. Two possible methods of extracting information about beam parameters from measurements of radiation are machine learning (ML), which is increasingly being implemented for different fields of beam diagnostics, and a statistical technique known as maximum likelihood estimation (MLE). We assess the ability of both machine learning and MLE methods to accurately extract beam parameters from measurements of betatron radiation.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA84
About •	Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 05 October 2022
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TUPA87	Simulations for the Space Plasma Experiments at the SAMURAI Lab	electron, plasma, 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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WEXD5	Benchmarking Simulation for AWA Drive Linac and Emittance Exchange Beamline Using OPAL, GPT, and Impact-T	emittance, linac, gun, solenoid	552
	S.Y. Kim, G. Chen, D.S. Doran, G. Ha, W. Liu, J.G. Power, E.E. Wisniewski ANL, Lemont, Illinois, USA E.A. Frame, P. Piot Northern Illinois University, DeKalb, Illinois, USA
	At the Argonne Wakefield Accelerator (AWA) facility, particle-tracking simulations have been critical to guiding beam-dynamic experiments, e.g., for various beam manipulations using an available emittance-exchange beamline (EEX). The unique beamline available at AWA provide a test case to perform in-depth comparison between different particle-tracking programs including collective effects such as space-charge force and coherent synchrotron radiation. In this study, using AWA electron injector and emittance exchange beamline, we compare the simulations results obtained by GPT, OPAL, and Impact-T beam-dynamics programs. We will specifically report on convergence test as a function of parameters that controls the underlying algorithms.
	Slides WEXD5 [1.847 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEXD5
About •	Received ※ 03 August 2022 — Revised ※ 06 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 22 August 2022
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WEXD6	Electron Cloud Measurements in Fermilab Booster	electron, booster, 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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WEYD4	Design and Fabrication of a Metamaterial Wakefield Accelerating Structure	wakefield, acceleration, experiment, flattop	564
	D.C. Merenich, X. Lu Northern Illinois University, DeKalb, Illinois, USA D.S. Doran, X. Lu, J.G. Power ANL, Lemont, Illinois, USA
	Metamaterials (MTMs) are engineered materials that can show exotic electromagnetic properties such as simultaneously negative permittivity and permeability. MTMs are promising candidates for structure-based wakefield acceleration structures, which can mitigate the impact of radio frequency (RF) breakdown, thus achieving a high gradient. Previous experiments carried out at the Argonne Wakefield Accelerator (AWA) successfully demonstrated MTM structures as efficient power extraction and transfer structures (PETS) from a high-charge drive beam. Here we present the design, fabrication, and cold test of an X-band MTM accelerator structure for acceleration of the witness beam in the two-beam acceleration scheme. The MTM structure design was performed using the CST Studio Suite, with the unit cell and the complete multi-cell periodic structure both optimized for high gradient. Cold test of the fabricated structure shows good agreement with simulation results. Future work includes a beam test at AWA to study the short-pulse RF breakdown physics in the MTM structure, as an important component towards a future compact linear collider based on two-beam acceleration.
	Slides WEYD4 [2.322 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEYD4
About •	Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 31 August 2022
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WEYE4	Electron Cloud Simulations in the Fermilab Recycler	electron, 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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WEYE5	Model/Measurement Comparison of the Transverse Phase Space Distribution of an RFQ-Generated Bunch at the SNS BTF	rfq, MEBT, space-charge, emittance	584
	K.J. Ruisard, A.V. Aleksandrov, S.M. Cousineau, A.M. Hoover, A.P. Zhukov ORNL, Oak Ridge, Tennessee, USA
	Funding: This work is supported by US DOE, Office of Science, HEP. This manuscript is authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with US DOE. The research program at the SNS Beam Test Facility is focused on resolving observed model/measurement discrepancies that preclude accurate loss prediction in high-power linacs. The current program of study is focused on deploying direct 6D measurements to reconstruct a realistic model of the initial beam distribution at the RFQ output. This detailed characterization also provides an opportunity for benchmark of RFQ simulations. Here we compare PARMTEQ predictions against 5D-resolved (x, x’, y, y’, dE) phase space measurements of the BTF H⁻ bunch, focusing on the transverse distribution. This work is an extension of [1], which focused on the longitudinal phase space. [1] K. Ruisard et al., doi: 10.1103/PhysRevAccelBeams.23.124201. [2] A. Hoover et al., "Measurements of the Five-Dimensional Phase Space Distribution of a High-Intensity Ion Beam," these proceedings.
	Slides WEYE5 [2.646 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEYE5
About •	Received ※ 03 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 13 August 2022 — Issue date ※ 04 October 2022
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WEPA08	Design and Operation Experience of a Multi-Collimator/YAG Screen Device on LCLS II Low Energy Beamline	wakefield, radiation, electron, 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
About •	Received ※ 02 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 13 September 2022
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WEPA09	A Parallel Automatic Simulation Tool for Cavity Shape Optimization	cavity, HOM, SRF, gun	634
	L. Ge, Z. Li, C.-K. Ng, L. Xiao SLAC, Menlo Park, California, USA M. Beall, B.R. Downie, O. Klaas Simmetrix Inc., Clifton Park, USA
	Funding: U.S. Department of Energy under contract No. DE-SC0018715. We present a parallel automatic shape optimization workflow for designing accelerator cavities. The newly developed 3D parallel optimization tool Opt3P based on discrete adjoint methods is used to determine the optimal accelerator cavity shape with the desired spectral response. Initial and updated models, meshes, and design velocities of design parameters for defining the cavity shape are generated with Simmetrix tools for mesh generation (MeshSim), geometry modification and query (GeomSim), and user interface tools (SimModeler). Two shape optimization examples using this automatic simulation workflow will be presented here. One is the TESLA cavity with higher-order-mode (HOM) couplers and the other is a superconducting rf (SRF) gun. The objective for the TESLA cavity is to minimize HOM damping factors and for the SRF gun to minimize the surface electric and magnetic fields while maintaining its operating mode frequency at a prescribed value. The results demonstrate that the automatic simulation tool allows an efficient shape optimization procedure with minimal manual operations. All simulations were performed on the NERSC supercomputer Cori system for solution speedup.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA09
About •	Received ※ 03 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 08 October 2022
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WEPA10	Determination of LCLS-II Gun-2 Prototype Dimensions	gun, cavity, cathode, vacuum	637
	L. Xiao, C. Adolphsen, E.N. Jongewaard, X. Liu, F. Zhou SLAC, Menlo Park, California, USA
	The LCLS-II spare gun (Gun-2) design is largely based on the existing LCLS-II gun (Gun-1), in which there is significant captured dark current (DC) that originates on the high field copper surface near the cathode plug gap opening. To help suppress DC, the Gun-2 cathode and anode noses and the cathode plug opening are elliptically shaped to minimize the peak surface field for a given cathode gradient. Stainless steel (SS) cathode and anode inserts are used in Gun-2 to further reduce dark current. The RF simulations were performed using a model that includes all the 3D features. The thermal and structural analyses were done to investigate the effects of the air pressure and RF heating. The multi-physics simulation results provided the information needed to compute the overall frequency change from the basic 2D model to the nominal frequency during operation. The Gun-2 cathode-to-anode gap distance will be made 1 mm longer than the nominal gap with the expectation that less than 1 mm will be machined off to meet the target frequency. In this paper, the Gun-2 frequency correction calculations are presented, and the cathode-to-anode gap determination is discussed.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA10
About •	Received ※ 30 July 2022 — Revised ※ 03 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 10 August 2022
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WEPA12	Operational Experience of the New Booster Cryomodule at the Upgraded Injector Test Facility	cavity, booster, cryomodule, experiment	640
	M.W. Bruker, R. Bachimanchi, J.M. Grames, M.D. McCaughan, J. Musson, P.D. Owen, T.E. Plawski, M. Poelker, T. Powers, H. Wang, Y.W. Wang 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. Since the early 1990s, the injector of the CEBAF accelerator at Jefferson Lab has relied on a normal-conducting RF graded-beta capture section to boost the kinetic energy of the electron beam from 100 / 130 keV to 600 keV for subsequent acceleration using a cryomodule housing two superconducting 5-cell cavities similar to those used throughout the accelerator. To simplify the injector design and improve the beam quality, the normal-conducting RF capture section and the cryomodule will be replaced with a new single booster cryomodule employing a superconducting, β = 0.6, 2-cell-cavity capture section and a single, β = 0.97, 7-cell cavity. The Upgraded Injector Test Facility at Jefferson Lab is currently hosting the new cryomodule to evaluate its performance with beam before installation at CEBAF. While demonstrating satisfactory performance of the booster and good agreement with simulations, our beam test results also speak to limitations of accelerator operations in a noisy, thermally unregulated environment.
	Poster WEPA12 [3.726 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA12
About •	Received ※ 03 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 06 September 2022
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WEPA24	pyJSPEC - A Python Module for IBS and Electron Cooling Simulation	electron, 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
About •	Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 26 August 2022
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WEPA36	Emittance Growth Due to RF Phase Noise in Crab Cavities	cavity, emittance, collider, betatron	708
	H. Huang, S. Zhao ODU, Norfolk, Virginia, USA F. Lin, V.S. Morozov ORNL RAD, Oak Ridge, Tennessee, USA Y. Luo Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA T. Satogata, Y. Zhang JLab, Newport News, Virginia, USA B.P. Xiao, D. Xu BNL, Upton, New York, USA
	The Electron-Ion Collider (EIC) incorporates beam crabbing to recover geometric luminosity loss from the nonzero crossing angle at the interaction point (IP). It is well-known that crab cavity imperfections can cause growth of colliding beam emittances, thus degrading collider performance. Here we report a particle tracking study to quantify these effects. Presently the study is focused on crab cavity RF phase noise. Simulations were carried out using Bmad. Dependence of emittance growth on phase noise level was obtained which could be used for developing crab cavity phase control specifications. We also benchmarked these simulations with theory.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA36
About •	Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 02 September 2022
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WEPA37	Benchmarking and Exploring Parameter Space of the 2-Phase Bubble Tracking Model for Liquid Mercury Target Simulation	target, neutron, experiment, injection	711
	L. Lin, M.I. Radaideh, H. Tran, D.E. Winder ORNL, Oak Ridge, Tennessee, USA
	Funding: This project was funded by the U.S. DOE under grant DE-SC0009915. High intensity proton pulses strike the Spallation Neutron Source (SNS)’s mercury target to provide bright neutron beams. These strikes deposit extensive energy into the mercury and its steel vessel. Prediction of the resultant loading on the target is difficult when helium gas is intentionally injected into the mercury to reduce the loading and to mitigate the pitting damage on the vessel. A 2-phase material model that incorporates the Rayleigh-Plesset (R-P) model is expected to address this complex multi-physics dynamics problem by including the bubble dynamics in the liquid mercury. We present a study comparing the measured target strains in the SNS target station with the simulation results of the solid mechanics simulation framework. We investigate a wide range of various physical model parameters, including the number of bubble families, bubble size distribution, viscosity, surface tension, etc. to understand their impact on simulation accuracy. Our initial findings reveal that using 8-10 bubble families in the model renders a simulation strain envelope that covers the experimental ones. Further optimization studies are planned to predict the strain response more accurately.
	Poster WEPA37 [1.985 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA37
About •	Received ※ 27 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 01 September 2022
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WEPA38	Progress on Machine Learning for the SNS High Voltage Converter Modulators	network, klystron, linac, electron	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
About •	Received ※ 25 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 03 October 2022
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WEPA41	Maximizing Output of 3 MeV S-band Industrial Accelerator	gun, target, ECR, high-voltage	723
	D. Fischer, M. Denney, A.V. Mishin, S. Proskin, J. Roylance, L. Young Varex Imaging, Salt Lake City, USA
	Earlier, we have reported on a record-breaking 3-MeV Accelerator Beam Centerline (ABC) built in 2017-2018. An upgraded version of this 3-MeV S-band ABC has been developed at Varex Imaging as a key component for one of the most popular X-ray industrial linear accelerator systems, commonly used for security and NDT applications. Being significantly strained by excessive backstreaming, increasing of the ABC output is a challenging task. We describe these challenges and highlight high power test results. The triode gun and structure design improvements allowed us to raise stable output up to 530 Rad/min/1m at 3 MeV and up to 220 Rad/min/1m at 4.5 MeV with a widely available 2.5-MW/2.7-kW magnetron, while maintaining the spot size at 2 mm.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA41
About •	Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 20 September 2022
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WEPA43	Self-Contained Linac Irradiator for the Sterile Insect Technique (SIT)	electron, target, linac, 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
About •	Received ※ 04 August 2022 — Revised ※ 06 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 16 September 2022
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WEPA48	Electromagnetic Design of a Compact RF Chopper for Heavy-Ion Beam Separation at FRIB	cavity, dipole, linac, MEBT	738
	A.C. Araujo Martinez, R.B. Agustsson, Y.C. Chen, S.V. Kutsaev RadiaBeam, Santa Monica, California, USA A.S. Plastun, X. Rao FRIB, East Lansing, Michigan, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under SBIR grant DE- SC0020671. Rare isotope beams are produced at FRIB via fragmentation of a primary heavy ion beam in a thin target. The isotope beam of interest is contaminated with other fragments, which must be filtered out to ensure the delivery of rare isotopes with desired rates and purities. One of the stages of fragment separation uses an RF deflecting cavity to provide time-of-flight separation. However, to avoid neighboring bunches overlapping with each other and with the contaminants, it is necessary to increase the inter-bunch distance by a factor of four, corresponding to a 20.125 MHz rate. To solve this problem, we have developed an RF chopper system for the 500 keV/u primary heavy-ion beams. The system consists of a deflecting quarter wave resonator (QWR) cavity operating at 60.375 MHz, two dipole steering magnets, and a beam dump. In this paper, we present and discuss the optimization of the electromagnetic design of the QWR cavity and magnets, as well as some aspects, related to beam dynamics and conceptual engineering design.
DOI •	reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA48
About •	Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 08 September 2022
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WEPA56	Encapsulation of Photocathodes Using High Power Pulsed RF Sputtering of hBN	cathode, electron, 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
About •	Received ※ 31 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 10 August 2022
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Paper

Title

Other Keywords

Page

MOYD3

EIC Transverse Emittance Growth Due to Crab Cavity RF Noise: Estimates and Mitigation

cavity, emittance, feedback, target

6

T. Mastoridis, P. Fuller, P. Mahvi, Y. Matsumura
CalPoly, San Luis Obispo, California, USA

Funding: This work is partially supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Award Number DE-SC-0019287.
The Electron-Ion Collider (EIC) requires crab cavities to compensate for a 25 mrad crossing angle and achieve maximum luminosity. The crab cavity Radio Frequency (RF) system will inject low levels of noise to the crabbing field, generating transverse emittance growth and potentially limiting luminosity lifetime. In this work, we estimate the transverse emittance growth rate as a function of the Crab Cavity RF noise and quantify RF noise specifications for reasonable performance. Finally, we evaluate the possible mitigation of the RF noise induced emittance growth via a dedicated feedback system.

Slides MOYD3 [0.223 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOYD3

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Received ※ 28 July 2022 — Revised ※ 01 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 04 October 2022

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MOYD4

Model Parameters Determination in EIC Strong-Strong Simulation

electron, 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, electron, 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

electron, experiment, 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

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

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MOZE3

Emittance Measurements and Simulations from an X-Band Short-Pulse Ultra-High Gradient Photoinjector

emittance, gun, linac, laser

45

G. Chen, D.S. Doran, C.-J. Jing, S.Y. Kim, W. Liu, W. Liu, P. Piot, J.G. Power, C. Whiteford, E.E. Wisniewski
ANL, Lemont, Illinois, USA
C.-J. Jing, E.W. Knight, S.V. Kuzikov
Euclid TechLabs, Solon, Ohio, USA
C.-J. Jing
Euclid Beamlabs, Bolingbrook, USA
X. Lu, P. Piot, W.H. Tan
Northern Illinois University, DeKalb, Illinois, USA

Funding: This work is supported by the U.S. DOE, under award No. DE-SC0018656 to NIU, DOE SBIR grant No. DE-SC0018709 to Euclid Techlabs LLC, and contract No. DE-AC02-06CH11357 with ANL.
A program is under way at the Argonne Wakefield Accelerator facility, in collaboration with the Euclid Techlabs and Northern Illinois University (NIU), to develop a GeV/m scale photocathode gun, with the ultimate goal of demonstrating a high-brightness photoinjector beamline. The novel X-band photoemission gun (Xgun) is powered by high-power, short RF pulses, 9-ns (FWHM), which, in turn, are generated by the AWA drive beam. In a previous proof-of-principle experiment, an unprecedented 400~MV/m gradient on the photocathode surface* was demonstrated. In the current version of the experiment, we added a linac to the beamline to increase the total energy and gain experience tuning the beamline. In this paper, we report on the very first result of emittance measurement as well as several other beam parameters. This preliminary investigation has identified several factors to be improved on in order to achieve one of the ultimate goals; low emittance.
* W. H. Tan et al., "Demonstration of sub-GV/m Accelerating Field in a Photoemission Electron Gun Powered by Nanosecond X-Band Radiofrequency Pulses", 2022. arXiv:2203.11598v1

Slides MOZE3 [5.565 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZE3

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Received ※ 03 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 14 August 2022

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MOZE4

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

cavity, electron, impedance, accelerating-gradient

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]

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

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

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MOZE5

Simulation and Experimental Results of Dielectric Disk Accelerating Structures

accelerating-gradient, experiment, wakefield, impedance

52

S. Weatherly, E.E. Wisniewski
Illinois Institute of Technology, Chicago, Illinois, USA
D.S. Doran, C.-J. Jing, J.F. Power, E.E. Wisniewski
ANL, Lemont, Illinois, USA
B.T. Freemire, C.-J. Jing
Euclid Beamlabs, Bolingbrook, USA

Funding: Contract DE-SC0019864 to Euclid Beamlabs LLC. AWA work from U.S. DOE Office of Science under Contract DE-AC02-06CH11357. Chicagoland Accelerator Science Traineeship U.S. DOE award number DE-SC-0020379
A method of decreasing the required footprint of linear accelerators and improving their energy efficiency is to employ Dielectric Disk Accelerators (DDAs) with short RF pulses ( ∼ 9 ns). A DDA is an accelerating structure that utilizes dielectric disks to improve the shunt impedance. Two DDA structures have been designed and tested at the Argonne Wakefield Accelerator. A single cell clamped DDA structure recently achieved an accelerating gradient of 1{02} MV/m. A multi-cell clamped DDA structure has been designed and is being fabricated. Simulation results for this new structure show a 1{08} MV/m accelerating gradient with 400 MW of input power with a high shunt impedance and group velocity. The engineering design has been improved from the single cell structure to ensure consistent clamping over the entire structure.

Slides MOZE5 [9.338 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZE5

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Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 21 August 2022 — Issue date ※ 06 October 2022

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MOPA01

Realistic CAD-Based Geometries for Arbitrary Magnets with Beam Delivery Simulation (BDSIM)

vacuum, extraction, synchrotron, proton

55

E. Ramoisiaux, R. Dantinne, E. Gnacadja, C. Hernalsteens, S. Musibau, B. Ndihokubwayo, N. Pauly, R. Tesse, M. Vanwelde
ULB, Bruxelles, Belgium
S.T. Boogert, L.J. Nevay, W. Shields
Royal Holloway, University of London, Surrey, United Kingdom
C. Hernalsteens
CERN, Meyrin, Switzerland

Monte Carlo simulations are required to evaluate beam losses and secondary radiation accurately in particle accelerators and beamlines. Detailed CAD geometries are critical to account for a realistic distribution of material masses but increase the model complexity and often lead to code duplication. Beam Delivery Simulation (BDSIM) and the Python package pyg4ometry enable handling such accelerator models within a single, simplified workflow to run complete simulations of primary and secondary particle tracking and interactions with matter using Geant4 routines. Additional capabilities have been developed to model arbitrary bent magnets by associating externally modeled geometries to the magnet poles, yoke, and beampipe. Individual field descriptions can be associated with the yoke and vacuum pipe separately to provide fine-grained control of the magnet model. The implementation of these new features is described in detail and applied to the modeling of the CERN Proton Synchrotron (PS) combined function magnets.

Poster MOPA01 [0.781 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA01

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Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 16 September 2022

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MOPA02

Activation of the IBA Proteus One Proton Therapy Beamline Using BDSIM and FISPACT-II

proton, neutron, shielding, radiation

59

E. Ramoisiaux, E. Gnacadja, C. Hernalsteens, N. Pauly, R. Tesse, M. Vanwelde
ULB, Bruxelles, Belgium
C. Hernalsteens
CERN, Meyrin, Switzerland

Cyclotron-based proton therapy systems generate large fluxes of secondary particles due to the beam interactions with the beamline elements, with the energy degrader being the dominant source. Compact systems exacerbate these challenges for concrete shielding and beamline element activation. Our implementation of the Rigorous Two-Step method uses Beam Delivery Simulation (BDSIM), a Geant4-based particle tracking code, for primary and secondary particles transport and fluence scoring, and FISPACT-II for time-dependent nuclear inventory and solving the rate equations. This approach is applied to the Ion Beam Applications (IBA) Proteus®ONE (P1) system, for which a complete model has been built, validated, and used for shielding activation simulations. We detail the first simulations of the activation on quadrupole magnets in high-fluence locations downstream of the degrader. Results show the evolution of the long-lived nuclide concentrations for short and long timescales throughout the facility lifetime for a typical operation scenario.

Poster MOPA02 [0.553 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA02

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Received ※ 02 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 19 August 2022 — Issue date ※ 21 September 2022

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MOPA09

Design of a 4D Emittance Diagnostic for Low-Energy Ion Beams

diagnostics, emittance, quadrupole, linac

67

T.R. Curtin, M.S. Curtin
Ion Linac Systems, Inc., Albuquerque, USA

Characterization of ion beams from an ion injector consisting of an electron-cyclotron-resonance (ECR) source in combination with a low-energy-beam-transport (LEBT) typically exhibits a complex four-dimensional transverse phase-space distribution. The importance of measuring the ion beam correlations following extraction and transport of the low-energy beam is critical to enabling optimization of beam transmission through downstream accelerating structures. A design for a transverse, four-dimensional emittance meter for low-energy protons from the Ion Linac Systems (ILS) ECR-LEBT ion injector is provided.

Poster MOPA09 [0.479 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA09

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Received ※ 03 August 2022 — Revised ※ 27 September 2022 — Accepted ※ 05 December 2022 — Issue date ※ 05 December 2022

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MOPA13

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

gun, electron, 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)

electron, solenoid, optics, 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

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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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MOPA29

Second Generation Fermilab Main Injector 8 GeV Beamline Collimation Preliminary Design

collimation, vacuum, shielding, controls

116

K.J. Hazelwood, P. Adamson, B.C. Brown, D. Capista, R.M. Donahue, B.L. Klein, N.V. Mokhov, V.S. Pronskikh, V.I. Sidorov, M.C. Vincent
Fermilab, Batavia, Illinois, USA

The current Fermilab Main Injector 8 GeV beamline transverse collimation system was installed in 2006. Since then, proton beam intensities and rates have increased significantly. With the promise of even greater beam intensities and a faster repetition rate when the PIP-II upgrade completes later this decade, the current collimation system will be insufficient. Over the past 18 months, multiple collimation designs have been investigated, some more traditional and others novel. A preliminary design review was conducted and a design chosen. Work is underway to finalize the chosen design, prototype some of its novel components and procure parts for installation Summer 2023.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA29

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Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 15 August 2022 — Issue date ※ 25 September 2022

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MOPA46

Cryogenic Dielectric Structure with GΩ/m Level Shunt Impedance

impedance, cryogenics, acceleration, accelerating-gradient

157

R.A. Kostin, C. Jing
Euclid Beamlabs, Bolingbrook, USA

Shunt impedance is one of the most important parameters characterizing particle acceleration efficiency. It is known that RF losses are reduced at cryogenic temperatures. For example, a record high shunt impedance of 350 MΩ/m was demonstrated recently for all metal X-band accelerating structure, which is more than 2 times higher than that at room temperature. In this article we present a novel hybrid dielectric structure which can achieve even higher shunt impedance due to the fact that losses in dielectric materials reduced much more than in pure copper.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA46

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Received ※ 12 August 2022 — Revised ※ 16 August 2022 — Accepted ※ 23 August 2022 — Issue date ※ 17 September 2022

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MOPA50

Integrated Photonics Structure Cathodes for Longitudinally Shaped Bunch Trains

wakefield, cathode, emittance, laser

160

S.J. Coleman, D.T. Abell, C.C. Hall
RadiaSoft LLC, Boulder, Colorado, USA
R. Kapadia
University of Southern California, Los Angeles, California, USA
S.S. Karkare
Arizona State University, Tempe, USA
S.Y. Kim, P. Piot, J.F. Power
ANL, Lemont, Illinois, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DOE DE-SC0021681
Compact, high-gradient structure wakefield accelerators can operate at improved efficiency using shaped electron beams, such as a high transformer ratio beam shape, to drive the wakes. These shapes have generally come from a photocathode gun followed by a transverse mask to imprint a desired shape on the transverse distribution, and then an emittance exchanger (EEX) to convert that transverse shape into a longitudinal distribution. This process discards some large fraction of the beam, limiting wall-plug efficiency as well as leaving a solid object in the path of the beam. In this paper, we present a proposed method of using integrated photonics structures to control the emission pattern on the cathode surface. This transverse pattern is then converted into a longitudinal pattern at the end of an EEX. This removes the need for the mask, preserving the total charge produced at the cathode surface. We present simulations of an experimental set-up to demonstrate this concept at the Argonne Wakefield Accelerator.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA50

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Received ※ 03 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 26 August 2022 — Issue date ※ 03 October 2022

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MOPA55

Facilitating Machine Learning Collaborations Between Labs, Universities, and Industry

controls, software, operation, framework

164

J.P. Edelen, D.T. Abell, D.L. Bruhwiler, S.J. Coleman, N.M. Cook, A. Diaw, J.A. Einstein-Curtis, C.C. Hall, M.C. Kilpatrick, B. Nash, I.V. Pogorelov
RadiaSoft LLC, Boulder, Colorado, USA
K.A. Brown
BNL, Upton, New York, USA
S. Calder
ORNL RAD, Oak Ridge, Tennessee, USA
A.L. Edelen, B.D. O’Shea, R.J. Roussel
SLAC, Menlo Park, California, USA
C.M. Hoffmann
ORNL, Oak Ridge, Tennessee, USA
E.-C. Huang
LANL, Los Alamos, New Mexico, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA
C. Tennant
JLab, Newport News, Virginia, USA

It is clear from numerous recent community reports, papers, and proposals that machine learning is of tremendous interest for particle accelerator applications. The quickly evolving landscape continues to grow in both the breadth and depth of applications including physics modeling, anomaly detection, controls, diagnostics, and analysis. Consequently, laboratories, universities, and companies across the globe have established dedicated machine learning (ML) and data-science efforts aiming to make use of these new state-of-the-art tools. The current funding environment in the U.S. is structured in a way that supports specific application spaces rather than larger collaboration on community software. Here, we discuss the existing collaboration bottlenecks and how a shift in the funding environment, and how we develop collaborative tools, can help fuel the next wave of ML advancements for particle accelerators.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA55

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Received ※ 10 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 22 August 2022 — Issue date ※ 01 September 2022

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MOPA59

Prediction of Gaseous Breakdown for Plasma Cleaning of RF Cavities

cavity, plasma, electron, 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, electron, 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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MOPA63

Multiphysics Simulation of the Thermal Response of a Nanofibrous Target in a High-Intensity Beam

target, experiment, radiation, proton

185

W.J. Asztalos
IIT, Chicago, Illinois, USA
S.K. Bidhar, F. Pellemoine
Fermilab, Batavia, Illinois, USA
P. Rath
IIT Bhubaneswar, Jatni, India
Y. Torun
Illinois Institute of Technology, Chicago, Illlinois, USA

Nanofibrous structures are of high interest to the fields of engineering and materials science, and investigation of their properties as well as discovery of novel applications for them both constitute lively areas of research. A very promising application of nanofiber mats lies in the field of accelerator technology: beam targets made from nanofiber mats offer a solution to the problem of advancing the "intensity frontier"–-the limit on the beam intensities that can be realized in fixed target experiments and neutrino production facilities. However, testing has shown that the survivability of these nanofiber targets depends strongly on their manufacturing parameters, such as the packing density of fibers. In this work, we will use multiphysics simulations to perform a thermal study on how nanofiber targets react to high intensity beams, so that the dependency of the targets’ lifetime on their construction parameters can be better understood.

Poster MOPA63 [3.656 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA63

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Received ※ 14 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 04 August 2022 — Issue date ※ 25 August 2022

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MOPA72

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

dipole, experiment, cavity, electron

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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MOPA76

Wakefield Modeling in Sub-THz Dielectric-Lined Waveguides

wakefield, electron, 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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MOPA79

Studying the Emission Characteristics of Field Emission Cathodes with Various Geometries

cathode, emittance, experiment, ECR

226

M.R. Howard, S.M. Lidia
FRIB, East Lansing, Michigan, USA
J.E. Coleman
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the NNSA of US DOE under contract 89233218CNA000001 and partially supported by the US DOE under Cooperative Agreement award number DE-SC0018362 and Michigan State University.
The cathode test stand (CTS) at LANL is designed to hold off voltages of up to 500kV and can supply pulse durations up to 2.6 μs. Using this test stand, we are able to test both field emission and photocathodes with different geometries and materials at various pulse lengths and PFN voltages. Currently, the test stand is used to evaluate field emission using a velvet cathode over various pulse lengths. The CTS employs various diagnostic tools, including E-dots, B-dots, and a scintillator coupled with a pepperpot mask in order to measure the extracted voltage, current, beam distribution, and transverse emittance. Xenos [1] has been used to create and simulate diode geometries that permits study to optimize various beam parameters. These geometries include changing the size and recess of the cathode as well as implementing a Pierce geometry. Here, we will discuss comparisons for various simulated cathodes and how changes in geometry impact given beam parameters.
[1] See https://www.fieldp.com/xenos.html for information about the Xenos software.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA79

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Received ※ 02 August 2022 — Revised ※ 10 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 30 August 2022

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MOPA80

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

photon, heavy-ion, detector, electron

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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MOPA90

Relating Initial Distribution to Beam Loss on the Front End of a Heavy-Ion Linac Using Machine Learning

network, LEBT, emittance, controls

263

A.D. Tran, Y. Hao
FRIB, East Lansing, Michigan, USA
J.L. Martinez Marin, B. Mustapha
ANL, Lemont, Illinois, USA

Funding: This work was supported by a sub-reward from Argonne National Laboratory and supported by the U.S. Department of Energy, under Contract No. DE-AC02-06CH11357.
This work demonstrates using a Neural Network and a Gaussian Process to model the ATLAS front-end. Various neural network architectures were created and trained on the machine settings and outputs to model the phase space projections. The model was then trained on a dataset, with non-linear distortion, to gauge the transferability of the model from simulation to machine.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA90

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Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 11 September 2022

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TUXD6

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

cavity, electron, cathode, 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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TUYE2

Next Generation Computational Tools for the Modeling and Design of Particle Accelerators at Exascale

GPU, software, space-charge, plasma

302

A. Huebl, R. Lehé, C.E. Mitchell, J. Qiang, R.D. Ryne, R.T. Sandberg, J.-L. Vay
LBNL, Berkeley, USA

Funding: Work supported by the Exascale Computing Project (17-SC-20-SC), a collaborative effort of the U.S. DOE SC and the NNSA, resources of NERSC, and by LBNL LDRD under DOE Contract DE-AC02-05CH11231.
Particle accelerators are among the largest, most complex devices. To meet the challenges of increasing energy, intensity, accuracy, compactness, complexity and efficiency, increasingly sophisticated computational tools are required for their design and optimization. It is key that contemporary software take advantage of the latest advances in computer hardware and scientific software engineering practices, delivering speed, reproducibility and feature composability for the aforementioned challenges. A new open source software stack is being developed at the heart of the Beam pLasma Accelerator Simulation Toolkit (BLAST) by LBNL and collaborators, providing new particle-in-cell modeling codes capable of exploiting the power of GPUs on Exascale supercomputers. Combined with advanced numerical techniques, such as mesh-refinement, and intrinsic support for machine learning, these codes are primed to provide ultrafast to ultraprecise modeling for future accelerator design and operations.
[1] J.-L. Vay, A. Huebl, et al, Phys. Plasmas 28, 023105 (2021)
[2] J.-L. Vay, A. Huebl, et al, J. Instr. 16, T10003 (2021)
[3] A. Myers, et al (incl. A. Huebl), Parallel Comput. 108, 102833 (2021)

Slides TUYE2 [9.399 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYE2

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Received ※ 13 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 11 August 2022

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TUZE3

Optimizing the Discovery of Underlying Nonlinear Beam Dynamics

lattice, MMI, linear-dynamics, experiment

335

L.A. Pocher, T.M. Antonsen, L. Dovlatyan, I. Haber, P.G. O’Shea
UMD, College Park, Maryland, USA

Funding: Work supported by US DOE-HEP grants: DE-SC0010301 and DE-SC0022009
One of the DOE-HEP Grand Challenges identified by Nagaitsev et al. relates to the use of virtual particle accelerators for beam prediction and optimization. Useful virtual accelerators rely on efficient and effective methodologies grounded in theory, simulation, and experiment. This paper uses an algorithm called Sparse Identification of Nonlinear Dynamical systems (SINDy), which has not previously been applied to beam physics. We believe the SINDy methodology promises to simplify the optimization of accelerator design and commissioning, particularly where space charge is important. We show how SINDy can be used to discover and identify the underlying differential equation system governing the beam moment evolution. We compare discovered differential equations to theoretical predictions and results from the PIC code WARP modeling. We then integrate the discovered differential system forward in time and compare the results to data analyzed in prior work using a Machine Learning paradigm called Reservoir Computing. Finally, we propose extending our methodology, SINDy for Virtual Accelerators (SINDyVA), to the broader community’s computational and real experiments.

Slides TUZE3 [3.141 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZE3

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Received ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 22 August 2022

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TUZE4

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

electron, 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]

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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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TUZE6

Studies of Ion Instability Using a Gas Injection System

feedback, emittance, injection, experiment

347

J.R. Calvey, M. Borland, L. Emery, P.S. Kallakuri
ANL, Lemont, Illinois, USA

Funding: Work supported by U. S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
Ion trapping occurs when a negatively charged beam ionizes residual gas inside an accelerator vacuum chamber, and the resulting ions become trapped in the beam potential. Trapped ions can cause a variety of undesirable effects, including coherent instability and incoherent emittance growth. Because of the challenging emittance and stability requirements of next generation light sources, ion trapping is a serious concern. To study this effect at the present APS, a gas injection system was designed and installed at two different locations in the ring. The system creates a controlled and localized pressure bump of nitrogen gas, so the resulting ion instability can be studied. Measurements were taken under a wide variety of beam conditions, using a spectrum analyzer, pinhole camera, and bunch-by-bunch feedback system. The feedback system was also used to perform grow-damp measurements, allowing us to measure the growth rate of individual unstable modes. This paper will present some of the results of these experiments. Simulations using the IONEFFECTS element in the particle tracking code elegant will also be presented.

Slides TUZE6 [2.425 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZE6

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Received ※ 03 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 24 August 2022

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TUPA04

Sheet Electron Probe for Beam Tomography

electron, proton, diagnostics, cathode

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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TUPA16

Singularity-Free Exact Dipole Bend Transport Equations

dipole, lattice, GUI, framework

375

D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Department of Energy
Exact transport equations for a pure dipole bend (a bend with a dipole field and nothing else) have been derived and formulated to avoid singularities when evaluated. The transport equations include finite edge angles and no assumption is made in terms of the bending field being matched to the curvature of the coordinate system.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA16

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Received ※ 05 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 16 September 2022

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TUPA18

Promise and Challenges of a Method for 5x5 Sigma Matrix Measurement in a Transport Line

quadrupole, booster, extraction, emittance

382

M. Borland, V. Sajaev, K.P. Wootton
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS) is upgrading the storage ring to a design that requires on-axis injection. Matching between the incoming beam and the ring is important to ensure high injection efficiency. Toward this end, we have developed and tested a method for measuring all σ matrix elements except those related to the time coordinate. We report on challenges inherent in this technique, based on simulation and real-world trials.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA18

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

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TUPA19

Avoiding Combinatorial Explosion in Simulation of Multiple Magnet Errors in Swap-Out Safety Tracking for the Advanced Photon Source Upgrade

photon, lattice, injection, storage-ring

386

M. Borland, R. Soliday
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS) is upgrading the storage ring to a hybrid seven-bend-achromat design with reverse bends, providing a natural emittance of 41 pm at 6 GeV. The small dynamic acceptance entails operation in on-axis swap-out mode. Careful consideration is required of the safety implications of injection with shutters open. Tracking studies require simulation of multiple simultaneous magnet errors, some combinations of which may introduce potentially dangerous conditions. A naive grid scan of possible errors, while potentially very complete, would be prohibitively time-consuming. We describe a different approach using biased sampling of particle distributions from successive scans. We also describe other aspects of the simulations, such as use of 3D field maps and a highly detailed aperture model.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA19

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Received ※ 01 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 10 September 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

electron, 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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TUPA27

Longitudinal Feedback Dynamics in Storage Rings with Small Synchrotron Tunes

feedback, HOM, synchrotron, cavity

405

R.R. Lindberg
ANL, Lemont, Illinois, USA

Funding: This work was supported by U.S. Dept. of Energy Office of Sciences under Contract No. DE-AC02-06CH11357.
We analyze the dynamics of multibunch longitudinal instabilities including bunch-by-bunch feedback under the assumption that the synchrotron tune is small. We find that increasing the feedback response does not always guarantee stability, even in the ideal case with no noise. As an example, we show that if the growth rate of a cavity-driven mode is of the order of the synchrotron frequency, then there are parameter regions for which the instability cannot be controlled by feedback irrespective of its gain. We verify these calculations with tracking simulations relevant to the APS-U, and find that the dynamics do not depend upon whether the longitudinal feedback relies on phase-sensing or energy-sensing technology. Hence, this choice should be dictated by measurement accuracy and noise considerations.

Poster TUPA27 [1.180 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA27

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Received ※ 26 July 2022 — Revised ※ 05 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 26 August 2022

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TUPA28

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

pick-up, detector, electron, 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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TUPA30

Development of a Compact 2D Carbon Beam Scanner for Cancer Therapy

proton, power-supply, magnet-design, radiation

417

B. Mustapha, A. Barcikowski, J.A. Nolen
ANL, Lemont, Illinois, USA
V.P. Derenchuk, P. Osucha
ProNova Solutions, Knoxville, USA
N. Tsoupas
BNL, Upton, New York, USA

Funding: This work was supported by the U.S. Department of Energy, under Contract No. DE-AC02-06CH11357. This research was support through the DOE’s Accelerator Stewardship program.
A novel trapezoidal coil 2D carbon beam scanner has been designed, and a prototype has been successfully developed and tested. The field performance of the magnet has been characterized and it is in excellent agreement with the simulations. A better than 1% field uniformity in both planes has been achieved within the useful aperture of the magnet. This represents a significant improvement over the prior art of the elephant-ear scanner design. A comparison of the two designs and the results from the new trapezoidal-coil design will be presented and discussed. Higher power and online beam testing are planned in the near future.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA30

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Received ※ 25 July 2022 — Revised ※ 14 August 2022 — Accepted ※ 15 August 2022 — Issue date ※ 25 August 2022

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TUPA32

SCU Ends Configured as Phase Shifter

undulator, FEL, electron, 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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TUPA34

Model-Based Calibration of Control Parameters at the Argonne Wakefield Accelerator

network, controls, gun, wakefield

427

I.P. Sugrue, B. Mustapha, P. Piot, J.G. Power
ANL, Lemont, Illinois, USA
N. Krislock
Northern Illinois University, DeKalb, Illinois, USA

Particle accelerators utilize a large number of control parameters to generate and manipulate beams. Digital models and simulations are often used to find the best operating parameters to achieve a set of given beam parameters. Unfortunately, the optimized physics parameters cannot precisely be set in the control system due to, e.g., calibration uncertainties. We developed a data-driven physics-informed surrogate model using neural networks to replace digital models relying on beam-dynamics simulations. This surrogate model can then be used to perform quick diagnostics of the Argonne Wakefield accelerator in real time using nonlinear least-squares methods to find the most likely operating parameters given a measured beam distribution.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA34

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Received ※ 05 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 24 September 2022

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TUPA42

LANSCE Modernization Project at LANL

rfq, experiment, proton, LEBT

443

D.V. Gorelov, J. Barraza, D.A.D. Dimitrov, I. Draganić, E. Henestroza, S.S. Kurennoy
LANL, Los Alamos, New Mexico, USA

In the framework of LANSCE Accelerator Modernization Project preliminary research, during evaluation of critical technology elements it was found that the proposed RFQ design had not yet been demonstrated experimentally worldwide. Such an RFQ should combine the ability of traditional light ion RFQs (i.e., [1]) and the flexibility of acceleration of pre-bunched beams, like RFQs for heavy ions [2]. The proposed RFQ should be able to accelerate H⁺ and H⁻ beams with 35-mA beam current from 100 keV to 3 MeV and at the same time preserve the prescribed macro-bunch beam time structure required by experiments. New algorithms for RFQ geometry generation have been proposed, and optimization algorithms are being developed at LANL. LAMP demonstration plans also include development of a new set of electrodes for the existing RFQ at our Test Stand that will allow us to demonstrate the critical technology ahead of time in a laboratory experimental setup with low duty factor and low energy.
[1] S. Henderson et al., Nucl. Instrum. Methods Phys. Res., Sect. A, v. 763, pp. 610-673 (2014).
[2] H. Ren et al., J. Phys. Conf. Ser., v. 1067, 052010 (2018).

Poster TUPA42 [0.635 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA42

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Received ※ 04 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 18 August 2022

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TUPA48

Effect of Lattice Misalignments on Beam Dynamics in LANSCE Linear Accelerator

alignment, emittance, linac, lattice

455

Y.K. Batygin, S.S. Kurennoy
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by US DOE under contract 89233218CNA000001
Accelerator channel misalignments can significantly affect beam parameters in long linear accelerators. Measurements of misalignments of the LANSCE linac lattice elements was performed by the Mechanical Design Engineering Group of the Los Alamos Accelerator Operations and Technology Division. In order to determine effect of misalignment on beam parameters in LANSCE linac, the start-to-end simulations of LANSCE accelerator were performed using Beampath and CST codes including measured displacements of quadrupoles and accelerating tanks. Simulations were done for both H⁺ and H⁻ beams with various beam flavors. Effect of misalignments was compared with those due to beam space charge and distortion of RF field along the channel. Paper presents results of simulation and comparison with experimental data of beam emittance growth along the machine.

Poster TUPA48 [1.547 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA48

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Received ※ 23 July 2022 — Revised ※ 28 July 2022 — Accepted ※ 04 August 2022 — Issue date ※ 14 August 2022

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TUPA53

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

network, electron, 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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TUPA57

Electromagnetic and Beam Dynamics Modeling of the LANSCE Coupled-Cavity Linac

cavity, linac, emittance, quadrupole

472

S.S. Kurennoy, Y.K. Batygin, D.V. Gorelov
LANL, Los Alamos, New Mexico, USA

The 800-MeV proton linac at LANSCE consists of a drift-tube linac, which brings the beam to 100 MeV, followed by a coupled-cavity linac (CCL) consisting of 44 modules. Each CCL module contains multiple tanks, and it is fed by a single 805-MHz klystron. CCL tanks are multi-cell blocks of identical re-entrant side-coupled cavities, which are followed by drifts with magnetic quadrupole doublets. Bridge couplers - special cavities displaced from the beam axis - electromagnetically couple CCL tanks over such drifts. We have developed 3D CST models of CCL tanks. Their electromagnetic analysis is performed using MicroWave Studio. Beam dynamics is modeled with Particle Studio for bunch trains with realistic beam distributions using the CST calculated RF fields and quadrupole magnetic fields to determine the output beam parameters. Beam dynamics results are crosschecked with other multi-particle codes.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA57

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Received ※ 15 July 2022 — Revised ※ 01 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 19 August 2022

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TUPA73

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

cavity, electron, 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

electron, plasma, radiation, 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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TUPA80

Cyborg Beamline Development Updates

gun, cathode, cavity, cryogenics

512

G.E. Lawler, A. Fukasawa, N. Majernik, J.R. Parsons, J.B. Rosenzweig, Y. Sakai
UCLA, Los Angeles, California, USA
F. Bosco
Sapienza University of Rome, Rome, Italy
Z. Li, S.G. Tantawi
SLAC, Menlo Park, California, USA
B. Spataro
LNF-INFN, Frascati, Italy

Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE Contract DE-SC0020409.
Xray free electron laser (XFEL) facilities in their current form are large, costly to maintain, and inaccessible due to their minimal supply and high demand. It is then advantageous to consider miniaturizing XFELs through a variety of means. We hope to increase beam brightness from the photoinjector via high gradient operation (>120 MV/m) and cryogenic temperature operation at the cathode (<77K). To this end we have designed and fabricated our new CrYogenic Brightness-Optimized Radiofrequency Gun (CYBGORG). The photogun is 0.5 cell so much less complicated than our eventual 1.6 cell photoinjector. It will serve as a prototype and test bed for cathode studies in a new cryogenic and very high gradient regime. We present here the fabricated structure, progress towards commissioning, and beamline simulations.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA80

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Received ※ 02 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 09 October 2022

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TUPA82

Transverse Stability in an Alternating Symmetry Planar Dielectric Wakefield Structure

wakefield, experiment, accelerating-gradient, quadrupole

519

W.J. Lynn, G. Andonian, N. Majernik, S.M. OTool, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
D.S. Doran, S.Y. Kim, J.F. Power, E.E. Wisniewski
ANL, Lemont, Illinois, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA

Funding: DE-SC0017648 - AWA.
Dielectric Wakefield Acceleration (DWA) is a promising technique for realizing the next generation of linear colliders. It provides access to significantly higher accelerating gradients than traditional radio-frequency cavities. One impediment to realizing a DWA-powered accelerator is the issue of the transverse stability of the beams within the dielectric structure due to short-range wakefields. These short-range wakefields have a tendency to induce a phenomenon known as single-bunch beam breakup, which acts as its name implies and destroys the relevant beam. We attempt to solve this issue by leveraging the quadrupole mode excited in a planar dielectric structure and then alternating the orientation of said structure to turn an unstable system into a stable one. We examine this issue computationally to determine the limits of stability and based on those simulations describe a future experimental realization of this strategy.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA82

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Received ※ 02 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 30 September 2022

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TUPA83

Derivative-Free Optimization of Multipole Fits to Experimental Wakefield Data

wakefield, multipole, experiment, electron

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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TUPA84

Reconstructing Beam Parameters from Betatron Radiation Through Machine Learning and Maximum Likelihood Estimation

radiation, betatron, diagnostics, plasma

527

S. Zhang, N. Majernik, B. Naranjo, J.B. Rosenzweig, M. Yadav
UCLA, Los Angeles, California, USA
Ö. Apsimon, C.P. Welsch, M. Yadav
The University of Liverpool, Liverpool, United Kingdom

Funding: US Department of Energy, Division of High Energy Physics, under Contract No. DE-SC0009914.
The dense drive beam used in plasma wakefield acceleration generates a linear focusing force that causes electrons inside the witness beam to undergo betatron oscillations, giving rise to betatron radiation. Because information about the properties of the beam is encoded in the betatron radiation, measurements of the radiation such as those recorded by the UCLA-built Compton spectrometer can be used to reconstruct beam parameters. Two possible methods of extracting information about beam parameters from measurements of radiation are machine learning (ML), which is increasingly being implemented for different fields of beam diagnostics, and a statistical technique known as maximum likelihood estimation (MLE). We assess the ability of both machine learning and MLE methods to accurately extract beam parameters from measurements of betatron radiation.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA84

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Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 05 October 2022

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TUPA87

Simulations for the Space Plasma Experiments at the SAMURAI Lab

electron, plasma, 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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WEXD5

Benchmarking Simulation for AWA Drive Linac and Emittance Exchange Beamline Using OPAL, GPT, and Impact-T

emittance, linac, gun, solenoid

552

S.Y. Kim, G. Chen, D.S. Doran, G. Ha, W. Liu, J.G. Power, E.E. Wisniewski
ANL, Lemont, Illinois, USA
E.A. Frame, P. Piot
Northern Illinois University, DeKalb, Illinois, USA

At the Argonne Wakefield Accelerator (AWA) facility, particle-tracking simulations have been critical to guiding beam-dynamic experiments, e.g., for various beam manipulations using an available emittance-exchange beamline (EEX). The unique beamline available at AWA provide a test case to perform in-depth comparison between different particle-tracking programs including collective effects such as space-charge force and coherent synchrotron radiation. In this study, using AWA electron injector and emittance exchange beamline, we compare the simulations results obtained by GPT, OPAL, and Impact-T beam-dynamics programs. We will specifically report on convergence test as a function of parameters that controls the underlying algorithms.

Slides WEXD5 [1.847 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEXD5

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Received ※ 03 August 2022 — Revised ※ 06 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 22 August 2022

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WEXD6

Electron Cloud Measurements in Fermilab Booster

electron, booster, 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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WEYD4

Design and Fabrication of a Metamaterial Wakefield Accelerating Structure

wakefield, acceleration, experiment, flattop

564

D.C. Merenich, X. Lu
Northern Illinois University, DeKalb, Illinois, USA
D.S. Doran, X. Lu, J.G. Power
ANL, Lemont, Illinois, USA

Metamaterials (MTMs) are engineered materials that can show exotic electromagnetic properties such as simultaneously negative permittivity and permeability. MTMs are promising candidates for structure-based wakefield acceleration structures, which can mitigate the impact of radio frequency (RF) breakdown, thus achieving a high gradient. Previous experiments carried out at the Argonne Wakefield Accelerator (AWA) successfully demonstrated MTM structures as efficient power extraction and transfer structures (PETS) from a high-charge drive beam. Here we present the design, fabrication, and cold test of an X-band MTM accelerator structure for acceleration of the witness beam in the two-beam acceleration scheme. The MTM structure design was performed using the CST Studio Suite, with the unit cell and the complete multi-cell periodic structure both optimized for high gradient. Cold test of the fabricated structure shows good agreement with simulation results. Future work includes a beam test at AWA to study the short-pulse RF breakdown physics in the MTM structure, as an important component towards a future compact linear collider based on two-beam acceleration.

Slides WEYD4 [2.322 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEYD4

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Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 31 August 2022

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WEYE4

Electron Cloud Simulations in the Fermilab Recycler

electron, 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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WEYE5

Model/Measurement Comparison of the Transverse Phase Space Distribution of an RFQ-Generated Bunch at the SNS BTF

rfq, MEBT, space-charge, emittance

584

K.J. Ruisard, A.V. Aleksandrov, S.M. Cousineau, A.M. Hoover, A.P. Zhukov
ORNL, Oak Ridge, Tennessee, USA

Funding: This work is supported by US DOE, Office of Science, HEP. This manuscript is authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with US DOE.
The research program at the SNS Beam Test Facility is focused on resolving observed model/measurement discrepancies that preclude accurate loss prediction in high-power linacs. The current program of study is focused on deploying direct 6D measurements to reconstruct a realistic model of the initial beam distribution at the RFQ output. This detailed characterization also provides an opportunity for benchmark of RFQ simulations. Here we compare PARMTEQ predictions against 5D-resolved (x, x’, y, y’, dE) phase space measurements of the BTF H⁻ bunch, focusing on the transverse distribution. This work is an extension of [1], which focused on the longitudinal phase space.
[1] K. Ruisard et al., doi: 10.1103/PhysRevAccelBeams.23.124201.
[2] A. Hoover et al., "Measurements of the Five-Dimensional Phase Space Distribution of a High-Intensity Ion Beam," these proceedings.

Slides WEYE5 [2.646 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEYE5

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Received ※ 03 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 13 August 2022 — Issue date ※ 04 October 2022

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WEPA08

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

wakefield, radiation, electron, 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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WEPA09

A Parallel Automatic Simulation Tool for Cavity Shape Optimization

cavity, HOM, SRF, gun

634

L. Ge, Z. Li, C.-K. Ng, L. Xiao
SLAC, Menlo Park, California, USA
M. Beall, B.R. Downie, O. Klaas
Simmetrix Inc., Clifton Park, USA

Funding: U.S. Department of Energy under contract No. DE-SC0018715.
We present a parallel automatic shape optimization workflow for designing accelerator cavities. The newly developed 3D parallel optimization tool Opt3P based on discrete adjoint methods is used to determine the optimal accelerator cavity shape with the desired spectral response. Initial and updated models, meshes, and design velocities of design parameters for defining the cavity shape are generated with Simmetrix tools for mesh generation (MeshSim), geometry modification and query (GeomSim), and user interface tools (SimModeler). Two shape optimization examples using this automatic simulation workflow will be presented here. One is the TESLA cavity with higher-order-mode (HOM) couplers and the other is a superconducting rf (SRF) gun. The objective for the TESLA cavity is to minimize HOM damping factors and for the SRF gun to minimize the surface electric and magnetic fields while maintaining its operating mode frequency at a prescribed value. The results demonstrate that the automatic simulation tool allows an efficient shape optimization procedure with minimal manual operations. All simulations were performed on the NERSC supercomputer Cori system for solution speedup.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA09

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Received ※ 03 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 08 October 2022

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WEPA10

Determination of LCLS-II Gun-2 Prototype Dimensions

gun, cavity, cathode, vacuum

637

L. Xiao, C. Adolphsen, E.N. Jongewaard, X. Liu, F. Zhou
SLAC, Menlo Park, California, USA

The LCLS-II spare gun (Gun-2) design is largely based on the existing LCLS-II gun (Gun-1), in which there is significant captured dark current (DC) that originates on the high field copper surface near the cathode plug gap opening. To help suppress DC, the Gun-2 cathode and anode noses and the cathode plug opening are elliptically shaped to minimize the peak surface field for a given cathode gradient. Stainless steel (SS) cathode and anode inserts are used in Gun-2 to further reduce dark current. The RF simulations were performed using a model that includes all the 3D features. The thermal and structural analyses were done to investigate the effects of the air pressure and RF heating. The multi-physics simulation results provided the information needed to compute the overall frequency change from the basic 2D model to the nominal frequency during operation. The Gun-2 cathode-to-anode gap distance will be made 1 mm longer than the nominal gap with the expectation that less than 1 mm will be machined off to meet the target frequency. In this paper, the Gun-2 frequency correction calculations are presented, and the cathode-to-anode gap determination is discussed.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA10

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Received ※ 30 July 2022 — Revised ※ 03 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 10 August 2022

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WEPA12

Operational Experience of the New Booster Cryomodule at the Upgraded Injector Test Facility

cavity, booster, cryomodule, experiment

640

M.W. Bruker, R. Bachimanchi, J.M. Grames, M.D. McCaughan, J. Musson, P.D. Owen, T.E. Plawski, M. Poelker, T. Powers, H. Wang, Y.W. Wang
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.
Since the early 1990s, the injector of the CEBAF accelerator at Jefferson Lab has relied on a normal-conducting RF graded-beta capture section to boost the kinetic energy of the electron beam from 100 / 130 keV to 600 keV for subsequent acceleration using a cryomodule housing two superconducting 5-cell cavities similar to those used throughout the accelerator. To simplify the injector design and improve the beam quality, the normal-conducting RF capture section and the cryomodule will be replaced with a new single booster cryomodule employing a superconducting, β = 0.6, 2-cell-cavity capture section and a single, β = 0.97, 7-cell cavity. The Upgraded Injector Test Facility at Jefferson Lab is currently hosting the new cryomodule to evaluate its performance with beam before installation at CEBAF. While demonstrating satisfactory performance of the booster and good agreement with simulations, our beam test results also speak to limitations of accelerator operations in a noisy, thermally unregulated environment.

Poster WEPA12 [3.726 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA12

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Received ※ 03 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 06 September 2022

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WEPA24

pyJSPEC - A Python Module for IBS and Electron Cooling Simulation

electron, 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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WEPA36

Emittance Growth Due to RF Phase Noise in Crab Cavities

cavity, emittance, collider, betatron

708

H. Huang, S. Zhao
ODU, Norfolk, Virginia, USA
F. Lin, V.S. Morozov
ORNL RAD, Oak Ridge, Tennessee, USA
Y. Luo
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
T. Satogata, Y. Zhang
JLab, Newport News, Virginia, USA
B.P. Xiao, D. Xu
BNL, Upton, New York, USA

The Electron-Ion Collider (EIC) incorporates beam crabbing to recover geometric luminosity loss from the nonzero crossing angle at the interaction point (IP). It is well-known that crab cavity imperfections can cause growth of colliding beam emittances, thus degrading collider performance. Here we report a particle tracking study to quantify these effects. Presently the study is focused on crab cavity RF phase noise. Simulations were carried out using Bmad. Dependence of emittance growth on phase noise level was obtained which could be used for developing crab cavity phase control specifications. We also benchmarked these simulations with theory.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA36

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Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 02 September 2022

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WEPA37

Benchmarking and Exploring Parameter Space of the 2-Phase Bubble Tracking Model for Liquid Mercury Target Simulation

target, neutron, experiment, injection

711

L. Lin, M.I. Radaideh, H. Tran, D.E. Winder
ORNL, Oak Ridge, Tennessee, USA

Funding: This project was funded by the U.S. DOE under grant DE-SC0009915.
High intensity proton pulses strike the Spallation Neutron Source (SNS)’s mercury target to provide bright neutron beams. These strikes deposit extensive energy into the mercury and its steel vessel. Prediction of the resultant loading on the target is difficult when helium gas is intentionally injected into the mercury to reduce the loading and to mitigate the pitting damage on the vessel. A 2-phase material model that incorporates the Rayleigh-Plesset (R-P) model is expected to address this complex multi-physics dynamics problem by including the bubble dynamics in the liquid mercury. We present a study comparing the measured target strains in the SNS target station with the simulation results of the solid mechanics simulation framework. We investigate a wide range of various physical model parameters, including the number of bubble families, bubble size distribution, viscosity, surface tension, etc. to understand their impact on simulation accuracy. Our initial findings reveal that using 8-10 bubble families in the model renders a simulation strain envelope that covers the experimental ones. Further optimization studies are planned to predict the strain response more accurately.

Poster WEPA37 [1.985 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA37

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Received ※ 27 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 01 September 2022

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WEPA38

Progress on Machine Learning for the SNS High Voltage Converter Modulators

network, klystron, linac, electron

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]

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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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WEPA41

Maximizing Output of 3 MeV S-band Industrial Accelerator

gun, target, ECR, high-voltage

723

D. Fischer, M. Denney, A.V. Mishin, S. Proskin, J. Roylance, L. Young
Varex Imaging, Salt Lake City, USA

Earlier, we have reported on a record-breaking 3-MeV Accelerator Beam Centerline (ABC) built in 2017-2018. An upgraded version of this 3-MeV S-band ABC has been developed at Varex Imaging as a key component for one of the most popular X-ray industrial linear accelerator systems, commonly used for security and NDT applications. Being significantly strained by excessive backstreaming, increasing of the ABC output is a challenging task. We describe these challenges and highlight high power test results. The triode gun and structure design improvements allowed us to raise stable output up to 530 Rad/min/1m at 3 MeV and up to 220 Rad/min/1m at 4.5 MeV with a widely available 2.5-MW/2.7-kW magnetron, while maintaining the spot size at 2 mm.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA41

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Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 20 September 2022

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WEPA43

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

electron, target, linac, 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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WEPA48

Electromagnetic Design of a Compact RF Chopper for Heavy-Ion Beam Separation at FRIB

cavity, dipole, linac, MEBT

738

A.C. Araujo Martinez, R.B. Agustsson, Y.C. Chen, S.V. Kutsaev
RadiaBeam, Santa Monica, California, USA
A.S. Plastun, X. Rao
FRIB, East Lansing, Michigan, USA

Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under SBIR grant DE- SC0020671.
Rare isotope beams are produced at FRIB via fragmentation of a primary heavy ion beam in a thin target. The isotope beam of interest is contaminated with other fragments, which must be filtered out to ensure the delivery of rare isotopes with desired rates and purities. One of the stages of fragment separation uses an RF deflecting cavity to provide time-of-flight separation. However, to avoid neighboring bunches overlapping with each other and with the contaminants, it is necessary to increase the inter-bunch distance by a factor of four, corresponding to a 20.125 MHz rate. To solve this problem, we have developed an RF chopper system for the 500 keV/u primary heavy-ion beams. The system consists of a deflecting quarter wave resonator (QWR) cavity operating at 60.375 MHz, two dipole steering magnets, and a beam dump. In this paper, we present and discuss the optimization of the electromagnetic design of the QWR cavity and magnets, as well as some aspects, related to beam dynamics and conceptual engineering design.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA48

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Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 08 September 2022

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WEPA56

Encapsulation of Photocathodes Using High Power Pulsed RF Sputtering of hBN

cathode, electron, 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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WEPA63

Extensions of the Complex (IQ) Baseband RF Cavity Model Including RF Source and Beam Interactions

cavity, controls, beam-loading, linac

767

S.P. Jachim, B.J. Cook, J.R.S. Falconer
Arizona State University, Tempe, USA

Funding: This work was supported in part by NSF award #1935994.
This paper extends prior work describing a complex envelope (i.e., baseband) dynamic model of excited accelerator RF cavities, including the effects of frequency detuning, beam loading, reflections, multiple drive ports, and parasitic modes. This model is presented here in closed-form transfer function and state-variable realizations, which may be more appropriate for analytic purposes. Several example simulations illustrate the detailed insight into RF system behavior afforded by this model.

DOI •

reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA63

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Received ※ 28 July 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 15 August 2022

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WEPA67

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

hadron, electron, kicker, 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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WEPA72

Analysis of Beam-Induced Heating of the NSLS-II Ceramic Vacuum Chambers

impedance, kicker, vacuum, injection

799

G. Bassi, C. Hetzel, A. Khan, B.N. Kosciuk, M. Seegitz, V.V. Smaluk, R.J. Todd
BNL, Upton, New York, USA
A. Blednykh
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA

We discuss impedance calculations and related heating issues of the titanium-coated NSLS-II kicker ceramic chambers, with the titanium coating thickness estimated from in situ measurements of the end-to-end resistance of each chamber. Power densities are calculated on the titanium coating to allow for thermal analysis with the code ANSYS and comparison with heating measurements. The impedance analysis is performed using a realistic model of the ceramic complex permittivity, and special consideration is given to the impedance calculation in the limit of zero titanium coating thickness.

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA72

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Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 26 September 2022

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WEPA73

Numerical Studies of Geometric Impedance at NSLS-II with GdfidL and ECHO3D

impedance, vacuum, wakefield, radiation

802

A. Khan, M. Seegitz, V.V. Smaluk, R.J. Todd
BNL, Upton, New York, USA
A. Blednykh
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA

The beam intensity in future low-emittance light sources with small gap wigglers and undulators is limited by the effects of short-range wakefields, especially by the beam-induced heating of the vacuum chamber components. We have cross-checked two electromagnetic solvers, GdfidL and ECHO3D, by simulation of the short-range wakefields in the NSLS-II flange absorber and in the taper transition of an in-vacuum undulator to test the consistency and precision of the wakefield models.

Poster WEPA73 [1.057 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA73

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Received ※ 01 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 01 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, proton, electron

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.

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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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WEPA83

Extended Soft-Gaussian Code for Beam-Beam Simulations

electron, 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, electron, 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.

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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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THYD4

Progress on the APS-U Injector Upgrade

booster, injection, storage-ring, target

859

J.R. Calvey, T. Fors, K.C. Harkay, U. Wienands
ANL, Lemont, Illinois, USA

Funding: Work supported by U. S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
For the APS-Upgrade, it was decided to leave the present APS injector chain in place and make individual improvements where needed. The main challenges faced by the injectors are delivering a high charge bunch (up to 16 nC in a single shot) to the storage ring, operating the booster synchrotron and storage ring at different rf frequencies, and maintaining good charge stability during APS-U operations. This paper will summarize recent progress on the injector upgrade. Topics include bucket targeting with the new injection/extraction timing system (IETS), modeling of high charge longitudinal instability in the PAR, and measurements of charge stability for different modes of operation.

Slides THYD4 [2.015 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THYD4

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Received ※ 19 July 2022 — Accepted ※ 11 August 2022 — Issue date ※ 22 August 2022

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THYD5

Development of Nanopatterned Strong Field Emission Cathodes

cathode, electron, laser, brightness

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]

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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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FRXD3

Measurements of the Five-Dimensional Phase Space Distribution of an Intense Ion Beam

emittance, neutron, rfq, quadrupole

910

A.M. Hoover, A.V. Aleksandrov, S.M. Cousineau, K.J. Ruisard, A.P. Zhukov
ORNL, Oak Ridge, Tennessee, USA

Funding: Supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics; authored by UT- Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.
No simulation of intense beam transport has accurately reproduced measurements at the level of beam halo. One potential explanation of this discrepancy is a lack of knowledge of the initial distribution of particles in six-dimensional (6D) phase space. A direct 6D measurement of an ion beam was recently performed at the Spallation Neutron Source (SNS) Beam Test Facility (BTF), revealing nonlinear transverse-longitudinal correlations in the beam core that affect downstream evolution. Unfortunately, direct 6D measurements are limited in resolution and dynamic range; here, we discuss the use of three slits and one screen to measure a 5D projection of the 6D phase space distribution, overcoming these limitations at the cost of one dimension. We examine the measured 5D distribution before and after transport through the BTF and compare to particle-in-cell simulations. We also discuss the possibility of reconstructing the 6D distribution from 5D and 4D projections.

Slides FRXD3 [4.078 MB]

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reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-FRXD3

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Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 02 September 2022

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FRXD4

Suppressing the Microbunching Instability at ATF using Laser Assisted Bunch Compression

laser, electron, experiment, 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, electron, 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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