Keyword: MMI
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MOPA12 Commissioning of HOM Detectors in the First Cryomodule of the LCLS-II Linac HOM, cavity, alignment, cryomodule 69
  • J.A. Diaz Cruz
    UNM-ECE, Albuquerque, USA
  • B.T. Jacobson, N.R. Neveu, J.P. Sikora
    SLAC, Menlo Park, California, USA
  Long-range wakefields (LRWs) may cause emittance dilution effects. LWRs are especially unwanted at facilities with low emittance beams like the LCLS-II at SLAC. Dipolar higher-order modes (HOMs) are a set of LRWs that are excited by off-axis beams. Two 4-channel HOM detectors were built to measure the beam-induced HOM signals for TESLA-type superconducting RF (SRF) cavities; they were tested at the Fermilab Accelerator Science and Technology (FAST) facility and are now installed at SLAC. The HOM detectors were designed to investigate LRW effects on the beam and to help with beam alignment. This paper presents preliminary results of HOM measurements at the first cryomodule (CM01) of the LCLS-II linac and describes the relevant hardware and setup of the experiment.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA12  
About • Received ※ 09 August 2022 — Accepted ※ 20 August 2022 — Issue date ※ 31 August 2022  
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MOPA30 LCLS-II BCS Average Current Monitor cavity, electron, hardware, LLRF 120
  • N.M. Ludlow, T.L. Allison, J.P. Sikora, J.J. Welch
    SLAC, Menlo Park, California, USA
  LCLS-II is a 4th generation light source at the SLAC National Accelerator Laboratory. LCLS-II will accelerate a 30 µA electron beam with a 1 MHz bunch rate with a new superconducting Continuous Waveform (CW) RF accelerator. The Average Current Monitor (ACM) is part of the Beam Containment System (BCS) for the LCLS-II accelerator. The Beam Containment System is a safety system that provides paths to safely shut the accelerator beam off under a variety of conditions. The Average Current Monitor is a beam diagnostic within the BCS that is used to verify that the accelerator is producing the appropriate current level and to limit beam power to allowed values to protect the machine and beam dumps. The average beam current is obtained by measuring the power level induced by the beam in a low Q cavity. By knowing the Q, the beta, and the coupling of the cavity, the instantaneous charge can be calculated, then integrating the instantaneous charge over one millisecond will yield the average current. This paper will discuss progress in the checkout process of the ACM LLRF hardware leading to LCLS-II commissioning.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA30  
About • Received ※ 16 July 2022 — Revised ※ 05 August 2022 — Accepted ※ 24 August 2022 — Issue date ※ 06 October 2022
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MOPA84 Superconducting Cavity Commissioning for the FRIB Linac cavity, cryomodule, controls, linac 242
  • W. Chang, W. Hartung, S.H. Kim, T. Konomi, S.R. Kunjir, J.T. Popielarski, K. Saito, T. Xu, S. Zhao
    FRIB, East Lansing, Michigan, USA
  The superconducting driver linac for the Facility for Rare Isotope Beams (FRIB) is a heavy ion accelerator that has 46 cryomodules with 324 superconducting (SC) cavities that accelerate ions to 200 MeV per nucleon. Linac commissioning was done in multiple phases, in parallel with technical installation. Ion beam have now been accelerated to the design energy through the full linac; rare isotopes were first produced in December 2021; and the first user experiment was completed in May 2022. All cryomodules were successfully commissioned. Cryomodule commissioning included establishing the desired cavity fields, measuring field emission X-rays, optimizing the tuner control loops, measuring the cavity dynamic heat load, and confirming the low-level RF control (amplitude and phase stability). Results on cryomodule commissioning and cryomodule performance will be presented.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA84  
About • Received ※ 13 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 13 August 2022 — Issue date ※ 05 September 2022
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TUYD6 Design of a 200 kV DC Cryocooled Photoemission Gun for Photocathode Investigations cathode, gun, electron, cryogenics 292
  • G.S. Gevorkyan, T.J. Hanks, A.H. Kachwala, S.S. Karkare, C.J. Knill, C.A. Sarabia Cardenas
    Arizona State University, Tempe, USA
  Funding: This work was supported by the U.S. National Science Foundation under Award No. PHY-1549132, the Center for Bright Beams, and the DOE under Grant No. DE-SC0021092.
We present the first results of the commissioning of the 200 kV DC electron gun with a cryogenically cooled cathode at Arizona State University. The gun is specifically designed for studying a wide variety of novel cathode materials including single crystalline and epitaxially grown materials at 30 K temperatures to obtain the lowest possible intrinsic emittance of UED and XFEL applications [1]. We will present the measurements of the cryogenic performance of the gun and the first high voltage commissioning results.
[1] G. S. Gevorkyan et. al., Proc. of NAPAC19 MOPLM16 (2019)
slides icon Slides TUYD6 [12.632 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYD6  
About • Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 29 September 2022
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TUZE3 Optimizing the Discovery of Underlying Nonlinear Beam Dynamics lattice, simulation, 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 icon 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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TUPA59 RF System Upgrade for Low Energy DTL Cavity at LANSCE controls, DTL, LLRF, cavity 478
  • J.T.M. Lyles, R.E. Bratton, T.W. Hall, M. Sanchez Barrueta
    LANL, Los Alamos, New Mexico, USA
  Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract 89233218CNA000001.
The Los Alamos Neutron Science Center (LANSCE) 100-MeV Drift Tube Linac (DTL) uses four accelerating cavities. In May of 2021, a new RF amplifier system was commissioned to drive the first 4-MeV cavity. It had been powered for 30 years with a triode vacuum tube RF amplifier driven by a tetrode, along with four more vacuum tubes for anode high-voltage modulation. The new amplifier system uses one tetrode amplifier driven by a 20-kW solid state amplifier (SSA) to generate 400 kWp at 201.25 MHz. The tetrode amplifier is protected for reflected power from the DTL by a coaxial circulator. The new installation includes cRio controls and a fast protection and monitoring system capable of reacting to faults within 10 µs. A new digital low-level RF (LLRF) system has been installed that integrates I/Q signal processing, PI feedback, and feedforward controls for beam loading compensation. Issues with LLRF stability were initially encountered due to interaction from thermal-related RF phase changes. After these issues were solved, the final outcome has been a reliable new RF system to complete the overall upgrade of the LANSCE DTL RF power plant.
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA59  
About • Received ※ 03 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 12 August 2022
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TUPA75 High Gradient Testing Results of the Benchmark a/λ=0.105 Cavity at CERF-NM cavity, GUI, klystron, coupling 505
  • M.R.A. Zuboraj, D.V. Gorelov, T.W. Hall, M.E. Middendorf, D. Rai, E.I. Simakov, T. Tajima
    LANL, Los Alamos, New Mexico, USA
  Funding: This work was supported by Los Alamos National Laboratory’s Laboratory Directed Research and Development (LDRD) Program.
This presentation will report initial results of high gradient testing of two C-band accelerating cavities fabricated at Los Alamos National Laboratory (LANL). At LANL, we commissioned a C-band Engineering Research Facility of New Mexico (CERF-NM) which has unique capability of conditioning and testing accelerating cavities for operation at surface electric fields at the excess of 300 MV/m, powered by a 50 MW, 5.712 GHz Canon klystron. Recently, we fabricated and tested two benchmark copper cavities at CERF-NM. These cavities establish a benchmark for high gradient performance at C-band and the same geometry will be used to provide direct comparison between high gradient performance of cavities fabricated of different alloys and by different fabrication methods. The cavities consist of three cells with one high gradient central cell and two coupling cells on the sides. The ratio of the radius of the coupling iris to the wavelength is a/λ=0.105. This poster will report high gradient test results such as breakdown rates as function of peak surface electric and magnetic fields and pulse heating.
poster icon Poster TUPA75 [0.890 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA75  
About • Received ※ 05 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 01 October 2022
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WEYE2 Upgrade of the FRIB ReAccelerator cryomodule, experiment, cavity, ion-source 572
  • A.C.C. Villari, B. Arend, G. Bollen, D.B. Crisp, K.D. Davidson, K. Fukushima, A.I. Henriques, K. Holland, S.H. Kim, A. Lapierre, Y. Liu, T. Maruta, D.G. Morris, S. Nash, P.N. Ostroumov, A.S. Plastun, J. Priller, S. Schwarz, B.M. Sherrill, M. Steiner, C. Sumithrarachchi, R. Walker, T. Zhang, Q. Zhao
    FRIB, East Lansing, Michigan, USA
  Funding: Work supported by the NSF under grant PHY15-65546 and DOE-SC under award number DE-SC0000661
The reaccelerator facility at FRIB was upgraded to provide new science opportunities. The upgrade included a new ion source to produce stable and long livied rare isotopes in a batch mode, a new room-temperature rebuncher, a new β = 0.085 quarter-wave-resonator cryomodule to increase the beam energy from 3 MeV/u to 6 MeV/u for ions with a charge-to-mass ratio of 1/4, and a new experimental vault with beamlines.
slides icon Slides WEYE2 [4.220 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEYE2  
About • Received ※ 13 July 2022 — Revised ※ 01 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 10 August 2022
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WEZD6 Manufacturing the Harmonic Kicker Cavity Prototype for the Electron-Ion Collider cavity, kicker, electron, collider 601
  • S.A. Overstreet, M.W. Bruker, G.A. Grose, J. Guo, J. Henry, G.-T. Park, R.A. Rimmer, H. Wang, R.S. Williams
    JLab, Newport News, Virginia, USA
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177
High-bunch-frequency beam-separation schemes, such as the injection scheme proposed for the Rapid Cycling Synchrotron at the Electron-Ion Collider, demand rise and fall times an order of magnitude below what can realistically be accomplished with a stripline kicker. Nanosecond-time-scale kick waveforms can instead be obtained by Fourier synthesis in a harmonically resonant quarter-wave radio-frequency cavity which is optimized for high shunt impedance. Originally developed for the Jefferson Lab Electron-Ion Collider (JLEIC) Circulator Cooler Ring, a hypothetical 11-pass ring driven by an energy-recovery linac at Jefferson Lab, our high-power prototype of such a harmonic kicker cavity, which operates at five modes at the same time, will demonstrate the viability of this concept with a beam test at Jefferson Lab. As the geometry of the cavity, tight mechanical tolerances, and number of ports complicate the design and manufacturing process, special care must be given to the order of the manufacturing steps. We present our experiences with the manufacturability of the present design, lessons learned, and first RF test results from the prototype.
slides icon Slides WEZD6 [12.312 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEZD6  
About • Received ※ 04 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 18 August 2022 — Issue date ※ 31 August 2022
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WEPA32 Spallation Neutron Source Cryogenic Moderator System Helium Gas Analysis System cryogenics, neutron, operation, target 699
  • B. DeGraff, L. Pinion
    ORNL RAD, Oak Ridge, Tennessee, USA
  • R. Armstrong, J. Denison, M.P. Howell, S.-H. Kim, D. Montierth
    ORNL, Oak Ridge, Tennessee, USA
  • M.D. Williamson
    LBNL, Berkeley, California, USA
  Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) operates the Cryogenic Moderator System (CMS). The CMS comprises a 20-K helium refrigerator and three helium to hydrogen heat exchangers in support of hydrogen cooled spallation moderation vessels. This system uses vessels filled with activated carbon as the final major component to remove oil vapor from the compressed helium in the cryogenic cold box. SNS uses a LINDE multi-component gas analyzer to detect the presence of contaminants in the warm helium flow upstream of the cold box including aerosolized oil vapor. The design challenges of installing and operating this analyzer on the CMS system due to normal system operating pressures will be discussed. The design, fabrication, installation, commissioning, and initial results of this system operation will be presented. Future upgrades to the analyzer system will also be discussed.
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA32  
About • Received ※ 06 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 05 October 2022
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WEPA45 Practical Review on Beam Line Commissioning Procedures and Techniques for Scientific and Industrial Electron Accelerators electron, emittance, operation, linac 735
  • M.O. Kravchenko, R.D. Berry, A. Diego, D.I. Gavryushkin, M. Ruelas
    RadiaBeam, Santa Monica, California, USA
  Accelerator science has a constant demand requiring improved electron beam quality for both scientific and industrial applications. Examples of parameters on existing systems that affect overall beam quality include: vacuum stability, component level alignment, RF phase matching, electron injection parameters, etc. A proper beam commissioning process allows the characterization of initial parameters that tune system setup appropriately in order to improve net beam quality and becomes a valuable source of data to guide system operation. Here we will discuss methods and possible obstacles during the commissioning process of accelerator systems experienced at RadiaBeam. This includes a description of the diagnostic equipment that may be used to commission a beam line such as: current transformers, faraday cups, profile monitors and pyro detectors. The interpretation of raw data from the diagnostics in terms of usefulness for further adjustments and improvements on the beam line as shown in current work. Simulations and empirical comparisons are also presented as examples for commissioning procedures within the aspect of expectations and actual results.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA45  
About • Received ※ 30 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 09 August 2022
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THXD4 Online Accelerator Tuning with Adaptive Bayesian Optimization photon, controls, toolkit, software-tool 842
  • N. Kuklev, M. Borland, G.I. Fystro, H. Shang, Y. Sun
    ANL, Lemont, Illinois, USA
  Funding: The work is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Particle accelerators require continuous adjustment to maintain beam quality. At the Advanced Photon Source (APS) this is accomplished using a mix of operator-controlled and automated tools. To improve the latter, we explored the use of machine learning (ML) at the APS injector complex. The core approach we chose was Bayesian optimization (BO), which is well suited for sparse data tasks. To enable long-term online use, we modified BO into adaptive Bayesian optimization (ABO) though auxiliary models of device drift, physics-informed quality and constraint weights, time-biased data subsampling, digital twin retraining, and other approaches. ABO allowed for compensation of changes in inputs and objectives without discarding previous data. Benchmarks showed better ABO performance in several simulated and experimental cases. To integrate ABO into the operational workflow, we developed a Python command line utility, pysddsoptimize, that is compatible with existing Tcl/Tk tools and the SDDS data format. This allowed for fast implementation, debugging, and benchmarking. Our results are an encouraging step for the wider adoption of ML at APS.
slides icon Slides THXD4 [4.797 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THXD4  
About • Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 08 October 2022
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THZD1 Instant Phase Setting in a Large Superconducting Linac cavity, linac, SRF, experiment 885
  • A.S. Plastun, P.N. Ostroumov
    FRIB, East Lansing, Michigan, USA
  Funding: This work is supported by the U.S. Department of Energy Office of Science under Cooperative Agreement No. DE-SC0000661, the State of Michigan, and Michigan State University.
The instant phase setting reduces the time needed to setup 328 radiofrequency cavities of the Facility for Rare Isotope Beams (FRIB) linac from 20 hours to 10 minutes. This technique uses a 1-D computer model of the linac to predict the cavities’ phases. The model has been accurately calibrated using the data of the 360-degree phase scans - a common procedure for phasing of linear accelerators. The model was validated by comparison with a conventional phase scan results. The predictions applied to the linac are then verified by multiple time-of-flight energy measurements and the response of the beam position/phase monitors (BPMs) to an intentional energy and phase mismatch. The presented approach not just reduces the time and the effort required to tune the FRIB accelerator for new experiments every couple of weeks, but it also provides an easy recovery from cavity failures. It is beneficial for user facilities requiring high beam availability, as well as for radioactive ion beam accelerators, where quick time-of-flight energy measurement via the BPMs is not possible due to the low intensities of these beams.
slides icon Slides THZD1 [2.610 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THZD1  
About • Received ※ 07 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 21 August 2022
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THZE4 Experimental Characterization of Gas Sheet Transverse Profile Diagnostic diagnostics, electron, laser, operation 907
  • N. Burger, G. Andonian, D.I. Gavryushkin, T.J. Hodgetts, A.-L.M.S. Lamure, M. Ruelas
    RadiaBeam, Santa Monica, California, USA
  • N.M. Cook, A. Diaw
    RadiaSoft LLC, Boulder, Colorado, USA
  • P.E. Denham, P. Musumeci, A. Ody
    UCLA, Los Angeles, USA
  • N.P. Norvell
    UCSC, Santa Cruz, California, USA
  • C.P. Welsch, M. Yadav
    The University of Liverpool, Liverpool, United Kingdom
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  Transverse profile diagnostics for high-intensity beams require solutions that are non-intercepting and single-shot. In this paper, we describe a gas-sheet ionization diagnostic that employs a precision-shaped, neutral gas jet. As the high-intensity beam passes through the gas sheet, neutral particles are ionized. The ionization products are transported and imaged on a detector. A neural-network based reconstruction algorithm, trained on simulation data, then outputs the initial transverse conditions of the beam prior to ionization. The diagnostic is also adaptable to image the photons from recombination. Preliminary tests at low energy are presented to characterize the working principle of the instrument, including comparisons to existing diagnostics. The results are parametrized as a function of beam charge, spot size, and bunch length.  
slides icon Slides THZE4 [2.051 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THZE4  
About • Received ※ 02 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 09 October 2022
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