Keyword: space-charge
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MOZD4 Uncertainty Quantification of Beam Parameters in a Linear Induction Accelerator Inferred from Bayesian Analysis of Solenoid Scans solenoid, experiment, electron, induction 34
  • M.A. Jaworski, D.C. Moir, S. Szustkowski
    LANL, Los Alamos, New Mexico, USA
  Linear induction accelerators (LIAs) such as the DARHT at Los Alamos National Laboratory make use of the beam envelope equation to simulate the beam and design experiments. Accepted practice is to infer beam parameters using the solenoid scan technique with optical transition radiation (OTR) beam profiles. These scans are then analyzed with an envelope equation solver to find a solution consistent with the data and machine parameters (beam energy, current, magnetic field, and geometry). The most common code for this purpose with flash-radiography LIAs is xtr [1]. The code assumes the machine parameters are perfectly known and that beam profiles will follow a normal distribution about the best fit and solves by minimizing a chi-square-like metric. We construct a Bayesian model of the beam parameters allowing maching parameters, such as solenoid position, to vary within reasonable uncertainty bounds. Posterior distribution functions are constructed using Markov-Chain Monte Carlo (MCMC) methods to evaluate the accuracy of the xtr solution uncertainties and the impact of finite precision in measurements.
[1] P.W. Allison, "Beam dynamics equations for xtr," Los Alamos Technical Report LA-UR-01-6585. November 2001.
slides icon Slides MOZD4 [1.082 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZD4  
About • Received ※ 05 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 20 August 2022
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MOPA33 Waker Experiments at Fermilab Recycler Ring experiment, feedback, kicker, impedance 124
  • O. Mohsen, R. Ainsworth, N. Eddy
    Fermilab, Batavia, Illinois, USA
  Attaining high-intensity hadron beams is often limited due to the transverse collective instabilities, whose understanding is thus required to see and possibly extend the intensity limitations. To explore such instabilities, a novel artificial wake system, the waker, has been built and tested at the Fermilab Recycler Ring (RR). In this report, we show recent upgrades of the waker. Also, we present experimental studies of instabilities at various space charge and wake parameters.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA33  
About • Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 28 August 2022
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MOPA64 Circular Modes for Mitigating Space-Charge Effects and Enabling Flat Beams quadrupole, emittance, optics, coupling 189
  • O. Gilanliogullari
    IIT, Chicago, Illinois, USA
  • B. Mustapha
    ANL, Lemont, Illinois, USA
  • P. Snopok
    Illinois Institute of Technology, Chicago, Illlinois, USA
  Funding: This work was supported by the U.S. Department of Energy, under Contract No. DE-AC02-06CH11357
Flat beams are preferred in high-intensity accelerators and high-energy colliders due to one of the transverse plane emittances being smaller, which enhances luminosity and beam brightness. However, flat beams are devastating at low energies due to space charge forces which are significantly enhanced in one plane. The same is true, although to a lesser degree, for non-symmetric elliptical beams. In order to mitigate this effect, circular mode beam optics can be used. In this paper, we show that circular mode beams dilute space charge effects at lower energies, and can be transformed to flat beams later on.
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA64  
About • Received ※ 09 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 23 August 2022
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MOPA69 Adjoint Optimization Applied to Flat to Round Transformers solenoid, quadrupole, lattice, electron 199
  • T.M. Antonsen, B.L. Beaudoin, S. Bernal, L. Dovlatyan, I. Haber, P.G. O’Shea, D.F. Sutter
    UMD, College Park, Maryland, USA
  Funding: This work was supported by DOE-HEP Awards No. DESC0010301 and DESC0022009
We present the numerical optimization, using adjoint techniques, of Flat-to-Round (FTR) transformers operating in the strong self-field limit. FTRs transform an unmagnetized beam that has a high aspect ratio, elliptical spatial cross section, to a round beam in a solenoidal magnetic field. In its simplest form the flat to round conversion is accomplished with a triplet of quadrupoles, and a solenoid. FTR transformers have multiple applications in beam physics research, including manipulating electron beams to cool co-propagating hadron beams. Parameters that can be varied to optimize the FTR conversion are the positions and strengths of the four magnet elements, including the orientations and axial profiles of the quadrupoles and the axial profile and strength of the solenoid’s magnetic field. The adjoint method we employ [1] allows for optimization of the lattice with a minimum computational effort including self-fields. The present model is based on a moment description of the beam. However, the generalization to a particle description will be presented. The optimized designs presented here will be tested in experiments under construction at the University of Maryland.
[1] Optimization of Flat to Round Transformers with self-fields using adjoint techniques, L. Dovlatyan, B. Beaudoin, S. Bernal, I. Haber, D. Sutter and TMA, PhysRevAccelBeams.25.044002 (2022).
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA69  
About • Received ※ 03 August 2022 — Revised ※ 25 September 2022 — Accepted ※ 05 December 2022 — Issue date ※ 05 December 2022
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MOPA82 Space Charge Driven Third Order Resonance at AGS Injection resonance, experiment, emittance, injection 236
  • M.A. Balcewicz, Y. Hao
    FRIB, East Lansing, Michigan, USA
  • Y. Hao, H. Huang, C. Liu, K. Zeno
    BNL, Upton, New York, USA
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy
Resonance line crossings at significant space charge tune shifts can exhibit various phenomena due to periodic resonance crossing from synchrotron motion* and manifests as halo generation and bunch shortening along with the more mundane emittance growth and beam loss. An injection experiment is conducted at the AGS using the fast wall current monitor and electron collecting Ionization Profile Monitor (eIPM) to probe third order resonances to better characterize the resonance crossing over a 4 ms time scale. This experiment shows some agreement with previous experiments, save for lack of bunch shortening, possibly due to relative resonance strength.
* G. Franchetti et al. PRSTAB 13, 114203. 2010
poster icon Poster MOPA82 [1.924 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA82  
About • Received ※ 02 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 19 August 2022 — Issue date ※ 24 August 2022
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TUXD6 Dual Radiofrequency Cavity Based Monochromatization for High Resolution Electron Energy Loss Spectroscopy cavity, electron, cathode, simulation 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 icon 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 simulation, GPU, software, 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 icon 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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WEYE5 Model/Measurement Comparison of the Transverse Phase Space Distribution of an RFQ-Generated Bunch at the SNS BTF rfq, simulation, MEBT, 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 icon 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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WEYE6 Thermionic Sources for Electron Cooling at IOTA electron, vacuum, cathode, proton 588
  • M.K. Bossard, Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
  • N. Banerjee, J.A. Brandt
    Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
  • B.L. Cathey, S. Nagaitsev, G. Stancari
    Fermilab, Batavia, Illinois, USA
  • M.A. Krieg
    Saint Olaf College, Northfield, MN, USA
  We are planning a new electron cooling experiment at the Integrable Optics Test Accelerator (IOTA) at Fermilab for cooling ~2.5 MeV protons in the presence of intense space-charge. Here we present the simulations and design of a thermionic electron source for cooling at IOTA. We particularly discuss parameters of the thermionic source electrodes, as well as the simulation results. We also present a new electron source test-stand at the University of Chicago, which will be used to test the new thermionic electron source, as well as other electron sources. In addition, we discuss results from analyzing the test stand operations with a currently existing electron source. Furthermore, we present future steps for the test stand as well as production and commissioning of the thermionic source at IOTA.  
slides icon Slides WEYE6 [3.182 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEYE6  
About • Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 28 August 2022
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WEPA34 Transfer Maps in the Hard-Edge Limit of Quadrupole and Bend Magnets Fringe Fields quadrupole, dipole, collider, linear-dynamics 705
  • T.V. Gorlov
    ORNL, Oak Ridge, Tennessee, USA
  Funding: This work has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.
Beam dynamics of charged particles in the fringe field of a quadrupole and a dipole magnet is considered. An effective method for solving symplectic Lie map exp(:f:) in such cases has been developed. A precise analytic solution for nonlinear transverse beam dynamics in a quadrupole magnet with hard-edge fringe field has been obtained. The method of Lie map calculation considered here can be applied for other magnets and for soft edge type of fringe field.
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA34  
About • Received ※ 23 July 2022 — Revised ※ 29 July 2022 — Accepted ※ 07 August 2022 — Issue date ※ 12 August 2022
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