Keyword: induction
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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, space-charge 34
  • M.A. Jaworski, D.C. Moir, S. Szustkowski
    LANL, Los Alamos, New Mexico, USA
  Linear induction accelerators (LIAs) such as the DARHT at Los Alamos National Laboratory make use of the beam envelope equation to simulate the beam and design experiments. Accepted practice is to infer beam parameters using the solenoid scan technique with optical transition radiation (OTR) beam profiles. These scans are then analyzed with an envelope equation solver to find a solution consistent with the data and machine parameters (beam energy, current, magnetic field, and geometry). The most common code for this purpose with flash-radiography LIAs is xtr [1]. The code assumes the machine parameters are perfectly known and that beam profiles will follow a normal distribution about the best fit and solves by minimizing a chi-square-like metric. We construct a Bayesian model of the beam parameters allowing maching parameters, such as solenoid position, to vary within reasonable uncertainty bounds. Posterior distribution functions are constructed using Markov-Chain Monte Carlo (MCMC) methods to evaluate the accuracy of the xtr solution uncertainties and the impact of finite precision in measurements.
[1] P.W. Allison, "Beam dynamics equations for xtr," Los Alamos Technical Report LA-UR-01-6585. November 2001.
slides 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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MOPA42 Considerations Concerning the Use of HTS Conductor for Accelerator Dipoles with Inductions above 15 T dipole, quadrupole, superconductivity, niobium 143
  • M.A. Green
    LBNL, Berkeley, California, USA
  Funding: This work was supported by the office of Science, under US Department of Energy contract number DE-AC-02-05CH11231.
The use of high temperature superconductors for accelerator dipole has been discussed for about twenty years and maybe a little more. Conductors that can potentially be used for accelerator magnets have been available for about fifteen years. These conductors are REBCO tape conductors, which can be wound into coils with no reaction after winding, and BISSCO cable conductors, which require reaction after winding and insulation after reaction in a process similar to Nb3Sn cables. Both conductors are expensive and the process after reacting is expensive. Some unknown factors that remain: Will either conductor degrade in current carrying capacity with repeated cycling like Nb3Sn cables do? The other two issues are problems for both types of HTS conductors and they are; 1) quench protection in the event of a normal region run-away and 2) dealing with the superconducting magnetization inherent with HTS cables and tapes. This paper will discuss the last two issues and maybe will provide a partial solution to these problems.
poster icon Poster MOPA42 [1.498 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA42  
About • Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 23 August 2022
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TUZE4 Particle-in-Cell Simulations of High Current Density Electron Beams in the Scorpius Linear Induction Accelerator simulation, electron, emittance, plasma 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 icon 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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