Paper  Title  Other Keywords  Page 

MOZD4  Uncertainty Quantification of Beam Parameters in a Linear Induction Accelerator Inferred from Bayesian Analysis of Solenoid Scans  solenoid, experiment, electron, spacecharge  34 


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 flashradiography 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 chisquarelike 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 MarkovChain 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 LAUR016585. November 2001. 

Slides MOZD4 [1.082 MB]  
DOI •  reference for this paper ※ doi:10.18429/JACoWNAPAC2022MOZD4  
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 


Funding: This work was supported by the office of Science, under US Department of Energy contract number DEAC0205CH11231. 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 Nb_{3}Sn 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 Nb_{3}Sn 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 runaway 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 MOPA42 [1.498 MB]  
DOI •  reference for this paper ※ doi:10.18429/JACoWNAPAC2022MOPA42  
About •  Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 23 August 2022  
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TUZE4  ParticleinCell Simulations of High Current Density Electron Beams in the Scorpius Linear Induction Accelerator  simulation, electron, emittance, plasma  339 


Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DEAC5207NA27344. Particleincell (PIC) simulations of a high current density (I > 1 kA), and highly relativistic electron beam (E ~ 220 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 nextgeneration flash Xray 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. * LLNLABS830595, Approved for public release. Distribution Unlimited. 

Slides TUZE4 [4.305 MB]  
DOI •  reference for this paper ※ doi:10.18429/JACoWNAPAC2022TUZE4  
About •  Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 21 September 2022  
Cite •  reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  