Speakers
Description
This work presents Particle-in-Cell (PIC) simulations using WarpX [1] to study neutral beam injection (NBI) [2] physics in Wisconsin HTS Axisymmetric Mirror (WHAM) [3-5]-class beamlines as part of a DOE INFUSE collaboration between Realta Fusion and Lawrence Berkeley National Laboratory. The goal is to develop a self-consistent model that couples beam extraction, gas neutralization, re-ionization, and space-charge compensation. The neutralization model is verified against an analytic matrix formulation for charge-state evolution, and the accelerator model is benchmarked against a published WHAM-relevant positive-ion NBI configuration. WarpX reproduces the single-aperture extracted current and captures the reference downstream beam divergence. The coupled simulation further shows that primary electrons generated by impact ionization reduce the beam potential by about 80%, identifying the dominant space-charge neutralization mechanism. These results establish a benchmarked positive-ion NBI modeling workflow for future multi-aperture WHAM simulations and advanced negative-ion or photo-neutralized beam concepts.
Funding Agency
DOE INFUSE program under CRADA No. FP00019597. Simulations were performed at NERSC under Contract No. DE-AC02 05CH11231 using NERSC award FES-ERCAP0026655.
Footnotes
[1] J. -L. Vay et al., “WarpX: An advanced Particle-In-Cell code”
[2] R. Koch, “Plasma heating by neutral beam injection”
[3] D. Endrizzi et al., “Physics basis for the Wisconsin HTS axisymmetric mirror (WHAM)”
| Paper status | Resubmitted proceeding files received and assigned to an editor. Accepted. |
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