Speaker
Description
We present particle-in-cell simulations of a high-current Penning discharge using the semi-implicit electrostatic solver in WarpX [1]. The method reaches experimentally relevant conditions, with discharge currents of several amperes and plasma densities near 1e18 m-3. The modeled 3 A configuration includes two independently biased crescent-shaped anode segments [2]. The simulations show the coexistence of a low-frequency spoke and higher-frequency spiral-arm structures even when the averaged electric field is directed outward. The dominant spoke frequency is about 100 kHz, while spiral-arm structures form over a broadband range near 1 MHz. The anode current shows that the spoke gives the dominant contribution to current oscillations, consistent with experiment [2]. We examine dependence on neutral pressure, magnetic field, anode biasing, and gas composition. Higher neutral pressure suppresses mode activity, shifts the spectrum to lower frequencies, and reduces current noise. Stronger magnetic fields excite additional spoke-like modes and increase current noise. Asymmetric anode biasing reduces instability amplitude, while gas-mixture scans reveal differences in cross-field ion transport.
| Email address | mikhail.tyushev@usask.ca |
|---|---|
| Funding Agency | Digital Research Alliance of Canada, NSERC |
| Visitor's Visa | no |
| Classification | Numerical simulations of sources, beams, space-charge, ion-optics |
| Footnote | [1] Likhanskii et al., GEC 2023, Volume 68, Number 9, ER2.00004. [2] Kim et al., Plasma Sources Sci. Technol. 31 (5), 05LT02 (2022). |