2024/12/05 by Aaron Tran, Samuel J. Frank, Tran, Aaron +25 · 2 citations
Earth and Planetary Sciences · Engineering · Physics and Astronomy · #FOS: Physical sciences #Ionosphere and magnetosphere dynamics #Ocean Waves and Remote Sensing #Plasma Physics (physics.plasm-ph) #Underwater Vehicles and Communication Systems
paper · pdf · doi:10.48550/arxiv.2412.04656
openalex publication_date 2024/12/05 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The kinetic stability of collisionless, sloshing beam-ion (45° pitch angle) plasma is studied in a 3D simple magnetic mirror, mimicking the Wisconsin High-temperature superconductor Axisymmetric Mirror (WHAM) experiment. The collisional Fokker-Planck code CQL3D-m provides a slowing-down beam-ion distribution to initialize the kinetic-ion/fluid-electron code Hybrid-VPIC, which then simulates free plasma decay without external heating or fueling. Over 1-10 μs, drift-cyclotron loss-cone (DCLC) modes grow and saturate in amplitude. DCLC scatters ions to a marginally-stable distribution with gas-dynamic rather than classical-mirror confinement. Sloshing ions can trap cool (low-energy) ions in an electrostatic potential well to stabilize DCLC, but DCLC itself does not scatter sloshing beam-ions into said well. Instead, cool ions must come from external sources such as charge-exchange collisions with a low-density neutral population. Manually adding cool ~1 keV ions improves beam-ion confinement several-fold in Hybrid-VPIC simulations, which qualitatively corroborates prior measurements from real mirror devices with sloshing ions.