Multi-Domain Plasma Expansion Simulations Using a Particle-in-Cell Method
ENGINEERING RESEARCH AND CONSULTING INC (ERC INC) EDWARDS AFB CA
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The statistical nature of the Particle-In-Cell PIC algorithm for plasma modeling requires that a large number of computational particles is used per cell to reduce the numerical noise. This requirement presents a computational obstacle in cases involving rapidly decaying plasmas, such as in simulations of plume expansion from electric propulsion EP thrusters. The simulation domain typically contains plasma densities ranging from 1017 to 1010 particlescubic meter. Several approaches for retaining a sufficient per-cell particle count exist, including growth of simulation cells, particle splitting, and particle tracking limited to the back flowing particles, but none of these is without associated problems. In this paper, we present an alternative approach based on a multi-domain modeling. A coarse simulation is used to sample particle flux into a subdomain enclosing the region of interest. A second simulation is then performed on the subdomain, with particles injected at domain boundaries according to the prescribed flux. This approach is used to predict ion current to a simple cylindrical probe located on a satellite using a cluster of four Hall thrusters for primary propulsion. The effect of sheath resolution is investigated and results are compared to an analytical model.
- Plasma Physics and Magnetohydrodynamics
- Electric and Ion Propulsion