Modeling of Hall thruster plume sputtering and contamination

This paper describes two modeling approaches developed at Lockheed Martin Missiles and Space Operations for analysis of the sputter erosion of spacecraft surfaces due to use of Hall thrusters. The PIC-DSMC (Particle in Cell-Direct Simulation Monte Carlo) plume model developed at Massachusetts Institute of Technology was successfully modified to model the BPT-4000 thruster (4.5 kW, 350 V) plumes. In addition to modeling the complicated plume features using the PIC-DSMC code, we also developed a semi-empirical plume model that requires less computational time for modeling the sputter erosion of spacecraft surfaces. The approach uses PLIMP (Plume Impingement) code as a ray-tracing tool to determine the plume distances from the exit to impinged objects (e.g. solar arrays), plume divergence angles, and impingement angles. Measured ion current flux and sputter rates were then used to examine the sputtering erosion for solar arrays on a representative geostationary spacecraft. This simi-empirical model allows one to perform a quick spacecraft-plume interaction investigation. Moreover, contamination deposition of eroded thruster products and sputtered spacecraft materials was examined.