Kinetic Simulations of Plasma Plume Potential in a Vacuum Chamber

Direct simulation Monte Carlo and particle-in-cell simulations are carried out to study the potential of a mesothermal plasma plume in a vacuum chamber. The results show that the beam potential with respect to the ambient in a vacuum chamber is different from that in space because the facility plasma can prematurely terminate the plume expansion process. As a result, the plume potential measured in a vacuum chamber may be significantly lower than that under the in-space condition. This can lead to underestimation of the backflow of charge-exchange ions and ionized contaminants in plasma thruster plume modeling.