Particle simulation of an anode-layer Hall thruster plume using an anisotropic scattering model

Abstract

The large-angle scattered ions are generated in the plasma plume mainly due to the ion-atom collisions. These ions can induce thrust loss, backflow, or sputtering on the spacecraft. It is necessary, therefore, to give an accurate prediction of ion movement for the study on electric propulsions. In the present work, a particle simulation procedure, which includes (1) a Direct Simulation Monte Carlo method and (2) a particle-in-cell method with a Monte Carlo collisions technique coupled with an anisotropy scattering model, is applied to simulate the plume of a D55 anode-layer Hall thruster. The effective Xe+-Xe and Xe2+-Xe interaction potentials are employed to simulate the ion-atom scattering. The electron properties are obtained via a Boltzmann relation and a model that utilizes conservation-law-type equations, respectively. Comparisons are made between the experimental data together with the simulation results from the anisotropy model and those from an isotropic scattering model to analyze their disparities. Results show that, compared with the isotropic model, the electron number density from the anisotropy model matches better with the experimental data. However, the differences in ion current density, plasma potential, and electron temperature between the two scattering models are insignificant. The anisotropy model can give a more accurate prediction of the ion energy distribution, resulting from its more reasonable hypothesis than the isotropic model. For different electron models, the computed results from one using conservation-law-type equations are in better agreement with the measurements than a simple Boltzmann relation.