Numerical Investigation of Neutral-Injection Effect on an Electrodeless Plasma Thruster

Abstract

The effect of neutral gas injection from downstream side of electrodeless thrusters is numerically investigated using two-dimensional axisymmetric particle-in-cell simulations with Monte Carlo collisions algorithm (PIC/MCC) for charged particles, and direct simulation Monte Carlo (DSMC) for neutrals, where the propellant gas is injected from both the upstream and downstream sides of the source cavity. The analysis is performed for various ratios of the gas injection from the upstream and downstream sides, while maintaining the total gas flow rate of 30 μg/s. The PIC/MCC and DSMC numerical results show that the performance degradation induced by neutral depletion is inhibited and the plasma density peak shifts to the downstream side of the source when increasing the downstream gas injection. As a result, the downstream gas injection is effective for performance improvement by applying external magnetic fields. This tendency is in qualitative agreement with recent experiments.