Numerical investigation of reversed gas feed configurations for Hall thrusters

TL;DR

This paper numerically investigates a reversed gas feed configuration for Hall thrusters, demonstrating it can significantly improve mass utilization efficiency compared to standard direct injection methods.

Contribution

It introduces and analyzes a reversed gas feed design for Hall thrusters, showing potential efficiency improvements over traditional configurations.

Findings

Reversed injection increases mass utilization efficiency from 2-5% to 20-30%.

Neutral density and velocity fields are characterized under different conditions.

Residence time of neutrals is quantified, informing design optimization.

Abstract

A reversed gas feed configuration for Hall thrusters is proposed and studied numerically. As an alternative to standard direct injection, we investigate the effect of injecting the propellant near the channel exit and directing it backwards, towards the anode. The resulting neutral density and average velocity fields are studied with the Direct Simulation Monte Carlo method for both cold and warm anode conditions. The residence time of neutral particles inside the channel and in the ionization region is computed using a test-particle Monte Carlo method. The computations indicate that the reversed injection allows for increasing the mass utilization efficiency of a standard feed configuration from 2-5% to a maximum of 20-30% depending on the initial efficiency.