Gas inlet impact on neutral density and recycle pattern with a disk shaped antenna in a miniature ion thruster through particle simulation

Ali Yousefian

doi:10.1063/5.0067742

Abstract

The gas inlet configuration has a direct impact on the neutral density pattern within a miniature ion thruster. We aimed to investigate the impact the gas inlet configuration and neutral density pattern will have on the neutral recycle rate within a miniature ion thruster utilizing a disk shaped antenna. Four inlet configurations were considered for this study, and 3D electromagnetic particle-in-cell simulation was utilized to simulate the plasma inside the discharge chamber. The simulation results indicate a clear shift in neutral density toward the inlet, with the single horizontal inlet configuration having a 45% increase in neutral density in the vicinity of the inlet walls. The neutral recycle rate also experienced a clear shift toward the inlet walls, with the single bottom inlet configuration experiencing a 23% increase in the rate of ion loss near the inlet wall and a similar 22% increase for the single horizontal inlet while the four smaller inlets had a similar rate of neutral recycling throughout. These results are a novelty in this field as they clearly indicate the impact gas inlet and neutral density have on the miniature ion thruster’s performance and open a new area of research to further optimize the gas inlet configuration for miniature ion thrusters.

Highlights

An ion thruster is an electric propulsion system that works by ionizing the neutral particles inside the discharge chamber through high energy collisions with electrons and accelerating the resultant positive ions outside the engine by using electrostatic fields resulting in thrust
We aimed to investigate the impact of neutral density distribution on the miniature ion thruster performance in the form of the neutral recycle rate phenomena using a symmetrical disk shaped antenna
Our results show a significant impact on the neutral density distribution within the discharge chamber, favoring the inlet position in the single inlet configurations, with a 45% increase in neutral density for the single horizontal inlet case while the four inlet cases have led to more uniform neutral density distribution as expected

Summary

Introduction

An ion thruster is an electric propulsion system that works by ionizing the neutral particles inside the discharge chamber through high energy collisions with electrons and accelerating the resultant positive ions outside the engine by using electrostatic fields resulting in thrust. Numerical simulations are an invaluable tool for analyzing miniature ion thrusters mainly due the fact that experimental setups offer a limited view into their performance (mainly because of their small size) and are costly. Most works in this field focus on the behavior of electrons with respect to microwave propagation and engine design.. In the works that followed, Hagelaar et al. expanded on that simulation to analyze the impact of the magnetic field on thruster performance While these works and others do focus on plasma wall interactions to varying degrees, their limit lies in the fact that neutrals were either not included or treated as background particles. A comprehensive study of the impact of neutral recycling phenomena on performance as well as neutral density has not been carried out, the motivation for our work

Objectives

Methods

Conclusion