Improvement of Plasma Distribution by Propellant Injection in Miniature Microwave Discharge Water Ion Thrusters

摘要

In order to improve thrust performance of a miniaturernmicrowave discharge water ion thruster, it is necessaryrnto increase plasma generation efficiency. In this study,rnwe have evaluated the plasma generation by changingrnpropellant injection position/direction using threedimensionalrnparticle simulations (PIC/MCC-DSMC).rnFrom downstream injection, neutral particle density isrnincreased in the discharge chamber. As results ofrnparticle simulations, the total ion number density isrnincreased, and moreover, the composition ratio of ionrnspecies (H_2O~+ and OH~+) contributing to the thrust isrnincreased. We have found that the propellant injectionrnfrom downstream provides the performancernimprovement for the water ion thrusters.