Particle simulation of discharge current oscillation in Hall thrusters

Twenty kHz-range discharge current oscillation with a large amplitude is observed in Hall thrusters, causing unstable operation. In our previous studies, the effects of the anode orifice configuration on the current oscillation have been investigated. Using the results of neutral particle simulations, the relationship between the neutral distribution and the propellant inlet condition was analyzed. In the present study, to confirm the effect of the neutral distribution and investigate the ionization process in detail, axisymmetric analysis in the acceleration channel was carried out using a hybrid-PIC code. As a result, the periodic ionization and current oscillation were obtained. The oscillation amplitude for a smaller orifice is greater due to the higher ionization rate. The results agree with the effect of the neutral distribution predicted by the simulations.