Study of low-frequency oscillations in a double-stage Hall thruster

The characteristics of low-frequency oscillations of double-stage Hall thrusters are quite different from those of conventional single-stage Hall thrusters. In this paper, the effects of double-stage discharge on the low-frequency oscillations are experimentally investigated. The results indicate that the amplitude significantly decreases with increasing magnetic field strength and voltage during the ionization stage. Meanwhile, data analysis reveals that ionization occurs in both stages and that the transport ion current between the two stages is the key factor that affects the amplitude and main frequency of the oscillations. Two new processes, namely the ion transport and ion recombination caused by double-stage discharge, are found to be relevant to the change in the current oscillations. To summarize, the ionization stage relieves the oscillations in the acceleration stage, leading to a reduction in the amplitude of the discharge current.