Effect of double-stage discharge on the performance of a multi-mode Hall thruster

•Double stage discharge on performance of a multi-mode Hall thruster is studied.•Ionization process can be optimized at a wide range in a double stage thruster.•The effect of ionization stage discharge on performance is explained.•The effect of discharge parameters on ionization distribution is given.•The positive effect of non-emissive anodes on double stage Hall thruster is confirmed.

In order to develop multi-mode thrusters for all-electric propulsion spacecraft, a double-stage Hall thruster is designed and investigated experimentally. By applying two independent non-emissive electrodes and a double-peaked magnetic field in the double-stage Hall thruster, the propellant can be ionized in the first stage and then accelerated in the second stage. Experiment results revealed that double-stage discharge effectively improves thruster performance in high specific impulse working mode by reducing the electron current. A one-dimensional model is used to discuss the effects of discharge parameters on ionization distribution theoretically. As a conclusion, ionization distribution (in terms of position and length) in high specific impulse mode (mode I) is significantly different compared to high-thrust working mode (mode F). This double-stage Hall thruster provides a double-stage discharge in mode I to enhance the ionization in the channel and a single-stage discharge in mode F to reduce the ion wall-loss, achieving high efficiency in both working modes.