Optimization of discharge parameters in an inductive RF ion thruster prototype

Abstract

This paper presents the results of an experimental study of inductive RF ion thruster prototype parameters, which have demonstrated a strong dependence of the prototype characteristics on the length of the gas-discharge chamber and the operational frequency of the RF generator. The best result was obtained when the prototype was operated at a frequency of 4 MHz with a gas-discharge chamber 5 cm long. The experiments demonstrated that there is a significant resource for improving thruster parameters associated with an increase in the fraction of the RF power absorbed by the plasma. The latter can be achieved by superimposing an external magnetic field on the discharge. In parallel with the results of the experiments, this paper presents numerical calculations based on the model taking into account the presence of a parasitic capacitive channel of the RF power input into the discharge, as well as power losses in the external circuit. Calculations have shown that the experimentally observed effects are associated with the effect of the capacitive RF power input channel, as well as the frequency dependence of the plasma's ability to absorb the RF power.