Coupling operation characterization of the Hall micro thruster with a thermal emission cathode with a grid

Abstract

The coupled operation characteristics of micro-electric thrusters and cathodes are significant research topics. However, there is a lack of studies focusing on the coupled operation of micro-electric thrusters and micro-cathodes, particularly those operating at currents below ten milliamperes. Therefore, this research presents a watt-class Hall micro thruster (HMT) and a thermal emission cathode with a grid (TECG) to investigate the coupling operation characteristics. This research demonstrates the results of the coupling potential, plasma parameters, and thrust performance of the propulsion system under diode and triode modes and indicates that the comprehensive operation characteristics of the HMT become better under the triode mode. Notably, the cathode floating and space plasma potential are significantly reduced as the grid voltage increases. However, ionization and thrust performance vary non-monotonically with grid voltage, exhibiting an inflection voltage and reaching their maximum near this inflection voltage. We analyzed the anomalous variation behavior after completing the experiments and validation work. The analysis results suggest that this behavior may be related to the unique magnetic flux lines distribution within the near-emitter region due to the special topological relation between TECG and HMT. We also provide what we believe to be the optimal grid voltages for various operating environments.