Study on the influence of change in axial position of cathode on the ignition process of a Hall thruster

Abstract

A hollow cathode is an important component of the discharge circuit in Hall thruster. Different axial positions of the hollow cathode will cause the electrons emitted by the cathode to enter the discharge channel differently, thereby affecting the energy acquisition of the electrons and influencing the ignition of Hall thruster. Thus, a high-speed camera with a charge-coupled device was used to examine the plume features over time when the cathode was located at different axial positions. To better understand the changes in the plasma parameters in the discharge channel and plume during ignition, a two-dimensional axisymmetric fully kinetic particle-in-cell/Monte Carlo collision model was used to calculate the ion density and potential distribution at different times during the ignition process of Hall thruster. The results indicate that the ion density generated in the initial stage of ignition is larger at the exit of the discharge channel when the cathode axial position is close to the exit of the discharge channel. The electron avalanche ionization occurs earlier, and the peak value of the ignition pulse current is larger. These differences may occur because the energies of the electrons (emitted by the cathode) entering the discharge channel from different cathode axial positions differ.