Simulation of discharge process of Hall thruster under the internal and external cathode conditions

Abstract

Hall thruster has been used widely in orbit correction and station-keeping of geostationary satellites for the advantage of high specific impulse, long life, and high reliability. The cathode is an important part of Hall thruster, which can neutralize ion beam and provide electrons to the thruster for ionization. At present, the position of cathode can be divided into two kinds: internal cathode and external cathode. And the discharge parameters under the two different cathode positions is very different, such as the coupling voltage and the ion density. And this paper considers the mechanism of influence of the cathode position on the discharge process of Hall thruster, the discharge process of Hall thruster under internal and external cathode conditions was simulated by PIC-MCC simulation method. The simulation results show that the electron conduction near the thruster outlet is relatively strong under the internal cathode condition. The trajectory of electrons emitted from the cathode position under the two conditions is further simulated. The simulation results show that the electrons will be bound by the magnetic field and form a virtual cathode when they enter the simulation area. The lower coupling voltage under the internal cathode condition is explained by comparing the positions of virtual cathode. At the same time, some electrons emitted from the internal cathode position can quickly reach the main beam region. The ion density distribution is also compared. The ionization regions of Xe+, Xe2+ and Xe3+ ions are relatively outside under the internal cathode condition, and the peak densities of Xe2+ and Xe3+ ions are relatively low. Compared with the experimental results, it is shown that the electron trajectory in the plume region has a significant effect on the plume shape.