Influence of internally mounted cathode location on discharge characteristics of Hall thrusters

Hall thrusters with internally mounted cathodes can achieve high efficiency, reduce plume divergence, and make plumes more uniform in the circumferential direction, all of which have promising applications. The electrons emitted by the internally mounted cathode are transported along the thruster axis by a strong magnetic field and are then coupled with ions in the plume region. The intensity of the magnetic field at the thruster axis varies sharply, and the cathode location is expected to affect the coupling process and thruster performance. Therefore, this study experimentally investigated this influence. Ion energy distributions and ion current density distributions were adopted to explain the influence of the cathode position on the coupling process and, thus, the discharge characteristics. It was observed that, if the cathode was close to the turning point of the axial magnetic field of the thruster, electrons emitted by the cathode easily moved toward the channel outlet, and the discharge efficiency could be increased by up to 1.3 %.