Investigation of Improved Hall Thruster Configurations for Low-Power Operation

This paper deals with the performance degradation of Hall thruster, when it is operated at reduced power levels of 200-300 W. The standard approach to overcome the ionization efficiency problem by scaling down the thruster is limited by the magnetic material and circuit properties. In order to improve the thrust-measurement accuracy, a new calibration system was designed and built. Results indicate that, in the 200-350-W input power range, higher thrust, specific impulse, and efficiency are achieved. The effect of the magnetic-field distribution on the thruster performance was also examined and included a preliminary investigation of a novel idea of a new type of Hall thruster, which uses a reversed magnetic field near the anode. In order to implement a reversed magnetic-field configuration, a modified magnetic circuit was built and tested. Preliminary results demonstrated that indeed this configuration operated as a thruster, although at somewhat lower thrust levels. On the other hand, plume measurements indicate for a better focusing of the jet with this configuration.