Experimental Investigation of a Direct-Drive Hall Thruster and Solar Array System

Abstract

Studies of high-power solar electric propulsion systems (i.e., tens to hundreds of kilowatts) suggest that significant mass savings may be realized by implementing direct-drive power systems. The National Direct-Drive Testbed was established to address issues associated with implementation of direct drive, and experimental results at power levels up to 10 kW are reported here. Hall thruster operation and control were shown to be simple and no different from that for operation on conventional power supplies. Thruster oscillations were the same as those for conventional power supplies, did not adversely affect solar array operation, and were independent of filter capacitance from 8 to . Solar array current and voltage oscillations were very small compared to their mean values and showed a modest dependence on capacitor size. Significantly, no instabilities or anomalous behavior were observed in the thruster or power system at any operating condition investigated, including near and at the array peak power point. Thruster startup using the anode propellant flow as the power “switch” was shown to be simple and reliable, with system transients mitigated by the proper selection of filter capacitance size. A simple electrical circuit model was developed and is shown to have good agreement with the experimental data.