Effects of Background Pressure on SPT-140 Hall Thruster Performance

Abstract

The performance of many Hall thrusters has been shown to exhibit sensitivity to background pressure in ground-based test facilities, and this property can have an impact on the prediction of in-space performance. The SPT-140 Hall thruster, similar in design to the SPT-100 thruster, which shows such sensitivity, was subjected to a series of tests to characterize the effects of background pressure on thruster performance over a discharge power range of 0.9–4.5 kW. Thrust sensitivity to pressure, in an absolute sense, was largest at 4.5 kW and decreased with power until there was little-to-no measurable effect at 0.9 kW. In a relative sense, thrust sensitivity was similar at all powers above 0.9 kW with about 2–4% higher thrust measured at than at the lowest operating pressure. Thruster magnetic field sensitivity, examined as a function of magnet current, did not have a strong dependence on facility pressure.