Effects of Background Pressure on SPT-140 Hall Thruster Performance
John Steven Snyder, Giovanni Lenguito, Jason D. Frieman, Thomas Haag, Jon Mackey
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.