Spacecraft interaction test results of the high performance hall system SPT-140
Ground rests were performed to help characterize modes of interaction between the SPT-140 Hall thruster and spacecraft components. The experiments were performed at NASA Glenn Research Center and at the University of Michigan. Measurements were made of thruster plume current density, electromagnetic interference (EMI), and surface sputtering and contamination. Diagnostics included Faraday probes, collimated sputter/deposition targets, and radio-frequency detectors. Ion current density measurements showed exponential decay with off-axis angle up to approximately 30 degrees. At off-axis angles greater than 30 degrees, results varied with chamber background pressure, presumably due to ambient charge exchange plasma. Sputter rates of solar cell coverglass. Kapton, and RTV were accurately measured 1 m from the thruster exit for off-axis angles less than 60 degrees. At off-axis angles greater than 60 degrees, the sputter rate was on the order of the measurement uncertainty. EMI tests found very little emission in the traditional RF communication bands. At the lowest frequencies, one band of E-field emission (10 kHz to 20 MHz) was detected which exceeded the MIL-STD-461C specification by up to 53 dB.
