Electrical Facility Effects on Hall Current Thrusters: Electron Termination Pathway Manipulation

Abstract

A nonnegligible fraction of the charged particles in the Hall current thruster plume completes the electrical circuit through the conductive wall of a ground-based vacuum test facility. The resultant electrical circuit is different from the electrical circuit completed by the Hall current thruster in the onorbit environment. To understand the electrical circuit created in ground-based testing, this work examines the effect of an electrically biased metal plate, placed in the far-field plume of a Hall current thruster, on the plasma plume characteristics, the Hall current thruster thrust, and the electron termination pathways. An Aerojet Rocketdyne T-140 Hall current thruster is operated at 300 V and 10.3 A on xenon propellant. The operational neutral background pressure is , corrected for xenon. Two aluminum plates, one representative of the radial wall of the vacuum chamber and one representative of the axial wall of the vacuum chamber, are placed 2.3 m radially outward from the thruster centerline and 4.3 m axially downstream from the discharge channel exit plane, respectively. At each axial bias plate voltage, measurements of thrust, electrical characteristics of the Hall current thruster, thruster body electrical waveform, and radial–axial plate waveforms are recorded. A Langmuir probe, a Faraday probe, and an emissive probe are placed 1 m downstream of the Hall current thruster exit plane. The cathode-to-ground voltage and plasma potential behavior closely follow the trends observed from in-flight measurements of the Small Missions for Advanced Research in Technology-1 PPS-1350 Hall current thruster. This investigation experimentally quantifies the impact of the varying in-flight plasma plume conditions on Hall current thruster operation in a ground-based vacuum facility.