Validating A Plasma Momentum Flux Sensor Against an Inverted Pendulum Thrust Stand

Abstract

The accuracy of a plasma impact force sensor was compared to that of the more commonly used inverted pendulum thrust stand using a 5 kW Xe Hall thruster. A plasma momentum flux sensor (PMFS) was designed and constructed based on a previous NASA-Marshall Space Flight Center (MSFC) design. Real-time force measurements were made with both the PMFS and the inverted pendulum thrust stand. The PMFS measured the force exerted onto it from the Hall thruster exhaust plume with a resolution of 0.1 mN, and an average accuracy better than 98% compared to the thrust stand. Experiments were completed at the Large Vacuum Test Facility (LVTF) at the University of Michigan. The total force from the Hall thruster was modulated from 34 mN to 356 mN by varying both the anode voltage, from 150 V to 500 V, and the neutral Xe gas flow rate from 5 mg/s to 15 mg/s. The majority of the force data taken during the experiment campaign was completed as a "blind study" where force measurements from both techniques were disclosed only after the experiment was completed.