Obtaining plasma potential measurements in Hall thruster plumes

Summary form only given. Plasma potential measurements in electric propulsion systems are necessary for complete performance evaluations. There have been several measurement methods proposed in the past without a clear indication of which method is the most accurate. An investigation was performed to compare a number of these methods. The techniques employed here include two different emissive probe methods and a procedure that involves the analysis of the electron energy distribution function. Near- and far-field measurements were taken in the plumes of a stationary plasma thruster and an anode layer thruster. The techniques employed are explained, and an analysis of the measurements are discussed.