1 Remote Diagnostic Measurements of Hall Thruster Plumes

This paper describes measurements of Hall thruster plumes that characterize ion energy distributions and charge state fractions using remotely located plasma diagnostics. Plume measurements were performed using electrostatic analyzers (ESAs) and ExB probes from Plasma Controls, LLC on ion and plasma sources at Colorado State University (CSU) and Hall thrusters operated at the Air Force Institute of Technology (AFIT) and the Air Force Research Laboratory (AFRL). Data are presented from ion source testing at CSU that demonstrated the performance of ESA and ExB probes to characterize energy and charge state. Next, energy and charge state measurements are described from testing of a 200 W Hall thruster at AFIT. Measurements showed variation in the ion energy distribution with changes in thruster power and an increase in the fractions of multiply charged ions with increasing azimuthal position. Finally, ExB probe charge state measurements are presented from a 6 kW class laboratory Hall thruster operated at low discharge voltage levels at AFRL/RZSS. Like the 200 W Hall thruster measurements at AFIT, results from the 6 kW Hall thruster showed an increase in the fractions of multiply charged ions with increasin