Preliminary Measurements of Time-Resolved Ion Velocity Distributions Near a Hollow Cathode

Presented are preliminary measurements of near-cathode ion velocity distributions using time-resolved laser induced fluorescence. Two experiments were performed. First, time-averaged velocity distributions were measured in a LaB6 hollow cathode plume under the influence of a Hall thruster magnetic field provided by the 6-kW H6 thruster. The discharge was sustained without a downstream anode but rather using the cathode’s heater and keeper. Time-averaged velocity distributions were measured at several axial positions downstream from the cathode. Additionally, the ion velocity distribution was measured at the cathode exit without the magnetic field. The second experiment measured time-resolved ion velocity distributions. Operating the cathode in a similar manner, the measurements were made at the cathode exit under nominal and high magnetic field conditions. Lastly, a time-resolved velocity distribution was measured at the cathode exit in the full Hall thruster discharge under nominal magnetic field conditions.