Two-Axis Laser-Induced Fluorescence of Singly-Charged Xenon inside a 6-kW Hall Thruster

Abstract

We present two-axis laser-induced fluorescence velocimetry measurements of the 5d[4]7/2 → 6p[3]5/2 transition for singly-charged xenon (Xe II) at 834.953 nm (vacuum) inside a 6kW Hall thruster. The spatial density of the data is higher near the wall than in the center of the channel to better capture the dynamics of the ions believed to be responsible for wall erosion. The thruster has a nominal operating discharge voltage of 300 V and anode mass flow rate of 20 mg/s and has been operated for ~330 hours prior to testing. It is operated under seven conditions spanning discharge voltages of 150-600 V and anode mass flow rates of 10-30 mg/s. The bulk velocity of the near-wall ion populations varies from 0.5 to 25 km/s with an angle of incidence relative to the normal of the wall surface that varies from roughly 45 to 80 degrees. In general, the bulk velocity and angle of incidence is strongly correlated with the discharge voltage and weakly correlated with the anode mass flow rate. There is strong correlation between the axial locations where high energy (greater than few tens of eV) ions exist and where erosion is discernable in the channel profile.