Time-Averaged and Oscillatory Characterization of a Hall Plasma Discharge

We characterize a 70 mm diameter stationary plasma thruster operating on xenon at 200-500 W using nonintrusive laser measurements. This study resolves both time-averaged properties and oscillatory phenomena in the plasma discharge. Specifically, we explore how the plume ion velocity field evolves in time with respect to periodic discharge current oscillations using time-synchronized laser induced fluorescence (LIF) techniques. In this LIF scheme, a triggered signal acquisition gate is locked at a given phase of the current oscillation period, allowing for drift in the oscillation. The laser is modulated at a characteristic frequency and the induced fluorescence signal is extracted out of the bright background emission using homodyne detection with a lock-in amplifier.