Ultrahigh-Speed Imaging of Hall-Thruster Discharge Oscillations With Krypton Propellant

The discharge oscillations of a 200-W Hall thruster, with krypton propellant, was captured optically with an ultrahigh-speed camera providing information up to 500 kHz. The sequential images provide a temporal 2-D description of the plasma field, which illustrate the direct emission (i.e., visible light emitted by the plasma discharge) of the plasma increasing and decreasing within the thruster channel. These periodic fluctuations of intensity have a frequency of 31 kHz, which is 10% less than the measured breathing-mode frequency utilizing xenon propellant under the same conditions.