Driving low frequency oscillations in a Hall thruster

Abstract

Coherently rotating azimuthal and axial breathing modes in a cylindrical Hall thruster can be driven using a segmented anode in appropriate thruster regimes. To drive the azimuthal mode, a sine-wave bias with the varying amplitude of 5–50 V is applied to four anode segments. The bias voltage between segments is phase shifted. The breathing mode is driven by applying sine-wave to the anode segments without phase shift. A fast camera is used to monitor global fluctuations in the plasma. Planar Langmuir probes, emissive probes and laser-induced fluorescence are used to obtain time-averaged and time-dependent plasma parameters. The effect of the driven spoke and breathing oscillations on the thruster performance in terms of the plasma plume characteristics (propellant utilization, current utilization, energy utilization and ion energy distribution function) and a comparison between naturally occurring and driven oscillations as well as their dependence on the magnetic field will be discussed in this paper.