Spectral dependency of pulsed GHz electromagnetic emission from Hall thrusters on discharge current oscillations

Radiation emitted from Hall thrusters in the GHz range has been observed to occur as short pulses. The origin of this emission is still unclear and raises questions of both physical understanding and electromagnetic compatibility between the thruster and the spacecraft. In this work, experimental investigations of a connection between the pulses appearance and characteristics, and low frequency oscillations of the discharge, are performed. They provide the first evidence for the existence of such a connection, especially on a spectral level. A dependency of both the pulses appearance and spectral components on the phase of breathing mode oscillations is shown. These spectral components also appear as essentially uncorrelated to the resonant frequencies of the metallic vacuum chamber. The observed spectral dependence with low-frequency oscillations of the discharge, in particular, is expected to give valuable insight into the physical mechanisms at the root of this emission.