Control of Coherent Structures via External Drive of the Breathing Mode

Abstract: The Hall thruster exhibits two types of large-scale coherent structures: axially propagating breathing mode (m = 0) and azimuthal, with low m, typically m = 1, spoke mode. In our previous work, it was demonstrated that axial breathing mode can be controlled via the external modulations of the anode potential. Two regimes of the thruster response, linear and nonlinear, have been revealed depending on the modulation amplitude. In this work, using the high-speed camera images and developed image-processing technique, we have investigated the response of the azimuthal mode to the external modulations. We have found that, in linear regime, at low modulation voltages, axial and azimuthal structures coexist. At larger amplitudes, in the nonlinear regime, the azimuthal mode is suppressed, and only axial driven mode remains.