Simple model for cathode coupling voltage versus background pressure in a hall thruster
A simple model is developed to capture the effect of background pressure on the cathode coupling voltage in a Hall effect thruster. Only the voltage drop from the thruster plume to the cathode exit plane is considered as the voltage drop inside the cathode is considered to be insensitive to background pressure effects. The underlying hypothesis of this investigation is that this voltage drop is the result of anomalously high-resistivity, driven by ion acoustic turbulence, that onsets in the plume of the hollow cathode. A one-dimensional model is presented for how the growth of this mode drives the potential drop, and how, in turn this voltage drop depends on neutral density pressure in the plume. This model is compared to experimental data from the SPT-100 Hall thruster and the fit parameters of the model are in agreement, within uncertainty, of theoretical and experimental values. Results show agreement with experimental data and theoretical calculations for the SPT-100 Hall thruster.
