Power dependence of the electron anomalous collision frequency in a Hall thruster

摘要

The profile of the electron anomalous collision frequency is estimated in a 4.5 kW commercial Hall thruster as a function of discharge power. Internal measurements of plasma potential and electron temperature are made in the thruster channel with a high-speed translating probe over a range of throttling conditions from ISO - 400 V and 0.6 - 4.5 kW. The Hall2De code is used in conjunction with these internal plasma parameters to estimate the spatial dependence of the anomalous collision frequency at fixed voltage, 300 V, and three power levels. It is found that the anomalous collision frequency is smaller than the classical collision frequency upstream of the location of the magnetic field peak but that the magnitude of anomalous collision frequency is dominant downstream of this location. The variation of the collision frequency is analyzed as a function of operating power, and these results are discussed in the context of developing a phenomenological model for how this parameter depends on thruster operating conditions.