Predicting Electron Transport Using Simulated Axial Waves in a Radial- Axial Hybrid Hall Thruster Model

摘要

Axial waves predicted by a two-dimensional hybrid numerical model have been used to estimate electron cross field transport due to tilted waves with azimuthal components. Since the radial-axial hybrid simulation cannot model these tilted waves directly, the predicted axial waves are assumed to couple symmetrically into two counter-propagating axial-azimuthal waves. A linearized two-dimensional dispersion relation is solved to obtain the azimuthal component of wavenumber consistent with the frequency and axial wavenumbers predicted by the radial-axial simulation. The resulting transport profiles are in qualitative agreement with experimental measurements of electron mobility when the power levels of the fluctuations approach saturation levels. For large amplitude fluctuations, the predicted electron mobility profile exhibits a transport barrier near the exit plane of the thruster consistent with experimental measurements, suggesting that this barrier may be due to a transition from transport-enhancing azimuthal waves to transport- limiting axial waves in this region.