Effect of electron temperature anisotropy on BN dielectric wall sheath characteristics in Hall thrusters

The effect of electron temperature anisotropy on BN dielectric wall sheath characteristics in Hall thruster plasma is studied by using a one-dimensional fluid sheath model with the help of emitted electron velocity distribution and multi-species mixed ion effects. Analytic results show that, in comparison with that of a pure univalent xenon plasma, the sheath potential drop and the critical secondary electron emission coefficient are decreased in mixed valence xenon plasmas, while the primary electron flux at the wall is increased. The electron temperature anisotropy in Hall thrusters thus significantly enhances the electron energy emission coefficient, and further reduces the sheath potential drop while intensifies the electron-wall interaction. Numerical results also indicate that the electron temperature anisotropy influences the potential distribution of space charge saturated sheath remarkably.