电子温度各向异性对霍尔推力器BN绝缘壁面鞘层特性的影响

建立多价态多组分等离子体一维流体鞘层模型,引入电子温度各向异性系数并考虑出射电子速度分布,研究了电子温度各向异性对霍尔推力器中的BN绝缘壁面鞘层特性和近壁电子流的影响.分析结果表明,相比于纯一价氙等离子体鞘层参数,推力器中的多价态氙等离子体鞘层电势降略有降低,电子壁面损失增加,临界二次电子发射系数减小.推力器中的电子温度各向异性现象可以显著地加大出射电子能量系数,进而降低鞘层电势降,增强电子壁面相互作用.数值结果表明,空间电荷饱和机制下电子温度各向异性对鞘层空间电势分布影响显著. 关键词： 霍尔推力器 电子温度各向异性 空间电荷饱和鞘层

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.