为进一步研究霍尔推进器壁面二次电子发射对推进器性能的影响,采用流体模型数值模拟了二次电子磁化效应的等离子体鞘层特性.得到二次电子磁化鞘层的玻姆判据.讨论了不同的磁场强度和方向、二次电子发射系数以及不同种类等离子体推进器的鞘层结构.结果表明:随器壁二次电子发射系数的增大,鞘层中粒子密度增加,器壁电势升高,鞘层厚度减小;鞘层电势及粒子密度随着磁场强度和方位角的增加而增加;而对于不同种类的等离子体,壁面电势和鞘层厚度也不同.这为霍尔推进器的磁安特性实验提供了理论解释.
In order to investigate the effects of the inner wall secondary electron emission on the performance of Hall thruster,a hydrodynamic model is used to study the characteristics of plasma sheath considering secondary electron magnetization.The Bohm criterion of the magnetized plasma sheath is obtained.The structures of plasma sheath in Hall thruster with different magnetic field magnitudes and directions,different secondary electron emission coefficients and different plasma species are discussed.Simulation results indicate that both particle density and wall potential increase while the sheath thickness decreases with the augment of secondary electron emission coefficient.The sheath potential and the particle density increase with the magnitude and azimuth angle of magnetic field increasing.Both the sheath thickness and the wall potential are different in different plasma species.These research results provide a theoretical explanation for the magnetism-ampere characteristic of the Hall thruster.