霍尔推力器等离子体磁鞘特性

Characteristics of magnetized sheath in Hall thruster

为进一步研究霍尔推力器壁面二次电子发射对发动机性能的影响,建立流体模型数值模拟了霍尔推力器磁化二次电子等离子体的鞘层特性,采用Sagdeev势的方法得到了鞘层的玻姆判据,以这个判据为鞘层边界条件数值讨论了磁场、二次电子发射以及不同等离子体对推力器等离子体鞘层结构的影响。结果表明,磁场和二次电子发射系数的增加都将使鞘层中粒子密度增加,鞘层电势升高,鞘层厚度减小;对于氩和氙二种等离子体,氙等离子体产生的鞘层势垒高,粒子密度大,鞘层厚度增加。这些结果直接影响推力器的电子传导机制及性能。

To investigate the effects of secondary electron emission on the performance of engine,a liquid model has been used to study the characteristics of the magnetized plasma sheath.And the Bohm criterion of the plasma sheath was given out by using the Sagdeev potential method.Then the effects of magnetic field,secondary electron emission and plasma species on the structure of plasma sheath in Hall thruster were discussed by using the Bohm criterion as the boundary conditions.The simulation results indicate that both particle density and sheath potential increase with the augment of secondary electron emission coefficient and the azimuth angle of magnetic field which changes the sheath thickness.Meanwhile,both sheath thickness and wall potential vary in different plasma species.These effects will influence the wall material and the performance of thruster directly.