离子推力器放电腔数值模拟

Numerical simulation of ion thruster discharge chamber

为更好地理解放电腔内等离子体物理机制,对Kaufman型离子推力器放电腔进行了数值研究,其中初始电子采用粒子模拟的方法处理,二次电子和离子采用漂移-扩散流体近似描述。模拟结果与已有实验测量数据进行对比表明:所采用计算方法适用于放电腔内等离子体流动规律的数值研究;模拟得到的稳态下等离子体分布及变化规律与实验测量数据相吻合;磁场的设计对初始电子起到显著的约束作用,有效地提高了其与工质气体的电离碰撞几率;二次电子的精确描述还需在流体方程中耦合磁场效应。

For better understanding of the plasma physical mechanism in the discharge chamber, the discharge chamber of Kaufman ion thruster was researched numerically, the primary electrons are treated as particles and the secondary electrons and ions are described with drift-diffusion model. The numerical results are compared with the given experimental data, showing that: the computational method suits the numerical research of the plasma flow rules in the discharge chamber; the plasma flow distribution and evolvement rule are obtained in the steady state, which agree with the experimental measurements; primary electrons are restricted distinctly by the design of magnetic field, of which the probability of ionization collision with propellant gas is increased effectively; precise description of secondary electrons needs to couple the effect of magnetic field in the fluid equations.