稳态等离子体推进器羽流场数值模拟

Numerical simulation of stationary plasma thruster plume

采用二维轴对称模型,使用粒子网格法(PIC)和直接模拟蒙特卡洛法(DSMC)相结合的方法,对稳态等离子体推进器(SPT)羽流场进行了数值模拟.采用DSMC方法中的随机取样频率法(RSF)求解粒子碰撞过程,并对比了不同的分配电荷方式、电子运动模型及SPT出口条件时的羽流场.将不同条件计算得到的羽流场中距SPT出口0.1m,0.5m及1.0m处的离子电流密度和电荷密度与实验结果进行了对比,得出在采用面积权重法分配电荷、等熵模型描述电子运动和用实验值设定发动机出口参数时对SPT羽流场数值模拟的电流密度和轴向附近的电荷密度结果与实验结果符合程度较好的结论.

Using 2D axisymmetrical model, a hybrid particle-fluid model was used to model plasma dynamics of the stationary plasma thruster （SPT） plume, which includes the particle in cell （PIC） method and the direct simulation Monte Carlo （DSMC） method. The randomly sampled frequency （RSF） method was applied to solving the collision process between the atoms and the ions. Three different computational conditions were contrasted, which are ways of charge assignment, models of electron moving and setting of the SPT outlet parameters. The ion current density and the ion density of the computations were compared with these of the experiments results at 0.1 m, 0.5 m and 1.0 m to the SPT exit. The present result shows that the computations, including the ion density near the thruster axis and the ion current density, satisfactorily agree with the experiments by charge assignment for linear weighting in 2D, electron moving for constant entropy model, and setting outlet parameters of the thruster by experiments.