中文摘要：

以脉冲等离子体推力器（PPT）羽流为研究对象，基于单元粒子法和直接模拟蒙特卡罗法，建立三维物理模型，模拟羽流瞬态流动。假定电子等温流动将其动量方程简化并离散，运用交替隐式法求解等离子体电势。通过与实验数据和轴对称仿真结果对比验证仿真模型，分析流场中电势、浓度分布随时间变化情况。研究表明，本文所建模型能在平行和垂直于电极的两个平面内有效预测等离子体羽流参数，且仿真结果优于二维模拟。PPT羽流中推进剂返流质量份额极小。研究方法、结果对PPT羽流更深入研究具有参考价值。

英文摘要：

Here the research object was the plume of a pulsed plasma thruster （PPT） and a three dimensional physical model was developed to simulate the transient flow of plume based on particle-in-cell （PIC） and direct simulation Monte-Carlo （DSMC） hybrid method. The electron momentum equation was simplified and discreted with the assumption of isothermal electrons. Then the plasma potential was solved by an alternative iteration implicit scheme. The simulation model was verified by comparisons between the computational results and experimental data and existing two dimensional axi- symmetric simulation data. Then the profiles of potential and density versus time were analyzed. It is indicated that the model of this paper could effectively predict that parameters of the plasma plume in both parallel and perpendicular planes to electrodes. And the simulation results are better than those of a two dimensional model. Also the backflow mass fraction of propellant of PPT plume is very small. The method and results are referable for further study of PPT plume.