磁屏蔽霍尔推力器磁极腐蚀数值模拟研究

Numerical Simulation on Pole Erosion in a Magnetically Shielded Hall Thruster

关键词:  磁屏蔽  霍尔推力器  数值模拟  磁极腐蚀  离子电流密度

Key words:  Magnetic shielding  Hall thruster  Numerical simulation  Pole erosion  Ion current density

摘要:

磁极腐蚀问题成为磁屏蔽霍尔推力器的主要寿命失效模式。为了研究磁极腐蚀的机理，本文基于粒子网格方法建立推力器放电的数值仿真模型，结合溅射模型模拟磁极腐蚀现象，统计磁极表面收集的入射离子运动状态，获取磁极腐蚀特性，据此探究磁极腐蚀的机理以及影响磁极腐蚀速率的因素。结果表明：磁屏蔽霍尔推力器出口倒角附近形成的高原子密度区同时也是径向电场占主导的区域，在此处电离产生的低速离子易于径向发散进而偏转向磁极方向运动。磁极表面腐蚀现象呈现径向分布不均的特点，内磁极附近轴对称电场对离子的作用是导致磁极中心腐蚀速率远高于其他位置的主要原因。

Abstract:

The problem of pole erosion becomes the main ineffective mode of lifetime for magnetic shielding Hall thruster. In order to study the mechanisms of the pole erosion， a numerical model of thruster discharge process was established based on particle-in-cell method. Combining with the sputtering model， the erosion phenomenon was simulated. Statistics on the motion of the collected ions sputtering on the poles could provide pole erosion characteristics. Then the erosion mechanisms and the influential factors on the pole erosion rate were analyzed. The numerical results show that in the region of high neutral density near the channel exit chamfer， the radial electric field dominates， where newborn ions at low velocity tend to diverge radially and move to the poles. The poles are unevenly eroded and the erosion rate at the center of the inner pole is much higher than the other radial positions due to the ions in confinement of the axisymmetric electric field in the vicinity of the inner pole.