低功率平面型霍尔推力器的工作特性研究

Operating characterization of low power planar Hall thruster

关键词:  霍尔推力器  点火  阳极效率  负梯度磁场  羽流发散

Key words:  Hall thruster  Ignition  Anode efficiency  Negative gradient magnetic field  Plume divergence

摘要:

为了解决低功率霍尔推力器存在的寿命问题，本文设计了一种平面型霍尔推力器。该推力器取消了内部放电通道，前壁和阳极在同一平面，电离和加速过程完全发生在推力器外部的开放空间中。推力器在0.6~1.0 mg/s的氙气流量下，实现稳定放电。本文实验研究了不同运行参数下推力器的阳极电流特性、推力特性和羽流束流特性。结果表明，阳极电流的振荡频谱主要集中在20~60 kHz，与常规霍尔推力器的呼吸振荡频率范围相似。在62~245 W的功率下，推力为3.2~10.5 mN，阳极效率为8%~22%。推力水平与同功率等级的传统霍尔推力器相当，而阳极效率偏低。利用法拉第探针获得离子的束流特性，结果表明：较低的羽流发散效率是造成目前推力器阳极效率偏低的主要因素。结合实验结果，分析了平面型霍尔推力器与传统霍尔推力器在离子加速方面的差异。本文设计的平面型霍尔推力器为解决霍尔推力器的壁面侵蚀问题提出了一种可能的方案。

Abstract:

In order to extend the life time of low power Hall thrusters， a planar Hall thruster is proposed in this paper. This design eliminates the internal discharge channel. The front wall and the front surface of the anode are in the same plane， therefore the ionization and acceleration process completely occur outside the thruster. The thruster achieves stable discharge at the xenon flow rate of 0.6~1.0 mg/s. The characteristics of anode current， thrust， and plume beam under different operating parameters were experimentally studied. The oscillation frequency spectrum of anode current is mainly concentrated from 20 to 60 kHz， which is similar to that of conventional Hall thrusters. At the power level from 62 to 245 W， the thrust and the anode efficiency are separately in the range of 3.2~10.5 mN and 8%~22%. The thrust level is close to the traditional Hall thruster with the same power level， but the anode efficiency is lower. The measurement results of the ion beam characteristics with Faraday probe show that the low plume divergence efficiency is the main reason for the low anode efficiency. Based on the experimental results， the differences between the operation mechanism of the planar Hall thruster and the traditional Hall thruster are analyzed. The planar Hall thruster designed in this study proposes a possible solution to the wall erosion problem of the Hall thruster.