700W功率HET-80霍尔推力器束流特性研究

Beam Characteristics of HET-80 Hall Thruster with 700 Watts

霍尔推力器的束流特性能够体现推力器的工作状态,为了了解额定功率1350W的Hall Effect Thruster-80(HET-80)霍尔推力器在700W功率下的工作状态,研究设计了一套等离子体诊断系统,包括了法拉第探针、平面型Langmuir单探针、阻滞能量分析仪(RPA)和发射光谱,对HET-80霍尔推力器在700W功率下的束流特性进行了诊断实验。实验结果显示:700W功率工况下HET-80霍尔推力器束流发散半角为45°,整体呈现出纺锤形分布,束流中心区域的离子电流密度分布呈现出圆环型霍尔推力器典型的双峰结构;由于等离子体的复合碰撞导致离子量变少,实验中法拉第探针测量得到的积分电流随着轴向距离增加而减小;在束流区边缘发生了较多的CEX碰撞,使该区域电子温度骤升;中心区离子能量接近247e V,相较于推力器放电电压310V,评估霍尔推力器加速效率达79.6%,加速效率较好,整体束流结果表明HET-80霍尔推力器在700W功率工况下表现正常。实验中发现法拉第探针结合RPA测量出来的离子数密度较Langmuir探针测量出的离子数密度更为准确;由于霍尔推力器只有一个空心阴极,发射光谱得到的出口附近电子温度和离子原子相对浓度分布均为空间非均匀状态。

A serious plasma diagnostic apparatus are designed to get a deep understanding of the working state of a 700 watts power Hall Effect Thruster-80（HET-80,rated power is 1350 W）. These plasma diagnostic apparatus include Faraday probe,planar Langmuir probe,Retarding Potential Analyzer（short for RPA）and Emission spectrum. The experimental results show that the half divergence angle of this thruster is 45°,and the whole divergence area is similar to the shape of spindle. The ion current density distribution in the center of the beam presents a typical bimodal structure of the ring-type Hall thruster. Due to the plasma composite collision decreasing the ion content,the integrated current decreases with the increase of the axial distance. Furthermore,the Charge Exchange collision（short for CEX）leads to the electron temperature significantly increased at the edge of the beam region. The central ion energy is close to 247 e V,and the acceleration efficiency of the Hall thruster is 79.6% with respect to the discharge voltage of 310 V. This acceleration efficiency shows a good performance of the thruster. The results above show that the HET-80 Hall thruster behaves normally at 700 W. It was also found that the ion density measured by Faraday probe combined with RPA was more accurate than the results measured by Langmuir probe. Since there is only one hollow cathode in the Hall thruster,emission spectrum shows that the distribution of electron temperature and the relative concentration of ions and atoms near the outlet is non-uniformity distributed.