Research and Deveropement of a Sheath-Type Hall Thruster for Space Propulsion

1. 放电振荡现象的研究我们在1998年对线性霍尔推力器的研究中预测，要使鞘型霍尔推力器稳定运行，需要了解加速通道中的等离子体振荡，并对等离子体振荡引起的放电不稳定性进行补救。因此，我们使用线性霍尔推力器检查了振荡的原因。结果发现，主要的不稳定性是由于电离振荡。此外，基于离子和中性粒子动量方程的不稳定性分析推导出的解析预测与实验观测结果吻合得很好。这些结果在AIAA/ASME/SAE/ASEE联合推进会议上发表（AIAA论文98-3638），并发表在日本航空与空间科学学会学报上。护套式霍尔推进器的性能评价一套护套式霍尔推进器是在东京大学设计和制造的。阳极的设计避免了电离不稳定性：引入了空心阳极，它附着在加速区的上游。大约一半的总电离电流将在空心阳极内部产生。因此，我们能够很容易地找到稳定放电区域，尽管传统的加速电离区域非常小。从推力测量中可以看出，isps为1400秒，推力效率为25%。这些结果已在1999年国内学术研讨会上发表。通过考虑可伸缩性优化，性能将得到提高。

1. Research on Discharge Oscillation PhenomenaFrom our previous study on a linear-type Hall thruster conducted in 1998, it was predicted that understanding of plasma oscillations in an acceleration channel and remedy to the discharge-instability caused by the plasma oscillation would be required to obtain a stable operation in a sheath-type Hall thruster. Therefore, we examined the cause of oscillations using a linear-type Hall thruster. As a result, the main instability was found due to the ionization oscillation. Furthermore, the analytical prediction deduced from the instability analysis based on momentum equations of both ions and neutral particles have shown very good agreement 5 with the experimental observations. These results were presented at the AIAA/ASME/SAE/ASEE Joint Propulsion Conference (AIAA Paper 98-3638), and published on the Transactions of Japan Society for Aeronautical and Space Sciences.2. Performance evaluation of the sheath-type Hall thrusterA sheath-type Hall thruster has been designed and manufactured at the university of Tokyo. The anode has been designed to avoid the ionization instability : The hollow-type anode has been introduced, It was attached at the upstream of the acceleration region. About half of the total ionization current will be produced inside of the hollow anode. As a result, we were able to find the stable-discharge region easily, though the conventional acceleration-ionization region is very small. From the thrust measurements, Isp of 1400 sec and thrust efficiency of 25% have been marked. These results were presented at the domestic symposium in 1999. The performance will be improved by taking account of the scaling optimization.