小型感性耦合射频等离子体中和器的实验研究 *

Experimental Studyofa Mini Inductively Coupled Radio-Frequency Plasma Neutralizer

关键词:  感性耦合等离子体  中和器  离子推力器  空心阴极  电子源

Key words:  Inductively coupled plasma  Neutralizer  RF ion thruster  Hollow cathode  Electron source

摘要:

为了研究适用于百瓦级电推力器的离子束流中和技术，基于电子鞘层模型、射频等离子体最优放电技术和通过插入探针实现快速点火的方法，设计了一套小型感性耦合射频等离子体中和器(RF plasma neutralizer，RPN)。实验研究了 RPN中和器的稳定工作条件和电子引出特性，实现了 RPN中和器稳定工作和电子有效引出。实验结果表明:电子引出特性主要取决于发射孔附近阳极斑的形成与否，而阳极斑的形成又主要受结构设计、工质流量和偏置电压等运行条件的影响；通过对 RPN运行条件的优化试验，获得了 55～150mA可调电子束流范围和较高的工质利用系数( 3.9～10.5)，满足离子束流中和需求；另外，实验中还观察到了电子束流随工质流量或偏置电压的迟滞现象。

Abstract:

In order to study the ion beam neutralization technology which is applicable to the electric thrust.er at the level of 100W，the mini inductively coupled radio-frequency plasma neutralizer(RPN)was developed.Electron sheath model and the optimal discharge techniques of RF plasma are used to design the neutralizer’s structures and stable operating parameters，and the fast ignition is achieved by inserting a floating probe. Then， the electron-extraction characteristics of RPN neutralizer were studied experimentally. Thus，the RPN neutraliz. er achieve a better working stability and electron-extraction performances. The experimental results show that theelectron-extraction performances mainly depend on the formation of anode-spot near the emission hole. However， the formation of anode-spot is mainly affected by the structural design，mass flow rates and bias voltage and oth.er operating conditions. Through the optimization experiments of RPN neutralizer，the electron-extraction range of 55-150mA and working gas utilization factor of 3.9～10.5 are obtained. This satisfies the requirements of de. sign. In addition，the hysteresis of electron-extraction current is observed with the regulation of mass flow rate or bias voltage.