微推力ECR离子推力器等离子体源电子获能计算分析

Calculation Analysis on Electron Heating within Plasma Source Used by Micro ECR Ion Thruster

关键词:  电子回旋共振  微推进  电磁场

Key words:  Electron cyclotron resonance  Micro-propulsion  Electromagnetic field

摘要:

为满足小型航天器的微推进需求，开展了微推力电子回旋共振(ECR)离子推力器的计算研究。实现该推力器的关键是ECR等离子体源合理的磁场和电场分布数值计算，从而使电子在穿过ECR谐振区时能够获得最大能量。为此以双环形永磁材料结构作为磁路，分别以直线形、环形和盘形微波耦合天线产生微波电磁场，同时改变等离子体源特征长度，利用有限元软件计算并分析ECR等离子体源内磁场和微波电场的分布规律以及电子在ECR区的获能规律。结果以微波输入功率5W、频率4.2GHz为例，发现环形耦合天线与较短等离子体源特征长度的结构组合可使电子在ECR区的获能指标达到最大且分布最佳。

Abstract:

To satisfy the propulsion need of small spacecrafts，it is essential to calculate characteristics of micro electron cyclotron resonance (ECR) ion thruster. To get the maximum energy absorbed by electrons when passing through ECR layer，calculation of reasonable magnetic and electric field distribution in the plasma source is a key problem. In this article，the conformation of magnetic circuit was formed by two annular permanent magnets，microwave electromagnetic fields were generated separately by the linear，ring and dish-shaped antennas，and characteristic lengths of plasma source were altered several times. Through the calculation by applying finite element method，the important distribution of magnetic and microwave electric fields，and energy to heat electron were obtained. It is found that with 5W power and 4.2GHz frequency of input microwave，the structural combination of ring coupling antenna and shorter characteristic length of plasma source allows electron heating index to get the maximum value and the optimal distribution in ECR layer.