磁场位形对双级霍尔效应推力器离子输运的影响

Influence of Magnetic Field Configuration on Ion Transportation of Double Stages Hall Effect Thrusters

离子输运是影响电势阱式双级霍尔效应推力器(DSHET)性能的一个重要物理过程,合理的磁场位形对离子输运有重要影响,为分析其影响机理,通过Langmuir探针诊断实验,分析了不同磁场位形环境下电离级电势阱和中间电极处电势垒等特征参数的变化,同时结合双面探针收集离子定向电流,得到了不同磁场位形下的空间电势分布和中间电极处电势垒大小对离子输运电流的影响关系。实验发现,磁场位形改变对空间电势分布的影响明显。以中间阳极附近的零磁点作为磁场特征参数,在不同磁场工况下,零磁点越接近通道的中心线,则电离级电势阱的分布越均匀,同时中间电极处电势垒也达到最小值(9V),这样的空间电势分布能有效抑制离子在金属壁面上的损失,减小离子输运的阻碍电势垒,可提高离子输运电流10%。研究结果表明双级霍尔效应推力器的离子输运过程主要受电离级电势阱分布均匀性和电势垒大小的影响,磁场位形在一定程度上决定了电势分布,零磁点径向位置应位于放电通道的径向中心位置,这样离子输运最畅通,电离级作用最大化。

The ion transportation between ionization stage and acceleration stage is an important physics process that affects the characteristic of ionization stage of double stages Hall effect Thrusters（DSHET）,and is remarkably affected by reasonable configuration of magnetic field.To analyze the mechanism,the potential well and potential barrier around intermediate electrode were monitored under different magnetic field configuration with Langmuir probes,and the ion transport current was measured with a double sides Langmuir probe.Moreover,the effect of space potential distribution and potential barrier on the ion transport current under different magnetic field configurations was obtained.Experimental results revealed that the magnetic field configuration obviously affected the spatial electric potential distribution effect.As a characteristic parameter,when the zero magnetic point was closer to the channel center line,the distribution of ionization potential trap became more homogeneous,and electric potential barrier also reached the minimum（9 V）.The distribution of ionization potential could reduce the ion loss on metal surface and the potential barrier which hindered the ion transport,and the ion transport current could be improved by 10%.It is concluded that the ion transportation of DSHETs is mainly affected by ionization potential trap distribution uniformity and the size of the potential barrier,the magnetic field configuration determines the electric potential distribution primarily,and the radial position of zero magnetic point should be located at the center of discharge channel so that the ion transport is the most smooth,and the role of ionization stage is maximized.