空间电动力绳系电流峰值点变化规律研究

Investigation on Change Laws of Current Peak Position in Electrodynamic Space Tether

为研究电流峰值点在几种影响因素下的变化规律,建立一种能够捕捉绳系电子发射与收集自洽平衡过程的新算法--电路空间耦合算法。为验证该方法的计算精度,以1.35kW霍尔推力器为等离子体源,在真空舱内开展绳系的电荷收集试验,在电路参数方面,计算精度约为12.8%,在场参数方面,计算精度约为3.6%。在此基础上,针对不同偏置电压、绳系长度以及绳系直径,对绳系的绳上电流分布、电势分布以及空间电势分布等参数进行数值计算。结果显示:电动力绳系的电流峰值点会随着偏置电压升高、绳系长度增加及绳系直径增大而发生比例上的向阳极端漂移,揭示了电子轨道运动限制的机制在各类壁面电荷输运机制中占优,导致电流峰值点漂移的产生。

In order to precisely study the self-consistent process between the collection and emission of electrons in a whole electrodynamic tether system,a new hybrid model named 3D circuit and space coupling calculation(3D-CSC)has been established.This model can help to study the change law of peak position under several influencing factors.In order to verify the feasibility and accuracy of 3D-CSC model,experimental tests of current collection using a bare tether have been conducted,and a 1.35 kW class Hall thruster is employed as the plasma generator in the vacuum chamber.Comparisons between calculation and measurement results show that the error of calculation in circuit is about 12.8%,while in space is about 3.6%.Based on 3D-CSC,we simulated the steady-state operating characteristics of an on-orbit electrodynamic tether including the current and potential distribution on tether,as well as the plasma potential distribution in space,under the working conditions of different bias voltages,different tether lengths or diameters.The calculation results showed that,the current peak position would move to the anode end with the bias voltage increasing,the tether length increasing or the tether diameter increasing.The present study revealed that the difference of the three types of charge transportation,which are the orbital motion limit,the thermionic emission and the secondary electron emission,respectively,was the reason of the current-peak-position change.