场致发射电推力器羽流分布特性仿真

Simulation of Plume Distribution Characteristics of FEEP Thrusters

关键词:  场致发射电推力器  PIC  结构参数  羽流  发散半角

Key words:  Field emission electric propulsion  Particle-In-Cell  Structural parameters  Plume  Divergence half-angle

摘要:

场致发射电推力器（FEEP）是微型电推进装置的典型代表。为深入理解结构参数对推力器性能的影响机制，本文采用PIC粒子模拟方法进行泰勒锥射流纳米尺度结构至宏观毫米尺度结构的羽流场仿真，并分析结构参数变化导致的羽流形貌差异及其对推力器性能参数的影响。研究结果表明：发射极高度是决定推力器束流是否会分叉的关键参数，低于300μm的发射极高度易于导致束流分叉并严重影响推力器性能和寿命；引出栅极槽宽是决定束流发散角和推力比冲性能的关键参数，其影响幅值可达30%~50%，羽流发散角随槽宽增加而增大，推力比冲随之减小；发射极-引出栅极间距对推力器性能影响相对较小，可在较大范围内支持推力器稳定高效工作。根据FEEP推力器性能随结构参数的变化规律，建议结构参数取值范围为：发射极高度500~1000μm，引出栅极槽宽2000μm左右，发射极-引出栅极间距360~1300μm。

Abstract:

The Field-Emission-Electric-Propulsion（FEEP） thrusters is a typical of miniature electric propulsion devices. In order to deeply understand the influence mechanism of structural parameters on thruster performance，the Particle-In-Cell particle simulation method was used to perform the plume simulation of the nanoscale structure of the Taylor cone jet structure to the macroscopic millimeter scale structure. The difference of plume shape caused by the change of structural parameters and its influence on the thruster performance were analyzed. The results show that the emitter height is the key parameter to determine whether the thruster beam will bifurcate. When the emitter height is lower than 300μm， it is easy to lead to beam bifurcation and seriously affect the performance and life of the thruster. The accelerating grid slot width is the key parameter to determine plume divergence angle， thrust and specific impulse， and its influence amplitude can reach 30%~50%. Plume divergence angle increases with the increase of the accelerating grid slot width， while thrust and specific impulse decreases. The distance between emitter and accelerating grid has relatively little influence on the performance of FEEP thruster， which can support the stable and efficient operation of FEEP thruster in a large range. According to the variation law of FEEP thruster performance with structural parameters， the recommended value range of structural parameters is emitter height 500~1000μm， accelerating grid slot width 2000μm， emitter - accelerating grid spacing 360~1300μm.