毛细管脉冲等离子体推力器等离子羽流分团现象与等效速度测量

Plasma Plume Splitting Phenomena in Capillary Discharge Based Pulsed Plasma Thruster and Equivalent Velocity Measurement

关键词:  毛细管脉冲等离子体推力器  等离子体羽流  飞行时间法  等效速度  二次建立过程

Key words:  Capillary discharge based pulsed plasma thruster  Plasma plume  Time-of-flight method  Equivalent velocity  Secondary establishment process

摘要:

毛细管型脉冲等离子体推力器采用固态工质，电热加速机制，结构简单可靠，是一种具有应用价值的微纳卫星低功率电推进系统。本文建立电学和光学联合诊断系统，对毛细管脉冲等离子体推力器等离子体羽流演变过程进行了研究。由于放电电流振荡，推力器等离子体羽流存在二次建立过程。初始阶段等离子体羽流中主要包含带电粒子组分，二次建立阶段等离子体羽流主要包含中性成分。利用光电二极管阵列和窄带滤光片建立了飞行时间法，获得了不同放电电压、腔体内径和腔体长度下等离子体羽流分团的等效速度演变特性。结果表明，电热加速机制能够使带电组分和中性成分获得较为良好的加速效果（>10km/s）。在一定放电能量下，放电腔体长度小于25mm有利于获得较优性能参数。等离子体羽流等效速度结果能够较为准确地反映推力器输出比冲和效率参数变化规律，可作为推力器输出参数便捷有效的评估手段。

Abstract:

The capillary discharge based pulsed plasma thruster adopts solid propellant， electrothermal acceleration mechanism， resulting in a simple and reliable structure. It is of great value in low-power electric propulsion system for micro-nano satellites application. In this paper， an electrical and optical joint diagnostic system was established to study the evolution process of the plasma plume of a capillary discharge based pulsed plasma thruster. Due to the oscillation of the discharge current， a secondary establishment process was observed in thruster plasma plume. In the initial stage， the plasma plume mainly contained charged particle components， and neutral components mainly showed up in the secondary establishment stage. The time-of-flight method was established based on photodiode arrays and narrow-band filters， and the equivalent velocity evolution characteristics of plasma plume sub-clusters under different discharge voltages， cavity inner diameters and cavity lengths were obtained. The results showed that the charged components and neutral components were both able to reach a high velocity （>10km/s） under electrothermal acceleration mechanism. With a certain discharge energy， it showed that the discharge cavity length less than 25mm was conductive to obtaining better performance parameters. The plasma plume equivalent velocity results could accurately reflect the variation law of thruster output specific impulse and efficiency parameters， and it could be used as an effective and convenient method for thruster output parameters evaluation.