放电室长径比对射频离子推力器影响的数值模拟研究

Numerical Study of Effects of Discharge Chamber Length to Diameter Ratio on Radio Frequency Ion Thruster

关键词:  射频离子推力器  全域模型  长径比  工质流率  数值研究

Key words:  Radio frequency ion thruster  Global model  Length to diameter ratio  Mass flow rate  Numerical study

摘要:

为获得推力器的性能与推力器工况之间的变化规律，利用等离子体密度平衡方程、中性气体密度平衡方程、中性气体功率平衡方程、电子功率平衡方程构成的全域模型对氙工质射频离子推力器开展了数值模拟研究。结果表明，放电室长径比（L/R）的改变引起放电室壁上消耗功率的变化，从而影响推力器的性能。在放电室体积和工质流率不变的情况下，放电室的开口面积越大，越有利于射频功率的转换和推力器性能的提升。此外，改变工质流率导致离子间碰撞平均自由程和碰撞频率发生变化，进而使推力器的射频功率转换效率、推力效率、推功比随工质流率的增加而增加，工质利用率随着工质流率的增加而减小。

Abstract:

In order to achieve the variation laws of performance along the operating condition of the radio frequency ion thrusters， the global model is employed to numerically study the xenon radio frequency ion thruster. The model composes by the plasma density balance equation， neutral gas density balance equation， neutral gas power balance equation， electron power balance equation. The results show that the length to diameter ratio of the discharge chamber has an effect on thruster performance， because the power consumed on the chamber wall is changing with the draw ratio. The power transfer efficiency and the performance of the thruster are increasing with the increase of the opening area of the discharge chamber， when the volume of discharge chamber and flow rate of propellant are constant. On the other hand， the radio power transfer efficiency， thrust efficiency， thrust power efficiency increase and mass utilization efficiency decreases with mass flow rate increasing， because the collision frequency and collision mean-free path are varying with the rate of the propellant.