霍尔推力器内部等离子体流场数值分析

Numerical analysis on inner plasma flow of hall effect thruster

关键词:  霍尔推力器+  内部过程  等离子体  流动分布  数值分析

Key words:  Hall effect thruster~+  Inner process  Plasma  Flow distribution  Numerical analysis

摘要:

建立以宏观电中性、不同种类粒子间滑移流动为基本假设的一维多流体简化模型,构造了相应的数值计算方法,用于分析霍尔推力器(亦称稳态等离子体推力器,简称SPT)的加速器通道内部物理过程。在适当边界条件以及适当模型常数条件下,能够获得无论在定性还是定量上都与实际比较接近的收敛的稳态解。结果显示,电势降落集中在出口附近,离子加速过程与该电势降落一致;在通道前半段电离比较剧烈,而在出口附近趋于平缓,出口电离度接近80%;由于焦耳加热作用,电子从出口截面向阳极漂移过程中,其温度由初始的约10eV首先提升到接近60eV的峰值,该峰值出现在离出口约1/3通道长度位置上;随后,由于越来越多的能量损耗于电离过程,到阳极附近电子温度降至约25eV。受其中的一些假设所限,本模型不能反映一些特殊区域和某些比较重要的物理过程,同时能够收敛的条件也受到了限制。

Abstract:

A simplified one-dimensional multi-fluid model was set up and corresponding calculation method was carried out analyze the accelerating channel of hall effect thruster (a.c. Stationary Plasma Thruster, ab. SPT). The model is based on the hypothesis of quasi-neutral and slipping-fluid between different kinds of particles. It was indicated from a concrete sample that, a steady convergent solution, which is close to reality qualitatively as well as quantitatively, could be obtained successfully under proper boundary conditions and adequacy model constants. Some phenomena are revealed from the results: (a). Drop of electric potential is concentrated around the exit, which coincide with the acceleration of ions; (b) Ionization rates are more intensive in the upstream half of the channel, relaxing down-steam near exit, with final ionization level approach to 80%; (c). During the course of electron-drifting from exit plane to anode plane, electron temperature first rises from about 10eV at the exit plane up to about 60eV at the plane of one-third channel length from exit, thanks to Joel heating, and then drops to about 25eV at anode surface because more and more electron energies are consumed by ionization processes. Hampered by its hypothesis, the model cannot reflect some special zone and other important processes; the conditions of convergence are also confined.