离子能量分析器测量特性的仿真研究

Simulation study on measurement characteristics of ion energy analyzer

针对空间等离子体及其模拟环境、空间原子氧及其模拟环境对离子能谱测量的需要,利用仿真软件COMSOL,对离子能量分析器的低能离子测量特性进行了仿真研究。介绍了离子能量分析器的工作原理,对离子能谱测量过程进行了公式推导。通过对三种待选仪器设计方案进行离子透过率仿真分析,确定了一种较优的仪器设计方案。多种离子温度下的误差分析结果也表明,该设计方案能够较为准确地测量离子能量分布。分析了电场畸变、等离子鞘层、栅网对齐方式和离子温度对测量结果的影响,根据仿真结果对一些仿真实验现象做出了合理的解释。

The ion energy analyzer(IEA), also known as the retarding potential analyzer(RPA), is widely used as an important tool for measuring plasma energy in situ and is widely used in ionospheric detection satellites. The ion energy of the ionosphere is too low to be stabilized, thus the measurement characteristics of the IEA can ’t be effectively studied through experiments. As there is no such problem in simulation, simulation has become a powerful tool for studying IEA. This paper analyzes the low-energy ion measurement characteristics of the IEA through the simulation software COMSOL, introduces the working principle of the IEA, and gives a comprehensive formula derivation for the ion measurement process. Based on simulation and analysis of three candidate design schemes, one of the schemes whose transmission curve is closest to the ideal step function is chosen. In theory, the measurement results of this scheme have the least error. The comprehensive error analysis results at various ion temperatures also show that the gap between the measurement results and the theoretical value of the scheme is narrow. The ion energy distribution can be measured more accurately. Finally, the effects of electric field distortion, plasma sheath, grid alignment and ion temperature are studied. According to these simulations, some experimental phenomena can be reasonably explained.