等离子体鞘层中朗缪尔探针吸收离子电流理论的数值模拟

Numerical Simulation of Ion Current Absorption by Cylindrical Langmuir Probe in Plasma Sheath

为了研究朗缪尔静电圆柱型探针半径对等离子体密度测量的影响以及鞘层空间电势分布等特性,在非热平衡条件下采用等离子体鞘层中探针吸收离子模型,对朗缪尔静电探针周围等离子体鞘层空间中的修正玻姆电流、OML理论鞘层空间电势分布、ABR理论鞘层空间电势分布、BRL理论鞘层空间电势分布以及三种理论对应的探针吸收离子电流进行了系统的数值模拟研究。计算结果显示,电子温度和等离子体密度对ABR理论鞘层空间电势分布存在显著影响,离子温度小于0.1倍电子温度时离子的温度效应对BRL理论鞘层空间电势分布的影响可以忽略;探针半径为1-3倍德拜长度时,OML理论、ABR理论及BRL理论预测的归一化离子电流近似相等,即三种理论给出近似相等的等离子体密度。

Here,we systematicallyaddressed the impact ofthecylindrical Langmuir probe＇s radius on plasma diagnosis and potential distribution in plasma sheath. The key variables,including the amendment Bohn current around the probe,potential distributions in plasma sheath and probe＇s absorption ion currents predicted by OML,ABR and BRL theories,respectively,were numerically simulated with the non-thermal equilibrium ion absorption model of cylindrical Langmuir probe. The simulated results show that the validity of OML,ABR and BRL theories significantly depends on the probe＇s radius and plasma behavior. For example,when the probe＇s radius lies in 1 ~3 Debye-length,OML,ABR and BRL theories predict almost the same normalized ion currents（ or plasma density）;the electron temperature and plasma density strongly affect the sheath space potential distribution calculated by ABR theory; and,an ion temperature,lower than 10% electron temperature,little influences the sheath potential distribution evaluated in ABR theory.