低气压He/N_2混合气体的辉光放电数值模拟

Numerical Simulation of He/N_2 Mixture Glow Discharge at Low Pressure

针对低气压下含有少量氮气杂质(体积分数为10^(–6)~10^(–4))的氦气辉光放电特性进行研究,通过建立相应的二维流体模型,利用COMSOL有限元法数值求解了基本物理方程,得到了放电气隙击穿电压以及内部物理参量的空间分布,分析讨论了氮气杂质的含量对低气压下氦气辉光放电的影响。研究结果表明:随着杂质含量的升高,由于氮分子和氦亚稳态原子的彭宁电离过程降低了击穿电压,因此气隙维持电压降低,回路电流升高。并且由于彭宁电离为放电提供了较多电子,导致电子数密度升高、电场强度降低、电子温度降低。

We focused on the characteristics of helium glow discharge with small nitrogen impurities （with volume frac- tion of 10^-6-10^-4） at low pressures. We proposed a two-dimensional fluid model and calculated the elementary physical equations by a finite element method in COMSOL.Moreover, we analyzed the influence of small nitrogen impurities on the helium glow discharge at low pressures. The results show that Penning ionization process of nitrogen molecule and metastable helium lowers the breakdown voltage, and increase in the amount of nitrogen in the mixture will result in the decrease of maintaining voltage and the increase of current. In addition, the electron density will increase, and the electric field and electron temperature in plasma will decrease. This is mainly caused by the Penning ionization process which can provide sufficient electron for the discharge space.