摘要
为了描述微空心阴极内等离子体放电特性,采用二维流体模型对氩气微空心阴极放电进行了数值模拟。在工作气压4 42×10~4×10 Pa,放电电流1.0~2.5 m A范围内,微空心阴极内氩气放电处于正常辉光放电区域,计算获得的微空心阴极伏安特性及各种组分数密度与文献报道结果符合良好。数值模拟结果表明,在典型计算工况条件下,微空心阴极环形鞘层内电子温度可达20 e V;气体温度可高出室温几百K,说明微空心阴极内等离子体放电具有明显的气体加热效应。通过对体系内的化学动力学过程分析发现,在不同的区域内,Ar＋的产生机理不同。在阴极孔鞘层区内,高能电子直接电离基态原子占主导;在阴极孔中心处,电子冲击激发态电离占主导;在阴极孔外的放电区域中心轴线上,Ar＋的产生来自电子冲击激发态电离、Penning电离和电子直接冲击基态原子电离共同贡献。
Argon plasma was numerically simulated to describe the discharge characteristics of mierohollow cathode discharge （MHCD） using a two-dimensional fluid computational model. Results indicate that the MHCD operates in a normal glow discharge mode in the pressure（ 2×104 - 4 × 104 Pa ）, current（ 1.0-2.5 mA ） operating regime. Most predic- tions presented in this paper, such as 1-U characteristics and all species number densities, are in qualitative and quantitative agreement with the referred experimental results. Under the typical conditions, the electron temperatures in the ring-shaped cathode sheath region reach 20 eV. The discharge is characterized by significant gas heating since the peak gas temperatures are several hundreds of Kelvin above the room temperature for all cases. It is found that the pro- duction of ions is dominated by different processes in different regions by chemical-kinetic process analysis. In the cathode sheath region, electron-impact ground-state atom ionization is the predominant production mechanism, while electron-impact excited-state atom ionization in the center of the discharge dominates inside the hollow. At the center line of the discharge outside the hollow, the production rate of ions is mainly determined by kinetic processes involving elec- tron-impact excited-state atom ionization, Penning ionization and electron-impact ground-state atom ionization.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2015年第9期2965-2972,共8页
High Voltage Engineering
基金
国家自然科学基金(11072020
11275021)~~
关键词
氩等离子体
微空心阴极
辉光放电
电势
非平衡
数值模拟
argon plasma
microhollow cathode
glow discharge
electric potential
nonequilibrium
numerical simulation
