SF6/N2流注放电仿真及协同效应研究

建立反映气体放电过程中粒子运动特性的二维流体模型，采用有限元和通量校正传输法对该模型进行数值求解，计算了50%SF₆+50%N₂在均匀电场下的放电规律，模拟了流注发展过程中粒子密度的分布情况，分析放电过程中带电粒子对均匀电场的影响。搭建气体放电实验平台，测量平板电极下绝缘间隙5 mm时SF₆/N₂混合气体的击穿电压，将SF₆/N₂击穿电压的实测值与折算值进行对比，研究不同混合比、气体压强对SF₆/N₂协同效应的影响。结果表明：随着流注向阳极运动，放电间隙内的电子数密度不断增大；在放电初始阶段，空间电荷对电场的影响很小，随着电荷数量不断增加，空间电场产生明显畸变现象。SF₆/N₂混合气体击穿电压的实验测量值大于折算值，且SF₆含量越高，实测值和折算值越接近。可以看出，SF₆/N₂的协同效应在含有少量SF₆时较明显，而当SF₆含量较高时，混合气体的协同效应减弱。

Research on Streamer Discharge Simulation and Synergistic Effects of SF6/N2

A two-dimensional fluid model is set up in this paper to depict the kinetic characteristics of particles in gas discharge process. The finite element method and flux corrected transport method are used to solve the model and to get the features of discharge rules for 50%SF₆+50%N₂ in uniform electric field, simulate distributions of electron number density in streamer process, and the effects of charged particle on uniform electric field are analyzed. A gas discharge experimental platform is established to measure the breakdown voltages of SF₆/N₂ mixtures with the lower insulation gap of plate electrode at 5 mm, and the influences of mixing ratio and gas pressure on SF₆/N₂ synergistic effect are studied by comparing experimental values with calculated values. The results show that the electron number density increases with streamer moving to anode, and that the influence of space charges on electric field is small in initial phase while obvious electric field distortion will occur with the increase of electric charges. The experimental breakdown voltage of SF₆/N₂ gas mixtures is larger than the calculated one, and their difference becomes smaller with the increase of SF₆ content, which means that the synergistic effect of SF₆/N₂ is obvious when the SF₆ content is small while the effect will be weakened when the SF₆ content is high.