Abstract: 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.

Key words: SF₆/N₂ gas mixtures, streamer discharge, electron number density, electric field distortion, dielectric strength, synergistic effect