Research on dielectric characteristics of SF6/N2 gas mixtures based on FEM-FCT

Based on dynamic characteristic of microscopic particles in discharge process, streamer discharge model is set up. Combining finite element method and flux corrected transport method, the paper simulate the streamer discharge process at SF
₆
/N
₂
with mixing ratio of 50%:50%. On this basis, experimental platform for gas discharge is set up, and breakdown voltages of SF
₆
/N
₂
gas mixtures are measured. Influences of mixing ratio and pressure on SF
₆
/N
₂
breakdown voltages is analyzed. The results show that electron number density in discharge gap is increasing with streamer moving forward, meanwhile electrons diffuse from high particle number density to low particle number density, and the peak value of electron number density reaches 3.0 × 10
¹⁵
/m
³
at 5.5ns. Dielectric strength of SF
₆
/N
₂
is higher than the value weighted according to partial pressure ratio, presenting synergistic effect. The synergistic effect is obvious when a small amount of SF
₆
is contained in gas mixtures.