Dielectric breakdown properties of SF6–N2 mixtures in the temperature range 300–3000 K

Abstract

Reduced critical electric field strength (E/N)cr is an important indicator for the evaluation of dielectric breakdown of SF6 and its mixtures. This paper aims to analytically investigate the dielectric breakdown properties of SF6–N2 mixtures. First, (α − η)/N and (E/N)cr of SF6–N2 mixtures at room temperature, and then (E/N)cr of hot SF6 at several pressures are calculated and compared with other studies. The results confirmed the validity of the present calculation method and parameters. In addition, the electron energy distribution function, reduced ionization coefficient α/N and attachment coefficient η/N of SF6–N2 mixtures are obtained at different proportions and under 1 atm in the gas temperature range 300–3000 K. Then (E/N)cr can be determined when the effective ionization coefficient (α − η)/N = 0. The results show that in a certain temperature range, due to the effect of N2 on reduction in the proportion of high-energy electrons, (E/N)cr of SF6–N2 mixtures will be enhanced by increasing N2.