SURFACE DISCHARGE SIMULATION IN SF6 AND N2 MIXTURES WITH A PLASMACHEMICAL MODEL

SF6–N2 mixtures are becoming the best alternative for SF6 in electrical systems. Plasmachemical modeling and the results of a positive surface streamer are reported in this paper. The model exhibits excellent streamer transition from the gas gap to the insulator surface. The surface charge accumulations on the dielectric insulators are compared and discussed. Results showed that the density of negative ions is much larger than that of electrons in the surface streamer channel. The dominant ${\rm SF}_{6}^-{$} and less pronounced ${\rm SF}_{5}^-{$} constitute the main negative ions in the electronegative surface streamer because of the strong electron attachments to SF6 molecules.