DIELECTRIC BEHAVIOR OF SF(6) IN NONUNIFORM FIELDS

The impulse breakdown of 20 mm rod-plane gaps in SF6 has been investig ated using impulse wavefronts in the range 10 ns to 10 mus. The SF6 pr essure is varied between 1 and 5 bar and results have been obtained wi th non-irradiated and gamma irradiated gaps for both polarities. The d ischarge regimes are studied for each withstand and breakdown case usi ng a complete set of diagnostic methods. Particular attention has been paid to negative polarity as experimental studies in this area are st ill scarce.