Dielectric breakdown of a residual SF/sub 6/ plasma at 3000 K under diatomic equilibrium

A residual plasma at 3000 K and under diatomic equilibrium is left inside an axially blown gas blast SF/sub 6/ circuit breaker after the thermal extinction of an arc. The breakdown of such a residual plasma depends on the electron generation and loss mechanisms. Altogether six ionization and chemical reactions relevant to the time scale of breakdown have been taken into account. It has been found that the critical field strength for breakdown is proportional to the pressure and is equal to 2.0 V/(m.Pa). This field strength is in agreement with the experimental results.