PREDICTION OF BREAKDOWN IN SF6 UNDER IMPULSE CONDITIONS

Prediction of fast transient voltage-induced breakdown in quasi-homoge neous field geometries requires compounding the breakdown probability over time, while taking into account the field-dependent probability o f electron detachment. In this paper, a breakdown probability model ha s been developed to predict the impulse breakdown under quasi-uniform fields, as this is the fundamental condition, the knowledge of which f acilitates computation of breakdown probability under more complex con ditions. The model will facilitate computation of breakdown probabilit y under more complex conditions. It accounts for the effect of the str eamer formation length on the critical volume and the probability of i nitial electron production by electron detachment from negative ions. The proposed model has been verified through comparison with the measu red impulse breakdown probabilities. The predicted breakdown probabili ties are in good agreement (+/-10%) with those measured.