Inhomogeneous field breakdown in GIS-the prediction of breakdown probabilities and voltages. II. Ion density and statistical time lag

For pt.I see ibid., vol.3, no.3, p.923-30 (1988). An improved model for the calculation of statistical time lags in SF/sub 6/ insulated electrode arrangements for positive impulse voltage is presented. On the basis of physical considerations, the production rate of initial electrons is ascribed to the local density of negative SF/sub 6/ ions and to field dependent electron detachment. Values of negative ion densities are measured directly, while the detachment coefficient is determined by a fitting procedure to measurements of statistical time lags.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>