Statistical Model of the Creep Discharges in Air at the Dielectric Surface

The relation between the successive surface discharges across a dielectric surface under applied ac voltage was measured and analyzed. The discharges were measured by way of flash of light registration. The electronic set-up included two memories each having 32 x 32 channels working in two-dimensional regimes. The analysis of experimental data forces us to use Poisson´s statistics and consequently imposes a simple formula describing the probability of the creep discharges. The statistical model of the discharge cascades (for small overvoltages) and the average statistical model of the discharges (for larger overvoltages) are described by the formula. It has been postulated that a certain number of electrons is attached to the dielectric sample surface during the discharge. In effect, electrons liberated from the surface initiate the discharge.