Influence of space charge on breakdown strength of PET foil

Results of studies on the influence of the space charge implanted by corona charging or electron-beam irradiation on the electric strength of PET (polyethylene terephthalate) foil are presented. Values of impulse breakdown voltage as a function of corona charging voltage are presented for 36- mu m and 180- mu m PET foil samples. It is shown that for both thicknesses the breakdown voltage tends to increase in the case of positive corona voltage and to decrease in the case of negative corona voltage. This tendency was observed only when the measurements were performed at the positive voltage on the electrode.