Dependence of the electric field on accumulation of a homocharge on the surface of a solid insulator

Under certain conditions, the insulator surface may be charged negatively near the cathode and positively near the anode. Taking into account the surface charges, the electric field is calculated as a function of insulator length-and for two solid insulator materials at the interface, at the interior of the solid insulator and in the gap (gaseous or vacuum). An enhancement in the field is observed at the surface of the insulator at locations away from the electrodes and a reduction is observed near both electrode junctions. The effect on the withstand voltage of the insulating gap is briefly discussed.