Electric field arising from a heterocharge accumulation on the surface of a solid insulator in a vacuum

The electric field arising from a heterocharge surface distribution present on a solid insulator is calculated as a function of insulator length at the solid insulator-vacuum interface, inside the solid insulator and in the vacuum. An enhancement in the field is observed at the cathode and anode junctions. The field enhancements at both electrode junctions age found to increase with increasing insulator length leading to the nonlinear dependence of the withstand voltage on insulator length.