Impulse flashover along the outer surface of a cylindrical dielectric solid with a gas layer inside

Impulse flashover voltage along the outer surface of a layered dielectric composition, composed of two coaxial hard glass cylinders and an inner gas layer, is known to have a V-shaped curve as a function of pressures inside the gas layer. It is the purpose of the paper to clarify the reason for this V-shaped curve. Variation of electric field intensity along the outer surface caused mainly by ionisation in the gas layer, and partly by the residual charges on the inner surface of the outer cylinder is found to play an important role in determining the flashover voltage