Electric stress in a circular cylindrical gaseous cavity in a solid dielectric, the axis of the cylinder being parallel to the field

A circular cylindrical gaseous cavity in a solid dielectric is considered, the axis of the cylinder being paralle to the electric field. The dielectric is contained between two infinite plane parallel electrodes, whose distance apart is not great compared with the dimensions of the cavity. The distribution of the potential in the cavity has been calculated, in both alternating- and direct-voltage conditions, by a finite-difference technique, and the mean electric stress along the axis of the cavity determined in terms of the stress in the solid. Experiments made with an electrolytic tank have verified the calculations.