Effect of the thickness of insulators on the build up of a space charge distribution

When an electric stress is applied to an insulator, a space charge distribution may develop and have a strong effect on the electric strength of the material. It has already been reported that the thickness of the insulator may have an effect on the observed phenomena. In this paper we have investigated this effect, using the pressure wave propagation (PWP) method, and present experimental results which have been obtained on pure polyethylene samples of different thicknesses with similar electrodes, submitted to the same applied electric field. These results show that the distribution of space charge depends on the thickness for a given material, but not the maximum value of the charge density. The effect of dopant is also considered by comparison with already reported data.