Intrinsic Electric Strength of Polythene

Abstract

THE work of Austen and Pelzer¹ on the use of recessed specimens for measurement of the electric strength of dielectrics suggested that with specimens of this type experimental verification of the theories of breakdown developed by Frohlich and von Hippel^2,3 might be possible. Frohlich's recent extension⁴ of his theory predicts : (a) that the electric strength should be independent of thickness until the latter approaches the order of the electronic mean free path, when the electric strength should increase with decreasing thickness; and (b) that below a certain critical temperature the electric strength should either increase with temperature or be nearly independent of temperature, while above this critical point the electric strength should decrease with increasing temperature according to the relation , where F is electric strength and T is absolute temperature.