Lichtenberg Figures on Various Electrical Insulating Materials

The surface discharge on insulating solid materials was recorded by a camera with high speed films. This simple method was found to be useful for the investigation of the surface discharge on various insulating materials. Lichtenberg figures on the surface of seven types of insulating material were determined by this method. The starting voltage for the formation of Lichtenberg figures was found to depend on the surface resistance of the insulating material, while the rate of the development of surface discharge with the applied voltage, depends on the relative permittivity of the insulating materials. It is expected that the dielectric strength of an insulating material can be improved by covering its surface with highly resistive materials.