Neasuring Electric Field by Using Perssure Sensitive Elements

The electric forces acting on an electrode surrounded by gas or liquid can be substituted by a system of surface forces alone. The resulting surface force density, foundby using the Maxwell stress tensor, is proportional to thesquare of the electric field in the dielectric. Thisrelation between pressure and electric field is used fordevelopment of a method for measuring electric fields nearelectrode surfaces.The method is based on the use of a thin circular metalmembrane which is mounted over a cavity in the electrodesurface so that the membrane forms a part of this surface.An electric field will set up forces which try to pull theelectrodes together. When the membrane is thin enough itwill bend out. This movement, only fractions of a micrometer,er, can be detected by using fier-optic transmissiontechniques.Measurements have shown the practicality of the method.As an example of the application of the method, measurementshave been performed on the "Skagerrak Cable".