Measurements of pre-breakdown currents in dielectrics with a cathode-ray tube

A. Introduction IN order to obtain more information regarding the mechanism of electrical breakdown in insulating liquids, a number of experimenters^1,2,3 have studied current flow as a function of applied voltage, using high-sensitivity d-c amplifiers with indicating instruments having relatively long-time constants. Such instruments will not follow rapid changes in current where the time intervals are of the order of milliseconds or less. Therefore we decided to investigate the possibility of using a cathode-ray tube as a current detector to follow current changes just preceding breakdown. This paper describes current measurements in liquids with 200-microsecond impulse voltage waves and current measurements in liquids and solids with gradually increasing unidirectional voltage applied to the specimens.