Chapter V the breakdown of dielectrics

The influence of the nature of the cathode metal upon the breakdown of liquid dielectrics has been studied by many investigators. However, the sensitivity of the electron emission characteristics of a metal to the physical and chemical condition of its surface makes it very difficult to obtain reproducible results, Bragg, Sharbaugh, and Crowe (1) have attempted to bypass this difficulty by using an electrolyte solution as a cathode; the amount of emission is controlled by the concentration of the electrolyte in solution. Consideration of the space charge formation leads to a qualitative theory which predicts the manner in which the electric strength of a liquid will depend upon the concentration of the solution used as cathode. Experimental verification of this theory is provided by a study of the variation in the electric strength of benzene when measured with a series of aqueous LiCl solutions which have different concentrations (10⁻⁵ to 5N).