Correlation of Electrical Breakdown and Centers of Strong Electron Emission on a Zone-Refined Iron Cathode in Vacuum

Abstract

The present work is a study of the whiskerlike protuberances upon the surface of a ½‐in‐diam zone‐refined electrode in vacuum. The experimental technique employs a phosphor screen parallel to the electrode surface. The electron emission from the surface protuberances are projected upon this screen. The experiment consisted of more than 40 trials, each trial involving the recording of an emission pattern, the determination of a Fowler‐Nordheim plot, and the application of 60‐cycle high voltage sufficiently large to produce occasional breakdown. Further, the electrode surface was photographed directly during each application of 60‐cycle voltage so that the locations of individual breakdown events could be recorded. In general, good correlation was found between the location of emitters as determined from the phosphor screen display and the locations of breakdowns.