Basic Erosion Processes of Oxidized and Clean Metal Cathodes by Electric Arcs

This paper reviews the considerable advances which have been made in recent years in understanding the basic processes involved in erosion of metal cathodes of electric arcs. These advances have been due to the use of scanning electron microscopy (SEM) which has revealed craters of 0.1-μm diameter, the use of arc durations down to a few nanoseconds, and recognition of the importance of oxide film on the cathode surface and control of this in experiments. The paper covers atmospheric pressure and vacuum arcs and clears up most of the confusion about such parameters as cathode emitting site current densities and lifetimes, at least for copper cathodes and to an extent for some others.