Cathode Phenomena with Arcs and Breakdowns in Vacuum

A short review is given on cathode phenomena in vacuum. Based on experimental results about temporal and spatial development of craters, arc spots and breakdown flares, conclusions are drawn with respect to the dynamics of crater heating, the connection of craters with spots, the current density, the reason of arc spot movement, the nature of different spot types, and the analogy of cathode flares with arc cathode spots. Referring only to surface processes, some general results could be obtained which allow a unified description of various cathode phenomena.