Conduction and breakdown in vacuum

Abstract

One of the areas of most active interest in with conduction in vacuum over the past year has been the behavior of vacuum arcs at high currents. The subject is of enormous practical interest to vacuum interrupter development and involves a variety of physical processes the interactions of which provide fertile ground for novel experimental and theoretical investigations. The vital question concerns the Jeckyl and Hyde character of the vacuum arc anode junction. At low currents the anode is diffuse and passive with the anode terminal acting largely as a charge collector over its entire exposed area. At high currents the anode end of the arc may contract causing a high concentration of energy input to the electrode surface. This transition results in severe melting and violent ejection of anode metal. A variety of investigations on this subject are discussed in the section on The Arc Anode and include such subjects as the effects of axial magnetic fields, the visual appearance of the high current arc under different ignition conditions,, the current flow pattern between cathode and anode at high current, and the ion flux distribution from the cathode to the anode.