The Influence of Anode Material on the Anode Spot Formation in High Current Vacuum Arcs

In high current vacuum arcs, the contact materials fundamentally decide the arc behavior. The objective of this work is to experimentally study the influence of anode contact materials on the anode spot formation. A pair of Helmholtz coils is set to generate axial magnetic fields. A high speed video camera is used to record the arc evolution. The anode spot formation and the threshold currents for different anode materials are studied. To eliminate other factors that may affect the anode spot formation. The discharge geometry and the external axial magnetic field remain the same. In the experiments, four anode contact materials of Fe, Cr, Mo and W are used. Moreover, the cathode material remains Cu. Therefore, four cathode-anode materials sets are Cu-Fe, Cu-Cr, Cu-Mo and Cu-W. The anode spot threshold currents for these four materials sets are 9.5 kA
rms
, 11.2 kA
rms
, 14.1 kA
rms
and 16.3 kA
rms
, respectively. Compared to the previous work, the impact of cathode materials is eliminated. The experimental results could directly reflect the influence of the anode materials on the anode spot formation.