Abstract
A remarkable characteristic of a vacuum arc cathode spot, which can remove an oxide layer, is that it moves across the metal surface. However, the contribution to the moving mode of the vacuum arc cathode spot remains unclear. This study elucidated the contribution to moving mode of the vacuum arc cathode spot as affected by the oxide layer thickness. Experiments were conducted using an SS400 cathode and a cylindrical copper anode. A high-speed video camera recorded the cathode spot movement with ND (Neutral Density) and a band pass filter. The obtained images were then analyzed using plasma image processing. The cathode spots have four moving modes: oxide layer removal, split, stagnation at the boundary between the oxide layer and the processed surface, and high-speed movement on the processed surface. Oxide layer thickness affects the cathode spot moving mode because of the maintenance of the current continuity of the cathode spot with oxide layer vaporization and ionization. Oxide layer thickness affects the cathode spot movement.
