Removal Process of Cathode Spot of Vacuum Arc with Vapor from Oxide Layer

摘要

A remarkable characteristic of a cathode spot of a vacuum arc is that the cathode spot moves around on the metal surface. A cathode spot can remove an oxide layer. Cathode spots of vacuum arcs have been used for cleaning metal oxide surfaces. However, the influence of an oxide layer on cathode spot movement remains unclear. As described herein, cathode spot movements on an oxide layer surface and a metal surface were measured to determine the cathode spot movement. Experiments were performed using a SS400 cathode and a cylindrical copper anode. A high-speed video camera recorded the cathode spot movement with ND and band path filter. Then, the obtained images were analyzed using plasma image processing. The cathode spot movement was generated mainly on the boundary layer, but sometimes on the processed surface. The cathode spots always moved boundaries between the oxide layer and processed layer; however, it sometimes split, stagnation and High speed movement on the bulk. When the cathode spot exists at the boundary, the vapor is generated at the boundary layer. In the case of oxide layer removal, the brightness of cathode spot and O I spectrum are high. Therefore, the oxide layer serves an important role for cathode spot existence because of oxide layer vaporization.