Spectrum and number for cathode spot with changing current

Summary form only given. The vacuum arc processing with a cathode spot is expected to comply with and support the social goals of three Rs. A remarkable characteristic of a cathode spot of a vacuum arc is that the cathode spot moves around 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 current change for the parameter of the cathode spot on the boundary layer remains unclear. As described in this paper, the number of the cathode spots, the brightness, and the areas on the surface of boundary layer when the current changed were measured. Experiments were performed using a SS400 cathode and a cylindrical copper anode. Argon was used as the ambient gas. The pressure was adjusted to 100 Pa. 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, however sometimes on the processed surface. The cathode spot moves on the processed surface very fast. When the cathode spot exists at the boundary, the vapor is generated at the boundary layer. The number of cathode spots increases with increasing the current. When the current decreased, one of the cathode spots disappeared on the surface. The brightness of the cathode spots depend on the current a little. When the current increases, the cathode spots were split. The intensity of oxygen spectrum is higher than that in the case of previous split. When the number of cathode spot is reduced, the oxygen spectrum was reduced. The dependency of the areas of cathode spots with the current was elucidated.