Moving Speed of Cathode Spot Affected by Transverse Magnetic Field

摘要

A remarkable characteristic of a cathode spot in a vacuum arc is that the cathode spot moves around the metal at high speed. Cathode spots of vacuum arc have been used for cleaning metal oxide surface. In addition, the adhesion strength increases in the case of thermal spraying because the roughness on the metal surface is formed. The removal process of the oxide layers is not clear when a magnetic field was applied. In this paper, the removal process of oxide layers was observed in order to control the cathode spot movement with transverse external magnetic field. Experiment were performed using a SS400 cathode work piece. A high-speed video camera recorded the cathode spot. Then, the obtained images were analyzed by using plasma image processing. As a results, the cathode spot moves with retrograde motion under removing the oxide layer when a magnetic field was applied. However, the cathode spot is not always the retrograde motion. Then, the moving speed of cathode spot increases with increasing the magnetic field. Also, the removal area speed of oxide layers dose not change significantly when the magnetic flux density changes.