Cathode Spot Movement of a Low-Pressure Arc for Removing Oxide Layer

A remarkable characteristic of the cathode spot of a low-pressure arc is that it can remove an oxide layer preferentially. Recently, the cathode spot of a low-pressure arc has been used for cleaning metal oxide surfaces before thermal spraying or surface modification. However, few reports have described the cathode spot movement or the oxide removal process. This experiment was carried out using the SS400 cathode workpiece and a cylindrical copper anode. The cathode spot movement was recorded using a high-speed video camera. The images were later analyzed using plasma image processing. The workpiece surface was covered with a thick oxide of 9.67 mum. The workpiece surface was analyzed using a laser microscope after processing. The cathode spot movement shows differences as the processing time increases and as the oxide layer roughness changes.