Experimental investigation of cathode current density distribution in vacuum arc based on ring-shaped electrode

In this paper, based on ring-shaped cathode and cup-shaped axial magnetic field (AMF) anode configuration system, the current density distribution on the cathode surface was measured. Vacuum arc appearance also was observed by a high-speed camera. The experimental results showed that the current density on the cathode was of the order of 10(6)-10(7) A/m(2). For lower current (3 kA), the current density distribution was relatively uniform. For higher current (6 kA), due to the weaker AMF of cathode side, the arc was more seriously constricted and the current density distribution was more nonuniform, the current density of central area was much larger than that of other peripheral regions in the cathode surface. Compared with two cup-shaped AMF electrode systems, the current constriction was more significant for the same current and gap distance.