Experimental study of anode current density distribution in high-current vacuum arcs

In this paper, anode current density distribution in high-current vacuum arcs have been investigated experimentally based on the split anode and cup-shaped axial magnetic field (AMF) cathode configuration system. The anode surface was divided into four areas by split: one central area with a diameter of 18mm, and three symmetrical peripheral fan-shaped areas with the internal and external diameters of 22 mm and 60 mm, respectively. The contacts material was CuCr25 and the arc current varied from 6kA to 14kA (rms). The currents of the four areas on the anode contact were measured by four Rogowski Coils outside of the vacuum chamber, and the anode current density of each areas was determined by the area and current of regions. From the experimental results, the peak anode current density of central area on the anode surface increased from 14.4 A/mm² to 37.7 A/mm², accompanied with the arc mode from the intense arc mode (14kA) from the diffuse arc mode (7.6kA). Moreover, the current density distribution became more non-uniform as the current increased, and the current density of the central area was much larger than that of other peripheral regions on the anode surface.