Experimental investigation of high current vacuum arc under non-uniformly distributed axial magnetic field

In this paper, the behavior of high current vacuum arc under axial magnetic field (AMF) with different radial distributions, e.g., saddle shaped AMF and bell shaped AMF, are investigated. The different AMF distributions are implemented by adding ferromagnetic material (iron) into existing cup-shaped AMF electrodes. High current experiments have been conducted with these iron-style AMF electrodes. Images of the vacuum arc column and the distribution of cathode spots were photographed with a high-speed charge coupled device (CCD) camera. Experimental results indicate that non-uniformly distributed AMF with higher axial magnetic flux density at the contact periphery than that at the center (saddle shaped AMF) can resist arc constriction and increase the cathode and anode utilization ratios more effectively than ordinary bell shaped AMF profile.