Experimental investigation of the anode current radial distribution in vacuum arcs

Abstract

The objective of this paper is to determine the radial distribution of the anode current in the high current vacuum arcs under the axial magnetic field(AMF). Based on the specially experimental geometry of a split anode and a butt-type cathode, the currents of the every four divided areas at the anode were measured. In this experiment, four types of the split anode contacts were selected, with the diameters of the central area of 10 mm, 14 mm, 20 mm and 20 mm, respectively. The contact material was CuCr25 (25% Cr). The arc current I ranged from 6 to 14 kA (rms) at 50 Hz. The opening velocity was 2.4 m/s. An external applied uniform AMF was 74 mT. The appearance of the vacuum arcs was recorded by a high-speed charge-coupled device video camera. The experimental results quantitatively reveal the radial distribution of the anode current by the four types split-anode contacts. In our experiments, the current density in the four types split-anode under different geometry was quantitatively measured, which was closely related to the anode current distribution in radial direction. The current density of central area decreased evidently with the increasing of the diameter of the anode central area, which quantitatively indicated that the anode current density concentrated in the central area. The current density of anode central area with the smaller diameter had a higher increasing rate with the increasing of the arc current.