Vacuum-Arc Anode Phenomena: New Findings and New Applications

The vacuum arc modes from the viewpoint of anode activity have traditionally been considered as a diffuse arc, footpoints, anode spots, and an intense arc. Recent studies carried out jointly by the IHCE SB RAS and the INP-Greifswald have made it possible to identify anodic plume and anode spot type 2 as new modes of a high-current vacuum arc, specific for electrodes made of a copper-chromium composition. The anode plume appears either immediately before the anode spot of type 2, or immediately after the extinction of the anode spot of type 2. The appearance of the plume before the spot is unstable, while after the spot the plume is stable. Appearance of the plume is an indicator of the intense vapor flux of the anode material, which can reduce the breaking capacity of the vacuum circuit breaker (VCB). Implementation of the VCB operating mode free of both the anode spot type 2 and anode plume allows a more successful recovering of the electric strength of the VCB after current zero.