The burning voltage of a high-current vacuum arc in a six-cap rod electrode system

This paper studies the voltage-current characteristics of the six-gap rod electrode system and their dependence on the shape and material of the electrodes and interelectrode gap value. The investigations were carried out for currents up to 200 kA with the rate of its rise up to /spl sim/5/spl middot/10/sup 9/ A/s. A number of features were observed concerning arc-burning voltage dynamics depending on the value and rate of rise of the arc current, namely, a step-like voltage change at an initial discharge burning stage, and excitation of HF voltage oscillations for the discharge current wavefront. The duration and intensity of the unstable discharge burning phase accompanied by HF voltage oscillations depend strongly on the electrode system parameters. Power dissipated in the vacuum gaps and full dissipated energy were calculated as a function of the switching current peak. Results of the investigations give the possibility of designing a sealed-off triggered vacuum switch with minimum power losses and long service life evaluated by a transferred charge value >10/sup 6/ C.