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

The paper studies the voltage-current characteristics of six-gap rod electrode system versus shape and material of the electrodes and inter-electrode gap value for triggered vacuum switches. The investigations were carried out at a current amplitude up to 200 kA with the rate of its rise up to ~5·10⁹ 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 high frequency voltage oscillations in the discharge current wave front. The duration and intensity of the unstable discharge burning phase accompanied by frequency voltage oscillations depend strongly on electrode system parameters. Dynamic power dissipated in the vacuum gaps and full dissipated energy were calculated in terms of the switching current amplitude. Results of the investigations gave possibility to design a sealed-off triggered vacuum switch having minimum power losses and prolonged service life evaluated by a transferred charge value >10⁶ C