Effects of Atmosphere on the Evolution Process of Graphite Electrodes under the Pulsed Discharge

Graphite electrodes has been widely used in high transfer coulomb gap switches because of its excellent ablation resistance. When the arc temperature exceeds the boiling point of graphite, it will sublimate as the gaseous graphite. Gaseous graphite is oxidized the oxygen in switch chamber to form carbon oxides, and the incomplete oxidized part of the sublimation will condense into solid carbon in an enclosed chamber. The multiple repeated discharge will result in the severe electrode erosion. In order to increase the service life of the electrode, a new type of gas mixture was used to replace the original air as the insulating medium in the study. It is found that the erosion in argon-oxygen mixture is weaker than air under the impact of an intense pulsed arc, which can protect the electrode surface and prolong the service life of the electrode.