Reignition phenomena after high-frequency current interruption in vacuum at small contact gaps

Based on a large number of measurements of high-frequency (HF) current interruptions in a vacuum at small contact gap (/spl les/600 /spl mu/m) the statistical reignition behaviour of vacuum switching devices after a HF current zero is investigated. Three types of reignitions can be classified. Statistical evaluation of post arc current measurements for different parameters at current zero, i.e. ignition of the HF current, current steepness and gap distance gives information about the stress of the gap as a result of the transient recovery voltage after a HF current zero (HF-TRV) and the accumulated post arc charge. Comparing post arc current values at the beginning of the HF-TRV and at the moment of reignition reveals a production of charge carriers during the recovery interval. Possible reasons for the different types of reignitions are discussed.