Recovery of the insulating property of a vacuum gap after breakdown caused by a 4.5  sec pulse

Following breakdown caused by a 4.5 μsec pulse, a second 4.5 μsec pulse of variable amplitude was used to investigate the recovery of the gap during the period from 5 to 400 μsec after breakdown. Recovery curves are presented for normal and overvoltage breakdown. They show that the gap recovers at a rate of the order of 10 kv μsec -1 during the first 5 μsec or so, and at 0.01 kv μsec -1 after about 100 μsec. To explain the incomplete recovery after such long periods it is suggested that charged particles from the discharge channel reside on suitable insulating sites on the electrode surfaces and lead to discharge initiation when a sufficiently high field is next applied.