High-repetition-rate hydrogen spark gap

The recovery of unblown pressurized gas spark-gaps has been studied in an effort to develop a compact, high-power, high-repetition-rate switch. A two-pulse technique has been used in which the first pulse breaks down the gap and the second is used to determine recovery. For an unblown spark gap triggered near self-break, typical recovery times are about 10 ms for most gases such as air, nitrogen, and SF₆. It was found that using hydrogen gas, with its high thermal diffusivity, allows the recovery time to be an order-of-magnitude faster, or about 1 ms. Recovery of the switch can be made even faster by triggering the switch well below self-break. Recovery time can be decreased by making the operating voltage significantly less than the DC breakdown voltage, allowing voltage to be reapplied while the gas is still hot. Tests with hydrogen have shown that recovery times (to the operating voltage) can be further reduced an order-of-magnitude when the gap is undervolted by approximately 50%. Recent tests have demonstrated 100-ms recovery of an unblown spark gap using high-pressure hydrogen in a trigatron configuration