Trigatron
For example, in the April, 1991 issue (volume 38, Issue 4) of IEEE Transactions on Electron Devices, Stuart Moran and Leonard W. Hardesty from the Naval Surface Warfare Center reviewed their work using a pressurized, unblown hydrogen triggered spark gap (trigatron) with copper-tungsten (Elkonite) main and trigger electrodes. They were easily able to achieve recovery times of ~1 millisecond, and were able to reduce this to 100 usec without forcing gas through the gap. Best results were obtained by undervolting the gap (using ~50% of the self-breakdown voltage) combined with high trigger voltages. Pressures were varied from atmospheric up to 7 MPa (~1000 psig). Although the power levels were MUCH higher than those used in TC's - they were able to achieve 100 usec recovery in a trigatron that handled a 50 kV 170 kA current pulse (12.5 kJ!) by using a trigatron pressurized to 400 psig of H2 - without using flowing gas.
More recent work by a team at the Prather Air Force Research Laboratory (IEEE 12th Pulsed Power Conference, 1999) confirms similar results using a sealed pressurized H2 trigatron. The device can switched 70 Joule pulses at 600 Hz (>40 kW!) with no gas replenishment over a 1 year period.