Some Recent Advances in Three Electrode Field Enhanced Triggered Gas Switches
The field distortion gap is a spark gap with a third (trigger) electrode having a sharp edge. The trigger electrode creates a high field at the edge, producing rapid breakdown. Gas spark gaps employing this principle have been widely used. Several recent advances are described which represent important progress in switch technology.
A dc-charged rail switch 1.8 meters in length with an inductance of 1.7 nH ± 2 percent has been developed. It approaches the performance levels hitherto available only with single shot solid dielectric switches. This has been used at a maximum voltage of 60 kV, to discharge a 55 kJ capacitor bank at currents up to 1.5 MA, with over 4 coulombs flowing in the switch. Typically about 15 channels are created over an operating range of over 3:1 in voltage.
The rail switch performance was achieved with a newly discovered gas mixture which gives much improved multiple channel breakdown characteristics and a wider triggering range. Two other switches are described that have utilized this mixture. One is an air-insulated 6 nH rail gap pulse charged up to 130 kV in 2 to 3 μsec. This switch carries 500 kA and 1 Cb. The other is a dc-charged single channel,26 nH switch operable from 20 to 60 kV. This gap may be triggered down to 35 percent of self breakdown with a jitter of only a few nanoseconds.
KeywordsBreakdown Voltage Sulfur Hexafluoride Percent Sulfur Main Electrode Breakdown Channel
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