A Compact, Multiple Channel 3 MV Gas Switch
A triggered, pressurized sulfur hexafluoride spark gap has been developed in which multiple parallel spark channels are consistently generated in close proximity to each other. In a test in which the switch drove a 60 ohm, 20 nsec pulse line, an average of four to six channels were created within a diameter of about 3 inches. Each channel was about 3.5 inches long in 175 psig SF6, and the total switch inductance was in the region of 90 nH. Triggering is effected by a field-enhanced electrode placed close to the ground electrode, a configuration known as the V/N switch. The trigger voltage at 3 MV pulse charge is 250 kV. The rms jitter of the switch breakdown is less than 1 nsec. It is expected that the high performance (low jitter obtained with a small ratio of trigger voltage to total voltage) will scale to much higher voltages. The switch used in the developmental tests was designed for oil immersion, and possessed a further novel feature, a pressure vessel that can withstand high electrical stress with good reliability. The pressure wall achieves this performance through the use of a segmented design, and withstood up to 3.75 MV over a total distance of about 8.5 inches.
KeywordsGround Electrode Trigger Pulse Marx Generator Breakdown Time Sandia Laboratory
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