A 5-KJ VACUUM CLAMP SWITCH FOR THE PHAROS 2-MJ CAPACITOR BANK.
NAVAL RESEARCH LAB WASHINGTON D C
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A five-kilojoule vacuum clamp switch was developed for Pharos magnetic-compression experiment. Four hundred and twenty of these switches will operate in parallel at full two megajoules as a passive clamp system for the main capacitor bank. The clamp switch is a variation of the Pharos air trigatron starting switch, except that it is housed in a commercial Pyrex tee so that it can be evacuated to one millitorr. The tungsten-copper electrodes with a ten-millimeter gap will hold off the 20-kilovolt bank voltage at this pressure and yet trigger reliably at the low voltage as required. The electrodes, housing, and expansion chamber are assembled with O-ring vacuum seals, allowing rapid interchange or replacement of switch components. The trigger-pin assemblies are identical to those used for the atmospheric-gap starting switches. The clamp-switch terminals, which are an integral part of the electrodes, allow direct mounting across the capacitor high-voltage stud and ground plate. No modification to the existing capacitor bank was required for installation, so the experimental program was not disrupted. Life tests on seven prototype switches showed a reliable life of more than 4000 discharges at five kilojoules per switch. All failures were due to breakage of the Pyrex tee housings. The expected life of all other switch components is many times this. Author
- Electrical and Electronic Equipment
- Plasma Physics and Magnetohydrodynamics