A 500k kA high-voltage vacuum switch

The development of a novel high-voltage high-current vacuum closing switch is described. For many decades the standard switch for industrial high-volt age high-current switching applications has been the mercury cathode ignitr on. However; these devices suffer from poor voltage reliability, particular ly in high-current applications and contain mercury, which is undesirable f or environmental reasons. The emergence of several demanding pulsed-power a pplications for which ignitrons are not suitable has driven the development described The objective of the development was to produce a switch capable of operation at 24kV, 500kA and 130C per shot using environmentally-accept able materials whilst retaining the beneficial characteristics of ignitrons such as wide operating voltage range and rugged, simple design. Any design capable of meeting these objectives would also be capable of forming the b asis of an ignitron replacement at lower voltage and current levels. An ini tial phase of technology selection was performed, following which a vacuum switch option was pursued. The subsequent development of the switch design is described and test results at the target specification levels are given.