GB1162392A - Vacuum Gap Devices for High Temperature Operation - Google Patents

Abstract

1,162,392. Cold cathode tubes. GENERAL ELECTRIC CO. 27 Sept., 1966 [28 Dec., 1965] No. 43163/66. Heading H1D A triggerable vacuum gap discharge device suitable for use at high temperatures includes a pair of primary arc electrodes which are free of gas or gas-producing impurities to the extent that, subsequent to reabsorption of plasma ions after arcing, the pressure does not rise above 10<SP>-5</SP> torr, one of the primary electrodes including a cavity opening into the gap therebetween and housing a trigger assembly formed by a pair of spaced metal members one of which is connected to the primary electrode; the metal members of the trigger assembly serve, upon the establishment of an arc between them, as a source of ionised metal vapour for injection into the primary gap. The trigger gap 20 is formed by a groove cut through a metallic coating 18, 19 formed on the surface of the insulator 4 which projects through a cylindrical aperture into the conical opening 10 in the main cathode 6. Connection is made to layer 19 via a lead 12 and the plate 11, layer 18 being connected to the main cathode 6. Cathode 6 and anode 7 of the main gap are supported by metal terminal discs 5 and 3, respectively, which are sealed to alumina ceramic envelope portions 1 and 2, the latter being shielded from condensed metal vapour by electrode 14. The main electrodes are of the copper, beryllium, or alloys thereof, and the layers 18, 19 either of the same material, or of aluminium, iron, nickel, cobalt, lead, or beryllium tin. Upon the application of a trigger pulse across the gap 20, metal from layers 18 and 19 is vaporized and ionised, and projected by the magnetic field of the discharge into the main gap between electrodes 6 and 7. To ensure a copious supply of metal vapour, the conical portion of electrode 6 is also provided with a similar metallic layer 21. In a modified arrangement (Fig. 3, not shown), the trigger gap is protected from the main discharge by an overhanging portion of the wall of cathode 6.