GB1458252A - Vacuum arc discharge device - Google Patents

Abstract

1458252 Cold-cathode tubes; vacuum switches GENERAL ELECTRIC CO 28 Feb 1974 [2 April 1973] 9061/74 Headings H1D and H1N A vacuum arc discharge device comprises two circular arrays of parallel cylindrical coaxially aligned primary arc electrodes 16 and 18 supported in a sealed envelope by end plates 15 and 17, and an intermediate circular array of parallel electrodes 19 supported by an intermediate plate 13 which divides the envelope 11 into two regions A and B, and means 22, 23 for causing an arc breakdown between adjacent electrodes in each region A and B, the intermediate electrodes 19 being interdigitated with the primary electrodes 16 and 18 so that in operation adjacent electrodes are of opposite polarity and the magnetic force acting on current paths is minimized, thus minimizing the formation of destructive anode spots. The presence of two inter-electrode gaps in series in each conduction path between the terminals 43 and 44 of the device increases the hold-off capacity. Shield members 26 protect the insulating side walls 12 of the device from the deposition of metallic particles from the electrodes. In the device shown the arc initiating means comprise butt-type mating contacts 22, 23 mounted on a rod 36 and rods 33 sealed through bellows 34 protected by shields 35. In an alternative device (Fig. 3, not shown) the regions A and B are in communication through an aperture in the central plate 13 and the arc initiating means comprise a trigger electrode in one or both of the regions for injecting plasma into the inter-electrode gaps. In a further alternative device (Fig. 5, not shown) a trigger electrode is mounted in a bore communicating with the aperture in the central plate to inject plasma into both regions A and B.