GB1536513A - Crossed-field switch tube - Google Patents

Abstract

1536513 Cold cathode tubes; arc preventing in switches HUGHES AIRCRAFT CO 20 Jan 1977 [19 Feb 1976 (2)] 02327/77 Headings H1D and H1N In a crossed field switch coaxial tubular anode and cathode define an annular main gap and a tubular control electrode adjacent either anode or cathode defines annular ignition gap, the adjacent anode or cathode being perforated over its whole area to allow the plasma from the ignition gap to enter the main gap (Fig. 3, not shown). Means are provided for producing a magnetic field capable of forming a glow discharge in the main gap, and means for pulsing the control electrode relative to its adjacent main electrode, to which it is anchored via an impedance. The tubular construction may be non-circular, e.g. square with square ring gaps. After evacuation of housing 44 low pressure He is supplied via port 46; an ionization electrode enters at 74, insulated anode 12 and housing-connected squirrel cage (Fig. 2, not shown) cathode 14 are suspended from top plate 50, and control electrode 16 is supported from below. Axial magnetic field is provided by coil 76. To switch on, anode-cathode voltage and magnetic field are applied and control electrode 16 is pulsed (Fig. 5, not shown) relative to cathode, e.g. from a capacitor (Fig. 3, not shown), causing the ignition gap to fire, to supply plasma to cause the main gap to glow sufficiently to pass the current with small anode-cathode drop. Reduction of magnetic field switches OFF (Fig. 4, not shown). A heavy duty switch is preferably provided in parallel.