GB1047706A - Improvements in or relating to electrical devices wherein an electric arc may be produced in operation - Google Patents

Abstract

1,047,706. Cold-cathode tubes. GENERAL ELECTRIC CO. Ltd. June 5, 1964 [June 14, 1963], No. 23810/63. Heading H1D. [Also in Division H2] In a discharge tube for use as a switch, at least the cathode of the pair of electrodes between which the controlled current passes includes absorbed hydrogen which, upon initiation of a discharge, is liberated and ionised to provide a high conductance arc, the rapid recombination of the hydrogen ions upon extinction of the arc preventing subsequent undesired reformation of the arc. High-voltage pulses are produced by discharging a bank of capacitors across the electrodes of which one (3, Fig. 1, not shown) may be movable, to permit initiation of the discharge by breaking its contact with the other electrode. Alternatively (Fig. 2, not shown), a control grid 19 and trigger electrode 21 may be provided, a pulse applied between the trigger and the cathode 20 liberating hydrogen ions from the latter, whereby a pulse applied to the grid produces a highcurrent arc between the cathode and the anode 18. The metal and glass envelope is filled with hydrogen, maintained at 100 millitorrs by an electrically heatable source 35, and the electrodes, of titanium, zirconium, or titanium/zirconium alloy, are saturated with hydrogen prior to assembly by heating to 800‹ C. and cooling in hydrogen. The grid, anode, and cathode are provided with coolant tubes, and with baffle plates 28, 24, and 32 respectively, and such liberated hydrogen as is not reabsorbed by the electrodes is removed by the electrically heated getter 12.