GB437167A - Improvements in or connected with electric discharge devices - Google Patents

Abstract

437,167. Discharge apparatus. STANDARD TELEPHONES & CABLES, Ltd., 63, Aldwych, London.-(Assignees of Rockwood, G. H. ; 563, Argyle Avenue, Orange, New Jersey, U.S.A.) March 15, 1935, No. 8157. Convention date, Oct. 3, 1934. [Class 39 (i)] A gas-filled device comprises a cathode, a plurality of electrically separate anodes upon which separate discharge paths ter minate and a control grid between the cathode and the anodes, and the arrangement is such that the breakdown characteristic is different for each anode. In one form, a cathode 16 is surrounded by a cylindrical control grid 24 supported on a rod 23 and having apertures 28, 29 facing rod anodes 30, 31, the lower portions of which are covered with glass tubes 32. The aperture 28 is larger than the aperture 29 and the anode 30 is nearer the cathode than the anode 31. The control-grid may " trigger " the discharge to anode 30, which in turn initiates the discharge to anode 31. The device may be filled with argon at a pressure of 0.25 mm. The rod anodes may support mica spacing discs above and below the electrode structure. An additional negatively-biassed helical grid may be inserted between the cathode and the controlgrid. A metallic shield may surround the cathode heater leads. The ends of the rod anodes may be bent towards the apertures in the control-grid. In a modification the controlgrid is a helical wire surrounding a filamentary cathode. Two rods are sealed into the pinch outside and in line with the grid posts, and one serves as an anode whilst the other carries an arm to which is welded a rod-anode adjacent the middle of the control-grid. In another modification for full-wave rectification an indirectly heated cathode is surrounded by a control-grid and by two coaxial anodes, and a short rod-anode positioned outside this electrode structure serves to initiate the discharge.