GB672978A - Improvements in and relating to electric discharge devices - Google Patents

Abstract

672,978. Thermionic valves. BRITISH THOMSON-HOUSTON CO., Ltd. April 19, 1949 [April 19, 1948], No. 10353/49. Class 39 (i). An electric discharge device having substantially planar apertured shield members 25, 26 arranged respectively between a cathode and a control grid 34, and the control grid and a substantially planar anode 24, the shield member, control grid and anode being clamped together by a fastening means and held by a common supporting means through the intermediary of insulating spacer elements 32, has a substantially planar and conductive additional shield member 27 joined to the shield 26 and positioned on the opposite side of the anode from shield 26. The shield members may be cup-shaped, two of them, 26, 27, having their cylindrical flanges extending in'the same direction and bonded together, and the third, 25, having its cylindrical flange extending in the opposite direction. The grid 34 may have a depending flange 36 for cooling and resilient members 42 are attached to the flange and serve to space the grid from the envelope. The electrode assembly is supported from three support rods, of which two, 28, 29, are shown; support 28 makes an electrical connection to shields 26 and 27, support 29 is connected to shield 25, and the third support is connected to the control grid 34. These support-rods extend to a header 2 which also supports the cathode structure ; a conductor for the anode is sealed through the other end of the envelope. The ends of the cathode are connected to a common terminal and the mid-point of the cathode is connected to another terminal; resistances 52, 53 are connected between these terminals and lead-in conductor 8 which is connected to support-rod 29 so that shield 25 is kept at mid-cathode potential. The gas filling may be of xenon at 100-150 Á pressure.