GB554851A - Electron discharge apparatus - Google Patents

Abstract

554,851. Thermionic valves and circuits therefor ; electron multipliers. STANDARD TELEPHONES & CABLES, Ltd. (Western Electric Co., Inc.). March 28, 1942, No. 4173. [Classes 39 (i) and 40 (v)] In an electron discharge device a plane surface cathode 14, Fig. 2-which may be thermionic or photo-electric-is used with a control grid 15 coplanar with the cathode ; a screen electrode 16 at cathode potential is arranged beyond the grid and an accelerating electrode 21 surrounds the grid and screen. On the side of grid remote from the emissive surface of the cathode is arranged a target electrode 19, which may be the output anode or the first or only secondary emitting electrode of an electron multiplier with output 20. An electromagnet 22 together with the field due to the electrode 21 constrains electrons from the cathode to follow a curved path ; with the grid at cathode potential the electrons flow to the screen 16 and accelerator, but if the grid swings positive due to an incoming signal through transformer T<SP>1</SP>, part of the electron stream flows to the target 19. The arrangement shown is for use as an amplifier but the device may be used as an oscillation generator or detector. A directly heated ribbon cathode may be used. In a modification acting as a push-pull amplifier the cathode 14a, Fig. 3, has emitting material on each surface and on each side thereof, a control grid 15a, 15b, screens 16a, 16b, an accelerating electrode 21a, 21b, and a target or output anode 19a, 19b. An electromagnet, not shown, causes electron flow in curved paths. The two targets are connected together and to a blocking condenser 30a, and the two accelerators which also act as output anodes are connected to a condenser 30b. Biasing potentials are provided by the source 31, through resistance 33 to the four anodes. An output circuit may be connected across the resistances 34a, 34b, whose junction point is grounded. According to the potential of the grids current flow is to the targets or to the accelerator anodes.