Patent GB-496973-A (GB)
Title: Electron discharge devices
IPC: H01J19/34
Filed: 1937-07-02
Abstract: 496,973. Thermionic valves; leading-in conductors. STANDARD TELEPHONES & CABLES, Ltd. July 2, 1937, No. 18434. Convention date, July 3, 1936. [Class 39 (i)] [Also in Group XI] In high power electron-discharge devices of the water-cooled or external anode type, a cylindrical metallic portion serving as anode has vitreous portions with re-entrant stems sealed to opposite ends, a cathode assembly is supported at each end on the stems and a cylindrical grid structure is coaxially arranged between the cathode and anode and supported at each end by the vitreous portions at parts intermediate the ends of the anodes and the stems. The discharge device, Fig. 1, comprises a cylindrical metal anode 20 surrounded by an integral metallic cooling jacket 21 and having two vitreous extension portions 22, 23 hermetically sealed to opposite ends of the anode. The extension 22 is provided with a re-entrant steam 24 to the inside of which is sealed the flared edge of a moulded dish-like member 26, having six tubular sleeves 27 projecting outwardly and each provided with a metallic terminal consisting of a seal to which is attached flexible lead 31 and a rigid metallic conductor 32, Fig. 3, which is sealed to the end of a filament strand, there being three looped filament strands, the six ends of which are thus connected to the leads 31. The conductors 32 pass through apertures in two discs 41 arranged in a metal shield 40, the apertures being provided with metallic bushings which permit free sliding movement of the conductors 32 and the loops of the filaments 39, Fig. 11, are provided with loose helical spring spacers 47 where they pass over sheaves 48 attached to shielding plates 49 each attached to a rigid rod 50, Fig. 4, which passes freely through an aperture in spaced discs 52 arranged in a shielding tube 51, mounted in a re-entrant stem portion 34 of the vitreous end member 23 of the discharge tube. The rods 50 are attached to tension springs 53 attached to a sliding plate 54 and the tension is controlled by an adjusting bolt 56. The filaments are prevented from bowing by connecting them in sets of three by means of triangular wire members arranged round the filaments and' engaging notches therein. The grid consists of a helical wire, carried by longitudinally arranged rods 63, the upper ends of which are bent into a U- shape and passed through apertures in the flanged end of a conical glass members 68 sealed to the wall of the end member 22, the rods being locked in position by nuts engaging thin screw-threaded ends. The lower ends of the rods pass freely through apertures formed in a similar glass member 69 sealed to the wall of the end member 23. The arrangement of filament and grid permits free thermal expansion of these members; in assembly the filament and grid units are separately assembled, the grid is located in the anode unit and locked thereto by means of the supporting members 68, 69 and the cathode unit is then threaded through one end of the vessel, passing through a guide sleeve 35 and being fixed at its lower end by bolts 59, engaging a metallic member 38 attached to the re-entrant stem 37 of the member 23. The tension is adjusted and the member 26 is sealed to the re-entrant stem 24, whereupon the vessel is exhausted through a stem 36 and scaled off. In a modification, the upper ends of the grid supports 63 are sealed in a metallic collar attached to a sleeve which surrounds the sleeve 40 and is attached to a metallic member 25 sealed to the re-entrant stem 24. In addition the lower ends of the rods 97, Fig. 17, which are attached to the filament sheaves 98 are attached to a cup 96 which is fixed to a rod 94 actuated by a compression spring 92 mounted in a sleeve 89 which is supported in a re-entrant part 83 of the glass end 23 by a metal cap 84 and a frame consisting of two plate members 85, 88 and connecting rods 86. In this arrangement, the ends of the grid supporting rods 63 slide in bushed openings 79 of a dished member 80 sealed to the sides of the glass end 23.