Patent GB-854584-A (GB)
Title: Improvements in or relating to electron discharge devices of the reflex klystron type
IPC: H01J25/24
Filed: 1959-05-01
Abstract: 854,584. Velocity modulated tubes. WESTERN ELECTRIC CO. Inc. May 1, 1959 [May 5, 1958], No. 14899/59. Class 39(1). A reflex klystron has a cup-shaped member 11, 12 surrounding the cathode the gun anode 38 being mounted in an aperture in the cup base, a hollow cylindrical window 27 sealed to annular port 12 and means for relieving stress at the seal 12-27 comprising hollow cylinder 50 bonded to 12 and of the same size shape and material as 27, the gun cathode being mounted from and extending within 50. The members 27, 50 are both of ceramic material. The ceramic cylinder 50 is preferably of the same intemal and external diameters, length and material as ceramic window 27 (preferably of ceramic having a high alumina content) and the envelope parts 14; 11,12; 28, and 35 being of "Hovar" (Registered Trade Mark) while reflector support 36 is of ceramic material ; gun anode 38 is of copper. The cathode 59 has a spherical emissive surface 61 and a heater 62 the leads to which have U-shaped bend connectors 65 passing through a ceramic disc 63. A metal heater shield of cupshape has crimped tabs 43 around ceramic disc 63 and together with the cathode is surrounded by metal cathode heat shield 58 which anchors the cathode 59 by bent wires 60 brazed to the parts. A corrugated cylinder 53 allows adjustment of the gun anode-beam forming electrode 56 distance during manufacture. The resonator grids 31, 42 are carried from metal envelope disc 28 and frusto-conical gun anode 38 ; beam forming electrode 56 is also frusto-conical and has a frusto-conical interior aperture sloping in the same sense. The envelope base is a platform 16 with a ring of terminals comprising ceramic insulators 18, metal eyelet plates 19 and vitreous sealing beads (not shown) within 18 through which terminal pins 20 pass. The exhaust tube 24 is carried by ceramic bushing 22 and metal washer 23 having a projection 25, an annular glass sealing bead filling the space defined by members 23, 22 and 16. The projections 25 is connected via lead 47 to one end of getter 26 the return lead being a pin 20 ; the getter 26 can thus be flashed during manufacture. Members (reflector assembly) 33, 36, 28 are positioned by jigs as are 50, 57, 53, 55 (cathodebeam forming electrode assembly) to get the beam forming electrode correctly spaced from the cathode. In manufacture all parts except the base cathode 59 and cathode shield 58 are assembled in one operation and baked, the remaining parts being assembled outside the tube, baked put into the envelope and fixed and sealed where necessary, e.g. cathode shield 58, cathode 59 are positioned by jigs. Cylinder 58 is the cathode-beam forming electrode spacer as well as a cathode shield. During assembly the spacing between the resonator grids is set by measurement or the tube is mounted in a standard cavity resonator and the grid spacing adjusted, after which the beam forming gun-anode distance is set by deforming 53. Metal cylinder 55 and beam forming electrode 56 may be integral. The envelope seals and internal parts are welded or brazed together, e.g. 52 is welded or brazed to 51. The ceramic members 27, 50 are sealed to 12 by a standard ceramic metal sealing technique. Modulating signals may be applied to the reflector.