Patent GB-729766-A (GB)
Title: Improvements in electron velocity modulation tubes
Inventor: BECK ARNOLD HUGH WILLIAM
IPC: H01J25/11
Filed: 1952-08-01
Abstract: 729,766. Velocity-modulated tubes. STANDARD TELEPHONES & CABLES, Ltd. Aug. 1, 1952, No. 19515/52. Class 39 (1). A two-resonator klystron amplifier tube comprises cylindrical input and output resonators positioned end to end along a common axis; a series of drift tubes mounted end to end along the length of the said common axis and separated from one another by gaps, one of the said drift tubes communicating between the input and output resonators and the remainder being intermediate the ends of the respective resonators; means for projecting a beam of electrons through the said series of drift tubes, the said gaps between successive drift tubes being of such length that the transit angle of an unmodulated electron of the said beam in each said gap is 2# radians; and respective coupling means for injecting electromagnetic wave energy into the input resonator and for extracting electromagnetic wave energy from the output resonator. In the arrangement shown the resonators are formed by a single copper block having an outer wall 1 and divided by a transverse wall 2. End plates 3 and 4 are bonded to the wall 1 by, for example, a gold diffusion process. A drift tube 6 is integral with, or secured in a central aperture of, the dividing wall 2 and further drift tubes 5 are secured to the wall 1 by rods (not shown) preferably made of copper-plated tungsten, the rods securing adjacent drift tubes being located on opposite sides of the axis of the resonators to reduce the capacitance between drift tubes. Two cups 9 and 10 of magnetic material, secured in central apertures of the end plates 3 and 4, house an electron gun and a collector electrode 18 respectively, and form pole pieces for a focusing magnet (not shown) which completes a focusing system as described in Specification 674,758. Cups 9 and 10 are provided with portions 19 which form continuations of the series of drift tubes 5. Input and output connections to the respective resonators are provided by sections 20 and 21 of rectangular wave-guide, let into the wall 1 and secured by means of a metal cylinder 23. The wave-guide sections terminate in a flange 24 to which are secured two tuned diaphragms 25 and 26 provided with glass windows 27. Tuning of the resonators is accomplished by means of a mechanism of the type described in Specification 668,508, [Group XL (b)], comprising tuning strips 28 having sides mounted in trunnions 29 free to rotate in the wall 1 and spring fingers 30 which contact the end surfaces of the respective resonators. The strips 28 are secured to piston rods 31 or 32 secured respectively to the base members 33 and 34 of a pair of metal bellows 35 and 36 the other ends of which are secured to the outer surface of the cylinder 23. Ducts 41 in the wall 1 and cylinder 23 are provided for evacuating the interior of the bellows. The base member 34 of bellows 36 is secured by means of a nut and a threaded rod 47 to a cross piece 44 which slides in guides 45 and 46 in supporting members 42 and 43. The base member 33 of bellows 35 is provided with a screwed rod 48 free to move axially in the cross member 44'under control of a knurled nut 49. The cross member 44 carries a screwed rod 50 engaging with an axial extension 51 of a knurled nut 53 which is free to rotate in an end plate 52 joining the ends of the members 42 and 43. The knurled nut 53 controls the position of the cross member 44 to provide simultaneous adjustment of the tuning strips 28, while adjustment of the nut 49 provides for differential tuning of the resonators.