GB715242A - Improvement in adjustable magnetic focussing system for beam tubes - Google Patents

Abstract

715,242. Electron beam apparatus. SPERRY CORPORATION. July 16, 1952 [July 16, 1951], No. 18052/52. Class 39(1) An electron discharge apparatus, such as a klystron or travelling wave tube, has two pole pieces 41, 43, Fig. 1, forming part of the tube envelope and traversed by the beam, and two soft iron magnetic coupling rings 47, 49 connected to the opposite ends of a permanent magnet 45, the rings 47, 49 and polepieces 41, 43 being relatively adjustable in planes perpendicular to the beam, preferably by means of two sets of three or more adjusting screws, Fig. 2 (not shown). This arrangement compensates for undesired asymmetries in the magnetic field due to the asymmetrical disposition of the magnet, misalignment of drift tubes 27, 29 between cavity resonators 17, 19, 21, and of the electron gun, presence of ferrous alloys in the individual resonator tuning units such as 31, 33, 35 and in the input or output couplings, or partial saturation or non-uniform flux density in the pole pieces 41, 43. Each ring 47, 49 comprises two semicircular parts mortised and pinned together at one meeting point and making a butt joint adjacent to the flat surfaces of contact with the magnet 45, Fig. 2 (not shown). Rings 47, 49 are screwed to brass spacer 67 attached to two plates 69 secured to magnet 45 at 77. The magnet system is preferably mounted rigidly, and magnet 45 may be of bar or U-shape. The tube has three cavity resonators 17, 19, 21 and hollow collector 23, and 25 and 41 serves as the final gun anode, 17 is the input resonator and 19, 21 give a low and high power output respectively; the resonators are individually tuned as by piston 31 actuated by screw 35 through bellows 33. The tuning units may be all similarly constructed and be at different angular positions. The energy coupling may be to or from coaxial lines for 17, 19 and to a wave guide for 21.