GB766007A - Improvements in or relating to travelling wave tubes - Google Patents

Abstract

766,007. Travelling-wave tubes. STANDARD TELEPHONES & CABLES, Ltd. Oct. 14, 1953, No. 28270/53. Class 39(1). A travelling-wave tube comprises a helix 6, Fig. 1, carried within and by a tube of insulating material 7 which is supported at at each end on sleeves 8, 9 at least one of which is an inner choke sleeve member, the sleeve member 8 at the gun end of the tube being mounted on or forming part of the gun. In Fig. 1, wire helix 6 is carried by tube 7 of insulating material mounted at either end on sleeve members 8, 9, the outer portions 17 of which form the inner portions of waveguide chokes. Lorry material is pointed or evaporated on the inside or outside of tube 7, and impedence matching pistons 14 are provided. The ends of the helix 6 are connected via wire frobes 20 to bosses 18, 19 of sleeve members 8, 9. Sleeve member 8 is carried by a metal tube 21 secured to gun anode 22 or to insulating washer 26. The cathode 23, focussing cylinder 24 and anode 22 are supported by rods 25 and insulating washers one of which is 26. The collector 4 has a locating step 29 for insulating tube 30 supporting sleeve 9 so that in manufacture the gun, helix and sleeve assembly can be inserted as a unit into the envelope until tube 30 seats on step 29. The beam is focussed by an assembly of coils (not shown). In another embodiment, Fig. 2, the gun is surrounded by pole piece 35 which supports the anode from its front surface and also serves as an inner waveguide choke member, and sleeve 41 similarly serves as a second pole piece and choke member. Members 35, 41 carry the helix support tube 42 by means of bosses 43, 44. The ends of the helix are brought out from tube 42 through slots 46 and connected to U-shaped probes 47 which are as described in Specification 755,834. Three ceramic rods 48 have sleeves at their ends having flanges 49 which are welded to members 35, 41 to form a rigid assembly. Collector 38 has cooling fins 39 and a metal evacuating tube 40 which also provides the locating surface and support for the unitary gun-helix electrode assembly. 52, 54 are outer pole piece members of copper plated ferromagnetic material and also serve as outer choke members. 54 is - #/4 long and 52 has a portion of relatively small bore long and a further portion 53 of larger bore. The portion 53 together with the gun form an open circuited line of comparatively high impedance so that little energy escapes. The pole piece member 52 may butt against the guide wall, as shown, or the guide wall can be cut away so that the end surface of 52 is flush with the inner surface of the guide. Additional chokes 55, 57, 56, 58, and pairs of short circuiting rods 61, 62 cooperating with, matching guide sections 59, 60 are provided. The tube may be used as an amplifier, oscillator or frequency changer. Specification 762,106 also is referred to.