GB922113A - Travelling wave amplifier tube - Google Patents

Abstract

922,113. Travelling-wave tubes. RADIO CORPORATION OF AMERICA. July 22, 1959 [Aug. 5, 1958], No. 25213/59. Class 39 (1). A travelling-wave tube has a number of radially-cut discs 56, Fig. 2a, arranged within a conductive tube 20, Fig. 1, so as to form a number of comb-like delay lines extending axially along the tube and spaced circumferentially. An electron beam is caused to travel helically around a central conductor 36 so that individual electrons interact successively with teeth of circumferentially-adjacent combs. Intermediate discs 62, Fig. 3a, are arranged between each disc 56 and are provided with short projections 64 which bring the axial combs into the propagating condition (radial depth of slots #/4 or less) while leaving the lines formed by each circumferential set of teeth in a non-propagating condition (radial depth of slots between #/4 and #/2). Thus by a suitable input circuit 49 waves may be launched on each comb which are in opposition on adjacent combs and do not exchange energy circumferentially. The electrons, however, in space-harmonic fashion, see a synchronously-travelling wave at each tooth traversed in their helical path and give up energy to the waves for delivery to output circuit 55. The combs may alternatively extend outwardly from the central conductor and the beam then travels outside them. The input circuit consists in a cavity 49 fed by line 48 and one wall of which consists in a disc 50, Fig. 5a, with half the number of teeth so that only alternate combs are excited in phase; the output circuit 55 is similar. Choke slots 70 prevent leakage into the gun region. Cathode 24, positive grid 28, and anode 34, in conjunction with lower voltage central conductor 32 produce the annular helically-moving beam 22, which is finally collected by collector 18. The central conductor 36 is supported on conductor 32 and on rod 46 slidably engaging the collector 18.