GB1451956A - Travelling wave tubes - Google Patents

Abstract

1451956 Travelling-wave tubes ENGLISH ELECTRIC VALVE CO Ltd 2 Jan 1974 [16 Feb 1973] 7682/73 Heading H1D The fundamental coupled-cavity slow-wave structure of a travelling-wave tube - e.g. a 'centipede' or, as shown, a 'cloverleaf' structure - formed by a stack of alternate slotted plates Y 1 and apertured plates X1, successive X plates being angularly staggeied through 30 degrees, incorporates a periodic permanent magnet focusing system having a polepiece at each nth cavity (where n is greater than unity) provided by forming the appropriate apertured plate and the sandwiching pair of slotted plates, MX and MY, respectively, in, Fig. 3, of soft iron, the apertured plates MX being of enlarged outer density and receiving therebetween axially magnetized ring magnets 3. Fig. 3 shows the case of a polepiece at each fourth cavity. In modified arrangements, the externally projecting periphery of the magnetic apertured plates MX may be of reduced thickness to permit the use of longer ring magnets Fig. 5 (not shown); and the internally projecting portions P, Fig. 2, of the plates MX may be of copper brazed to a common symmetric ferromagnetic annulus Figs. 6 and 7 (not shown). Axial tapering of the structure, by variation of the cell length, or of the aperture or slot dimensions, is referred to.