GB1055580A - Improvements in or relating to electron discharge devices - Google Patents

Abstract

1,055,580. Transit-time tubes. WESTERN ELECTRIC CO. Inc. Nov. 7, 1963 [Nov. 19, 1962], No. 43949/63. Heading H1D. The slow wave structure of an O- or M-type oscillator or amplifier is in the form of a serpentine-shaped dual conductor transmission line, e.g. a coaxial cable, having conductive vanes attached to one of the conductors at periodic spatial intervals, such vane extending through an opening in the second conductor to a point in proximity to the electron stream path. The coaxial cable delay line 14 of a crossed-field forward wave amplifier, Figs. and 2, is folded into serpentine shape and formed into a cylinder surrounding, and maintained at a positive potential with respect to, a cylindrical cathode 12. An axial magnetic field is provided by polepieces 15 and 16, connected by the soft iron envelope 17, and a conductive vane 21 projects from the inner coaxial conductor 19, at the centre of each reach of the serpentine, through a corresponding slot in the outer conductor 21, to couple with the electron stream moving round the cathode. To facilitate cooling, the inner conductor 19 may be connected to the outer conductor 20 at each end of each reach (Fig. 7, not shown), to provide a heat sink, adjacent reaches being coupled by apertures in the outer conductor, or by quarter wavelength stubs (Fig. 9, not shown). Additional cooling may be obtained by using a hollow inner conductor 19 through which coolant is pumped (Fig. 8, not shown). In a linear crossed-field backward wave oscillator, Fig. 10, the electron stream passes from cathode 37 past the plane, coaxial cable. slow-wave structure 35, to collector 38, through the magnetic field B and an electrostatic field maintained between the slow-wave structure and the electrode 36. Effective backward wave coupling is introduced by the provision of additional vanes 44 attached to the outer coaxial conductor 41 between each pair of adjacent reaches of the serpentine. Construction in a circular form, as in Fig. 7, is also referred to. In the forward wave amplifier of Fig. 11, an electron stream passing from cathode 46 to collector 47 is focused by a parallel magnetic field B, and passes through apertures 52 formed in the vane of 51. The addition of interposing vanes as 44 of Fig. 10, would produce a backward wave device. In an alternative form of the construction of Fig. 11, the serpentine slow wave structure could be wound helically around the electron stream.