COUPLED CAVITY SLOW WAVE CIRCUIT AND TUBE USING SAME

1361833 Velocity-modulated tubes VARIAN ASSOCIATES 3 Sept 1971 [8 Sept 1970] 41144/71 Heading H1D In a coupled-cavity slow-wave structure, for a travelling-wave tube or a hybrid tube, in which the coupling slots are arranged in a plurality of N axially aligned arrays, with N greater than 2-, e.g. a cloverleaf structure-at least N of the cavity end walls have less than the full number of full-sized slots, and these end walls are so angularly disposed as to block off at least a portion of the line-of-sight path through each of the axial arrays, and thereby prevent undesired beamlets in the slot arrays interacting cumulatively with the fields in the slow-wave-structure. Preferably, each of these end walls lacks only one full-sized slot, the place of which is taken by a slot extending over only the radially outer half of the normal slot length, whereby the inner half, through which most of the beamlet passes, is blocked off. In a severed, forward-wave travelling-wave tube, the upstream end section, in which the field intensities are least, may be of normal construction. The slow-wave structure may be assembled by sliding the cavity members on to a set of aligning rods which pass through spaced holes adjacent the peripheries of the members (Fig. 3, not shown).