GB909558A - Improvements in or relating to velocity modulated electron tubes - Google Patents

Abstract

909,558. Velocity modulated tubes. CSF. COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL. Jan. 27, 1961 [Feb. 25, 1960], No. 3219/61. Class 39 (1). In a velocity modulated tube, e.g. a klystron or travelling wave tube, the collector comprises a plurality of metal elements 9, Fig. 1, bounding a frustoconical space, whose axis is inclined to the beam axis, means in the collector space for decelerating the electron beam and a magnetic field in the collector space which has decreasing intensities from the smaller to the larger cross-section of the collector so that the electrons move in a helix of increasing radius and impinge on the metal elements 9. The electrostatic field causes reflected and secondary emitted electrons to return off the axis so that they are less likely to re-enter the resonator system. In one form, Fig. 1, there are four separate annular magnetic coils around an array of annular collector flat slanted rings 9 forming the envelope of a cone and closed at the large end by an inclined flat plate 12. The plate 12 is at cathode potential and collector rings are at graded potentials between this potential and the potential of the block 2 housing the four resonators which is at a high positive potential. The magnetic coils have decreasing numbers of turns in the direction of the beam so that the magnetic field decreases in intensity in this direction. If the coils are identical and of successively decreasing currents, the internal surfaces of the collector rings 9 may have paddles or fins, to improve collection, and inclined to the radial, Fig. 4 (not shown). In a modification, the centre of the collector rings may be disposed along a curve. In another modification, Fig. 5 (not shown), perforated discs are used for the collector elements. Paddles or fins may also be used in this embodiment inclined to the lateral surfaces. In another modification, Fig. 6 (not shown), the resonator body has a projection to incline the E.S. field. The collector rings have liquid cooling by making the rings of Fig. 1 and similar embodiments hollow, or over them if the members are flat perforated discs as in Fig. 5.