GB577530A - Improvements in or relating to electron discharge devices employing hollow resonators - Google Patents

Abstract

577,530. Velocity modulated discharge tubes. PEARCE, A. F., BARFORD, N. C., and MAYO, B. J. Dec. 16, 1941, Nos. 16230/41 and 681/43. [Classes 39 (i) and 40 (v)] In a velocity-modulated electron discharge device working as an oscillation generator, wherein the electron beam is reflected back through the resonator 6 by a reflecting electrode or electrode system 8, the shape of the electrode and the operating potentials are such that at the zero equipotential surface in the reflecting system the potential gradient is small, i.e. not more than 0.6 of the gradient averaged over the distance between the centre of the resonator gap and the zero equipotential surface. Sizes of the orifices in the resonator gap and electrode 8 and other dimensions related to potentials are given. The electrode 8 may be a deep cylinder as shown in Fig. 4, a frustum of a cone, Fig. 5, or formed of a number of parts 17, 16, Fig. 6, the part 17 being at a potential between that of the resonator and the reflecting electrode 16. The beam may be of ribbon form as set out in Specification 574,512, or annular or radial as described in Specification 577,037, the reflecting electrode system being suitably designed to deal with the shape of beam. With the forms described, as the potential applied to the resonator varies, to maintain efficiency the numerical value of the potential applied to the reflector electrode should vary in the same sense. As a consequence, such an oscillation generator is particularly suitable as the local oscillator 11, Fig. 7, in a superheterodyne receiver, whose applied control potentials are obtained from discriminator 14, sensitive to frequency changes in an intermediate frequency amplifier 12.