GB583214A - Improvements in or relating to electron discharge devices of the velocity modulationtype - Google Patents

Abstract

583,214. Velocity - modulated tubes. STANDARD TELEPHONES & CABLES, Ltd., FREMLIN, J. H., and STRACHEY, C. Dec. 12, 1941, No. 16092. [Class 39 (i)]. In an electron discharge device of the kind in which a beam of electrons is velocitymodulated by a high-frequency field and is then reflected back into the same field for energy abstraction, the potential in the reflecting field is made to vary parabolically down to a potential at or near cathode potential. In such a field, the retarded electrons all have the same transit time between successive passages . of the high-frequency field, and if this time is arranged to be an odd number of half-cycles, energy will be given up on both passages. In the simplest case, the potential is constant after the point at or near cathode potential is reached, and the accelerated electrons will not be reflected. To prevent the.loss of.the energy gained by these electrons and to avoid secondary emission when they strike the reflector, the potential curve after the point at or near cathode potential is preferably made to follow an isochronous curve so that all the accelerated electrons are reflected with the same transit time, which is greater by an odd number of half-cycles than the transit time of the retarded electrons. The accelerated electrons thus return their energy to the high-frequency field. In practical embodiment, the reflector 3, Fig. 6, is at high negative potential and interposed between it and the rhumbatron 5 is an apertured plate 8 at cathode potential. The rhumbatron and the plate are provided with conical flanges 7, 9 which give the desired distribution of potential as shown in Fig. 5, in which potential relative to the cathode is plotted against distance from the gap of the rhumbatron. Specification 583,213 is referred to.