GB548346A - Improvements in high frequency electron discharge apparatus - Google Patents

Abstract

548,346. Electron discharge apparatus. BRITISH THOMSON-HOUSTON CO., Ltd. March 3, 1941, No. 2861. Convention date, March 1, 1940. [Class 39 (i)] A stream of helically moving electrons passes first into a region in which tangentially acting cyclically varying potentials produce velocity modulation and grouping, and then into a region both axially and angularly displaced from the first region in which energy is extracted from the beam. In the form shown in Figs. 2 and 3 a beam A from the electron gun 18, 19, 20 is deflected both circumferentially and axially by deflecting plates 22, 23 and passes into a hollow metal shell 11 in which the helical motion is maintained by an axial magnetic field. The beam first passes near gaps 37, 38 formed between an aperture in the shell 11 and an inset plate 34 to which modulating potentials are applied. The electron transit time between gaps 37 and 38 is an odd number of half-cycles of the modulating frequency so that the gaps produce a cumulative velocity modulation of the beam, resulting in a cyclic variation of the radius of the electron orbit. It is shown that this produces a grouping of electrons in regions displaced 90 degrees from electrode 38, and a similar electrode 35 placed in such a region extracts useful energy from the beam. As shown, the beam may pass electrodes 34, 35 several times with a cumulative effect owing to the maintenance of the orbital period constant at an integral number of cycles by the magnetic field. Separate collector electrodes 15, 16 are provided. The envelope may be surrounded by a metal shield to which are bolted the outer conductors of two transmission lines, the inner conductors of which pass to the plates 34, 35. In the form shown in Fig. 9 diametrically opposite input and output electrodes 127, 128, 129, 130 are joined by U-shaped conductors 132, 133. In the form shown in Fig. 8, electrons from annular cathode 68 are concentrated by annular electrodes 69, 70 and deflected by plates 72, 73 into a cylindical sheet of electrons moving helically in an axial magnetic field. The sheet enters a re-entrant portion of the envelope and passes between concentric shells 75, 76 in which are inset modulating electrodes 80, 81 which are electrically connected and induce grouping in the electrons in the same manner as in Fig. 3. The shells 75, 76 are joined at the end by the collecting electrode 90, in which is inserted the output electrode 86. Specifications 518,015 and 542,182 are referred to.