Patent GB-557041-A (GB)
Title: Electron discharge device
IPC: H01J25/34
Filed: 1942-03-28
Abstract: 557,041. Phase changing. STANDARD TELEPHONES & CABLES, Ltd. March 28, 1942, No. 4184. Convention date, March 28, 1941. [Class 38 (ii)] [Also in Group XL] An ultra high frequency wave generator comprises an electron gun with cathode 1, Fig. 1, apertured electrode 5 and accelerating electrodes 6, 7 to form a beam which is rotated about the tube axis by plates 8, 9; an electrode 15 at a potential negative to the cathode and a pair of short cylindrical accelerating electrodes 16 cause deflection of the beam, whose rotation about the axis sustains standing waves in an enclosing tube, which may be outside the envelope 19 or within it, the electrode 16 in the form shown in Fig. 4 forming part of the tube 21. A collector electrode 18 just positive to the cathode is outside the electrodes 16, the beam being focused to pass between the electrodes 16. The disc electrode 15 may be replaced by a cylinder 20, Fig. 2, over the end of the electrode 7 and positive to the cathode. The deflecting potentials applied to the electrodes 8, 9 may be obtained by connecting one of each pair to the electrode 7 and thence to the outer conductor of a coaxial line 11 and the others of each pair to taps 12, 13 at desired phase quadrature on the inner conductor which is connected to a source 10 ; the end of the line 11 is connected to a surge impedance 14. Alternatively the two phase deflection supply may be obtained from probes 38, Fig. 6, projecting into wave guide 31, such an arrangement allows the device to work as a self oscillation generator. In a modification, rotation of the beam is obtained by passing it through a resonator 80, Fig. 11, into which project two probes 83 at 90 degrees; out of phase currents are supplied to these probes which produce electro static fields causing deflection of the beam. The size of the tube 21 is correlated with the time of rotation of the beam around the tube axis so as to be resonant and produce circularly polarized waves of the HI type; one end of the tube may have a reflecting wall 23, Fig. 4, the other wall 24 having a perforation, the load 22 being connected to the guide 25. Output may be taken by a probe in the tube 21, or the bidirectional radiation from the electron tube 19 may be collected in separate waves guides 46, Fig. 7, and combined to feed a common load 47. In a modification phase polarized waves are produced by deflecting the beam by means of a single pair of plates 8, Fig. 8, instead of rotating the beam; two sets of accelerating electrodes 50, 51 and two collector anodes 54, 55 are used. Deflection may be obtained by a resonator as described with reference to Fig. 11 but using only one probe. To modulate the wave a control guide 57, Fig. 1, is used in part of the cathode 1. To amplify, a modulated wave is applied to the deflecting plates 8, 9, Fig. 1, the beam not being focused on to the gap between the electrodes 16 ; as a consequence when undeflected the electrons spread over a disc like area. When deflected by the electrodes 15, 16 and in response to the deflecting potentials the point of entry of the electron beam into this disc varies giving a modulated output. With a focused beam if the deflecting potentials are great, the point of emergence of the beam from the electrode 7 may be varied an amount substantial in relation to the radius of the rotating beam about the axis i.e. the distance from the axis to the electrode 16 ; this variation will give a varying output of energy. To generate harmonics to the frequency of the control oscillations applied to the deflecting plates and therefore to the frequency of rotation of the beam, the beam is projected through slots 17, 171, Fig. 9, in a pipe 62 of a mean length equal to an integral number of the originating frequency. Energy may be withdrawn through holes 63 opened round the pipe and may be directed into a wave guide ; or probes may project into the pipe and be connected to the inner conductors of a number of coaxial lines feeding a common line. Focusing electrodes 64, 65 direct the beam into the pipe 62.