GB556530A - Electron discharge apparatus - Google Patents

Abstract

556,530. Discharge apparatus. STANDARD TELEPHONES & CABLES, Ltd. April 3, 1942, No. 4480. Convention date, April 4, 1941. [Classes 39 (i) and 40 (iii)] An electron discharge device of the velocitymodulation type comprises means for projecting an electron beam in a given direction through and beyond an input space, means for establishing in the input space electric and magnetic fields of constant intensity normal to the beam direction and to one another, the strengths of the fields being so adjusted relative to the length of the input space that electrons emerge therefrom in substantially the same direction, and means for generating in the input space a high frequency alternating electric field in a direction normal to the magnetic field. An electron beam from cathode 12, Fig. 1, focused by lens 14, 15, 16, passes into an input space between two plates 17 between which battery 27 maintains a steady potential. Coil 23 maintains a magnetic field perpendicular to the plane of view. The electrons describe a complete number of cycloids in the input space. If now an alternating voltage of a frequency at or near that of the cycloids is applied between plates 17, by transformer 30, the emergent beam is velocity modulated. After correction as to direction by plates 37, and as to dispersion by focusing coil 36, the now-bunched beam passes into a similar output space, wherein energy is delivered up to plates 19, before the beam is finally collected by anode 21. In a modification, the plates 17, 19 are replaced by a resonator 40, Fig. 3, split longitudinally into halves insulated at 41. The tube 44 provides a drift space between the input and output spaces 18a, 20a, which are back-coupled by a line 46. The device may be used as a repeater, Fig. 6, when the input and output spaces are formed by interrupting the central conductors of two coaxial lines 50, 56, near their terminations. Diaphragms 52 with four sectoral apertures convert the ends of the lines into resonant chambers. Anti-resonant chambers 58 prevent leakage along D.C. leads. The alternating electric field need not coincide in direction with the constant electric field, so long as it is normal to the magnetic field ; in Fig. 3 it is perpendicular to the constant field.