GB837292A - Electron tube apparatus - Google Patents

Abstract

837,292. Velocity-modulated tubes. VARIAN ASSOCIATES. Aug. 3, 1956, No. 24061/56. Class 39(1). A discharge device, e.g. a reflex klystron, comprises an evacuated portion including an internal cavity resonator positioned for electromagnetic interaction with the electron beam and having an iris opening in the wall thereof, an unevacuated external cavity resonator vacuum-sealed to the device so as to be coupled through the iris opening to the first cavity resonator, and a member of wave-energy permeable material vacuum-sealing the first resonator from the second, this member being vacuum-sealed within the second resonator. The central body portion 1 of the reflex klystron comprises a rectangular block of steel having a large longitudinal bore 2 located slightly offcentre therein there being a curved cut or iris opening 3 on one side of the block 1 opening into the bore 2. A cylindrical re-entrant tube 5 is secured by means of a header 4 within the bore, an accelerating grid 6 and a resonator grid 7 being secured over the ends of the tube 5. A reflector assembly, including a reflector bulb 8 a second resonator grid 22 secured over its open end and a reflector button 15, is secured in one end of the bore 2 and in the other end is secured a cathode assembly including an indirectly heated cathode button 29 and a cylindrical focusing electrode and heat shield 28. A multi-stepped waveguide adapter 32 having an opening 34 larger than the iris opening 3 is mounted over the opening 3. A window of wave-energy permeable material such as mica is secured within the adapter 32 over the opening 34. Threaded through one wall of the adapter 32 is a window-loading screw 35. Secured to the outer end of adapter 32 is a rectangular waveguide section 37 having a mounting flange 38 in which is an output opening 38<SP>1</SP>. Secured within a bore in the upper surface of the section 37 is a split-rod tuner assembly, which is described and claimed in Specification 810,237. In a modification, Fig. 4 (not shown), the body of the klystron comprises a machined block of metal in one end of which the cathode assembly is secured and to the other end of which is brazed a solid metal cylinder housing the reflector assembly. Metallic annular headers are brazed within the block to mount the second resonator grid and re-entrant tube. In place of a multi-stepped waveguide adapter a solid block of metal is brazed within a rectangular section of waveguide to reduce waveguide volume at the iris window. Specifications 790,142, 837,293 and 837,294 also are referred to.