Abstract: An electron gun comprises a cathode for generating at least one electron beam along a beam path and a plurality of electrodes spaced along the beam path from the cathode. The electrode adjacent to the cathode comprises an electrically conductive base member of a first material having an aperture extending therethrough. The base member has two opposing surfaces that have overlying layers of a second electrically conductive material disposed thereon. The overlying layers overhang the aperture in the base member. At least one of the overlying layers has a plurality of apertures therethrough.

Abstract: A television camera tube having a diode electron gun comprising a cathode and an anode having a central aperture. The part of the anode surrounding the central aperture is situated closer to the cathode than the remainder of the anode and has an area which is smaller than 75% of the cathode's emissive surface. This configuration minimizes anode current and avoids wasted power while retaining desirable electron beam characteristics.

Abstract: The electrode is circular in configuration, with a central opening, so that it has inner and outer rims. The electrode structure comprises a plurality of spiral-shaped vanes of conducting material which are separated by relatively thin slit-like openings. The spiral vanes begin at an inner boundary which is close to the inner rim of the electrode and rotate approximately one-half turn to the outer rim of the electrode. A portion of the electron beam, which is typically produced from a cathode energized by a high voltage source, strikes the electrode near the central opening, and travels along the vanes of the electrode to ground, thereby establishing a plurality of spiral current paths in the electrode. These spiral currents create a magnetic field about the center of the anode in the region of the electron beam, focusing the remainder of electron beam through the opening in the electrode.

Abstract: Dimensional stability of an electron discharge heating device having electrodes for focussing the discharge current is improved by providing one or more heat pipes for transferring heat from an electrode to cooling fins outside the vacuum chamber. In one embodiment, a second electrode is water-cooled. The improved cooling not only permits of use of a structure which takes a short time to reach thermally stable conditions due to the small heat capacity of the solid material but also permits of different parts of the gun assembly being operated at different temperatures.

Abstract: An electron gun for a camera tube includes an anode and a cathode. The cathode is assembled in a cathode support which can very readily be adjusted relative to the anode in the nonconnected condition. In particular, the cathode support and the anode are movable radially with respect to each other and with respect to an axis. An emissive cathode surface and a part of the anode extending perpendicular to the axis remain accurately parallel to each other during the radial movement. As a result of this it is possible to cause the central path of the generated electron beam and the gun axis to coincide so that extra correction coils for aligning the electron beam may be omitted.

Abstract: The invention relates to metal oxide activated porous tungsten cathodes and methods of their manufacture. A cathode 1 of porous tungsten activated by metal oxides is mounted on a housing 2 which has a heating filament 3. On the outer face of the cathode there is a pattern or grid of pure tungsten (preferably formed by a chemical vapor deposition of WCl.sub.6 or WF.sub.6) of crystalline material the outer face of which has an orientation in the (100) or (110) plane and is parallel to the surface of the cathode. The invention will find particular use in the cathode guns of high frequency tubes such as traveling wave tubes and klystrons.

Abstract: For a grid-controlled electron source to operate at extremely high frequencies, as in planar triodes, the control grid must be situated very close to the emissive cathode. Mechanical and thermal distortions have put minimum limits on grid spacings and hence on the maximum operating frequency of grid-controlled tubes. To overcome these limits the grid structure is formed as a network of web members which are part of a laminated sheet having metal layers bonded to opposite surfaces of an insulating layer. One metal layer is affixed to the emissive surface of a metallic matrix cathode and the other metal layer forms the control grid.

Abstract: A crossed-field amplifier with a beam modulating grid for the electron gun has an auxiliary electrode which modifies the electrostatic field and thus the electron beam adjacent the entrance of the amplifier interaction space. Efficiency is improved and incidence of electrons striking the delay line is reduced.

Abstract: The electron gun includes a spherically concave cathode emitter with a pair of axially spaced spherically concave focus and control grids closely spaced overlaying the cathode emitter for controlling the beam current. The grids are supported from a common thermally conductive tubular grid support structure via the intermediary of first and second annular members one of which is a thermally conductive insulator. One or more of the grids are serrated about their peripheries to define a plurality of radially directed fingers bonded to the end of a respective annular grid support member. In an alternative embodiment, the end of the annular grid support member, as bonded to the serrated grid, is castellated to accommodate differences in thermal expansion between the grid and the annular grid support member.

Abstract: A method and apparatus for preventing oscillations in high-current electron guns. Spurious oscillations frequently occur as a result of interaction of the electron stream with the fields of resonant modes of the gun structure. The resonant impedances of the modes are lowered by damping with lossy dielectric or resistive materials which are suited to the high temperature and vacuum environment of electron guns. The lossy materials are located in places shielded from high electric fields applied to the gun. Lossy dielectric materials which are D.C. insulators may be used as insulating supports for gun electrodes.