Abstract: The invention relates to a manufacturing process for an impregnated cathode for an electron tube and the impregnated cathode obtained in this manner. The method consists in mixing (b) a powder (Y) containing the emissive elements (generally barium and calcium aluminates) with powder (W) of at least one refractory metal (generally tungsten, if necessary mixed with a platinum ore metal), then pressing (c) this mixture into a pellet (1) which is then sintered (d) at a high temperature in hydrogen (approx. 2000.degree. C.). In the prior art of this method, a powder of at least one refractory metal was pressed and sintered and then impregnated, machined, cleaned, etc. The process according to the invention therefore saves many steps in the manufacture of an impregnated cathode with respect to the prior art.

Abstract: Disclosed are a method for the fabrication of an impregnated cathode and a cathode obtained thereby. The impregnation is obtained by applying a sol-gel method. The emissive material which impregnates the body of the cathode only partially fills the pores. This facilitates the migration of the material towards the surface and increases the lifetime of the cathode.

Abstract: This invention concerns a thermoelectronic cathode for hyperfrequency electron tubes.The cathode comprises a cylindrical molybdenum casing, the lower portion of which contains a heating filament, while the upper portion contains two superimposed porous bodies, the lower one made from impregnated material, and the upper one from non-impregnated material.

Abstract: A coupled-cavity delay line for traveling-wave tubes is provided with a cooling system which permits heat distribution along the entire length of the delay line and ensures that the outer surface of the vacuum enclosure is isothermal. The cooling system consists of a cylindrical sleeve containing heat pipes. The cylindrical sleeve is located between the external wall of the resonant cavities and the permanent magnets. The heat pipes are disposed at uniform angular intervals within the double-walled sleeve and extend lengthwise along the delay line.

Abstract: A complementary grid made from a volatile material is formed on the surface of the cathode, which is then covered with the material of the grid (parts 5 and 6). After the volatilization of the complementary grid there leaves an integrated grid (part 6) on this surface.

Abstract: A direct heating thermionic emission cathode for high frequency tubes of the diode, tetrode or pentode type. It comprises a pyrolytic graphite support and a lanthanum hexaboride-based thermoemissive material, these elements being separated by a layer which constitutes a diffusion barrier and comprises a tantalum or hafnium carbide, a metal of the platinum group or a boron compound.

Abstract: This heating element is constituted by a filament and a mixture, fritted at between 1700.degree. and 1800.degree. C., of alumina and less than 10% by weight of yttrium oxide. This mixture fills the space left free by the filament within the cylinder closed by an emissive disk forming the cathode.

Abstract: The hot cathode, according to the invention, is constituted by a fritted matrix 1 and a heating filament 4, said matrix being formed from a powder mixture 2 of tungsten and another high work function refractory metal and covered with a high work function refractory metal film 3. FIG. 3.

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: A device for collecting solar energy and conveying it to a zone to be heated. It comprises a tube in two parts, the first part (evaporator) being surrounded by a vacuum and being covered with a heat absorbing material and exposed to the solar radiation. The tube contains a fluid which vaporized in the first part and absorbs heat and condenses in the second part and gives up the previously-stored heat. The fluid in the liquid phase is returned to the first part by a capillary system.