Abstract: The present invention concerns a device for fixing the skirt of a grid made of pyrolytic graphite to the base of an electron tube, the fixation device being constituted by a ring fixed onto the base of the tube against which is maintained the skirt of the grid by means of abutments.

Abstract: In an electron tube with coaxial electrodes comprising an anode, a cathode and at least one grid, the base of each electrode being connected to the outside through a connection, there is mounted between the base of the grid and said connection a solid annular piece having a duct for the passage of a cooling fluid, said duct being connected to at least one fluid inlet tube and one fluid outlet tube.

Abstract: An electron tube with a cathode cooling device comprising an anode, a cathode and at least one grid in which the cathode is connected to an output connection through at least one skirt. Inside said tube, at the level of the connection between said skirt and said output connection, a tubular element is provided comprising a spiral shaped part which is extended by at least one inlet tube and one outlet tube emerging on the outside, said tubular element having a cooling fluid flowing therethrough.

Abstract: A directly-heated cathode for power electron tubes such as triodes, tetrodes or pentodes comprises a cylindrical sleeve constituted by a lattice of crossed wires forming the emissive portion of the cathode and by two conductive plates attached respectively to each end of the sleeve. In order to permit free deformation of the cathode, a flexible metallic bellows element is fixed between one of the plates and the corresponding end of the cylindrical sleeve.

Abstract: The method according to the invention comprises winding a metal wire substantially helically both round a fitting constituted by a flexible strip and around two rods arranged parallel to the fitting axis and on either side of the fitting. The rods are eliminated when the metal wire is wound. The fitting comprises means limiting the displacement of the wire in accordance with the fitting axis, which coincides with the axis of the helix according to which the wire is found. These means are constituted by two rows of slots made in the lengthwise direction on two opposite edges of the strip constituting the fitting.

Abstract: In an electron tube having coaxial cylindrical electrodes and at least one cylindrical grid of pyrolytic graphite, the grid is joined to the upper portion of a central conducting mast by means of a bell which is also of pyrolytic graphite and fixed on the mast. Slits are cut at uniform intervals around the periphery of the bell in order to form resilient strips which serve to establish an electrical contact between the grid and the conducting mast.

Abstract: A flat grid of pyrolytic graphite is obtained by cutting a disc from a cylindrical blank followed by deformation under pressure and by means of a partial vacuum. The grid is then machined and stretched within a stressing frame which also serves to mount the grid within the electron tube.

Abstract: A thin-walled grid of pyrolytic graphite for a high-power electron tube such as a triode or tetrode has a lower end in the form of a bell-shaped sleeve provided with uniformly spaced longitudinal slots which stop short of the edge of the sleeve. The solid edge portion thus formed beneath each slot serves to fit the sleeve over a metal ring of the electron tube base. The grid sleeve is clamped against the metal ring by means of screws engaged in internally-threaded bores of the ring. The edge portions of the graphite sleeve are thus fractured so as to form longitudinal strips which compensate for differences in expansion between the graphite and the metal while ensuring good electrical contact.