Abstract: In a noise reducer for microwave amplifiers working by pulses, a small portion of the amplifier output signal is diverted through an ancillary channel. The amplitude of the pulses of this diverted signal is greatly reduced by a limiter. The noise between the pulses can then be processed in an amplifying circuit and in a phase-shifting circuit so that, by combining the main signal in a second coupler, the noise between the pulses is eliminated. This invention can be applied to transmission amplifiers forming part of a transmission/reception set where reception takes place between the transmission pulses.

Abstract: In electron guns for electronic tubes, such as travelling wave tubes, for power modulating the electron beam, the distance between the cathode and the modulation grid increases the closer to the axis of the tube. Such a gun can be applied to travelling wave tubes operating with a zero enabling voltage and whose modulating frequency covers a very wide band.

Abstract: To ensure stability of tubes comprising a delay line of the ceiling and ring type or of the ceiling and bar type, resonating slits are disposed in the ceilings of the line.

Abstract: A delay line is provided for a travelling wave tube and comprising two parts:a first part formed from a delay line section comprising a central conductor mounted in a cylindrical sleeve by means of dielectric rods. This first part is situated on the high frequency input side of the tube and is focussed by means of a succession of permanent magnets with alternate orientations;a second part, following the first one which is formed from an entirely metal delay line section and which is focussed by means of a solenoid or a permanent magnet.

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: In a travelling wave tube in which the delay line (1) is constituted by a sequence of double resonator cavities (15) alternating with the pole pieces (3) of the focusing system, the invention provides for the purpose of limiting the interception of electrons by the line an increase in the diameter of the magnetic material collars (30, 40) terminating said pieces, as well as the wall (16) of the cavities on the side of the tube axis. This increase takes place in stages, a collar (40) having the same diameter as the collar (30) which follows it in the beam propagation direction.

Abstract: A helical microwave delay line for a travelling-wave tube, constituted by a conductor held in the envelope of the tube by insulating bars. The width of the conductor in contact with the supporting bars increases along the tube axis, particularly towards the microwave energy output.

Abstract: In a power electronic tube the outer surface of the collector is in the shape of a cylinder and has equidistant grooves formed in cross-sections and along the generatrices of this cylinder, which gives them flexibility and allows assembly with an insulating sleeve.

Abstract: The areas of the walls 1 separating two adjacent cavities that are located on the periphery of the opening 3 for allowing through the electron beam, and whose thermal resistance is greatest, are those comprised between this opening 3 and a cavity coupling opening 2. Owing to the opening 3 for allowing through the electron beam (elliptical, centered on the axis of the line 00', with the large axis of the ellipse merging with the axis of symmetry AA' of the coupling openings 2 intersecting the axis 00'), these areas are the furthest away from the axis of the line 00' along which the electron beam is propagated. The invention is applied to microwave tubes and in particular to travelling-wave tubes.

Abstract: The external outline of the transverse section of the walls externally bounding the cavities (4) is circular, but the thickness of these walls is not constant, being smaller in the zones of these walls which are not traversed by the cooling ducts (5) than in the other zones. Application to travelling-wave tubes carried in aircraft.

Abstract: A delay line for a high frequency tube that is cooled by circulating fluid.The cooling fluid circulates in a duct (FIG. 3, 10), formed in the space between two sleeves (8 and 9). The sleeves are of non-magnetic material, impervious to the cooling fluid, and have an axis parallel to the axis of the delay line. The first sleeve (8), is vacuum tight, brazed or hard soldered to dielectric supports (2) and, in cross section connects two adjacent supports in a straight line. The second sleeve (9), is cylindrical, and contains the first sleeve to which it is brazed at several points. A focusing device made of permanent magnets is mounted on the second sleeve.The invention will find use in high frequency tubes.