Abstract: This gun comprises a cathode K, a grid G, and an anode A between which the applied voltages are radio-frequency voltages. The cathode is disposed on the central conductor of a coaxial cavity, facing said grid terminating said cavity. Said cavity is terminated at the other end by a short-circuit and includes a coaxial branch line so as to resonate at two frequencies F.sub.1 and F.sub.2 multiple of f.sub.0, whose beating induces a radio-frequency grid-cathode voltage. Said grid terminates another coaxial cavity whose central conductor is hollow and whose end facing said grid forms the anode. said other coaxial cavity resonator is excited and resonates at a frequency F.sub.0 multiple of f.sub.0, which induces a radio-frequency anode-grid voltage.A proper selection of the frequencies F.sub.0, F.sub.1, F.sub.2 allows to obtain electrons bunches of very short duration.

Abstract: A microwave drying device for drying products in the form of grains, comprising a microwave source, at least one waveguide coupled electromagnetically to the microwave source, means for injecting into this waveguide the product to be treated, means for driving this product in the waveguide, means for causing a forced circulation of dry air in the waveguide, means for discharging the air charged with the humidity given up by the product to be treated, and means for collecting the dried product in this waveguide, wherein the waveguide is closed on itself so as to form a ring, a part of this waveguide forming a channel through which the product to be treated may pass, said channel being connected at its ends to pipes for feeding therein and removing therefrom the product, these pipes forming cut-off waveguide.

Abstract: The invention relates to a .gamma.-ray irradiation head for panoramic irradiation comprising a tungsten target revolving about an axis, and means for deflecting electrons around the same axis for producing photons in several directions either successively or simultaneously. When the beam of electrons is deflected in its entirety and when the impact zone moves on the target about the axis, the axis of the radiation lobe moves in the same way and permits irradiation according to a variable azimuth.

Abstract: An apparatus for treating waste-waters and sludges and using an irradiation beam of accelerated electrons, comprises a treatment circuit c equipped with valves, an electromagnetic regulator providing a constant flow of the fluid to be treated by the irradiation beam, systems for controlling the flow of fluid and for controlling the characteristics of the irradiation beams, a microprocessor associated with the flow control systems for controlling at least the automatic closure of a shut-off valve and the opening of a purge valve.

Abstract: An irradiation apparatus comprising a fluid-tight enclosure in which are located a linear electron accelerator, a magnetron supplying a high frequency signal, means for injecting this high frequency signal into the accelerating structure, means for supplying voltage to the magnetron and the accelerator. A magnetic deflecting system can be associated with the linear accelerator for deflecting the accelerated electrons towards a target emitting X-rays. Cooling systems are provided inside the enclosure 1, in particular for cooling the magnetron.

Abstract: An arrangement enables the frequency variation of a resonant element (an accelerating section for example) to be followed in dependence upon its temperature and the frequency of the hyperfrequency generator G feeding this resonant element Q to be controlled in dependence upon the frequency variations thereof. The arrangement comprises at least one reference cavity C associated with means for allowing the circulation of cooling fluid along the walls of said reference cavity and with heat supply for bringing it, at any instant, to the temperature of the resonant element Q, means for measuring the amplitude variation .DELTA.a of the signal corresponding to the frequency variation of said reference cavity C in terms of its temperature variation and a frequency variation system controlled by a signal proportional to the amplitude variation .DELTA.a, for modifying the operating frequency of the generator G.

Abstract: Selective transmission systems for transmitting from an H.F. generator to a load device whose electrical characteristics may vary rapidly, a pulsed main H.F. signal of given frequency, and for eliminating the spurious signal or signals accommpanying the main H.F. signal at the beginning of the pulse, when the load impedance presented to the H.F. generator is not suitable. Several embodiments are described which take account of the frequency of the spurious signals in relation to the frequency of the main signal.