[en] A patent is claimed for the invention of an electron gun equipped with an optical beam modulator. The system consists of a photocathode, a high-frequency light-source, and an optical modulator between the light source and the photocathode. The optical modulator is controlled by a high-frequency electromagnetic field. By means of a hyperfrequency line, the electron gun can be used in hyperfrequency oscillators and amplifiers. The system is able of producing pulsed beams for beam injection in high energy accelerators

[en] The characteristics of high power RF sources are subject to increasingly demanding requirements, and, precisely for this reason, much important progress is made in this field. These klystrons are used mainly in two fields : radars and scientific instrumentation. Particle accelerators create the needs for higher and higher peak or CW power levels, and also high efficiencies, in order to optimize the costs of installation and utilization. Plasma heating tubes benefit from progress in these areas, but an additional requirement of tolerance of high output SWR is imposed because of the plasma which is a very instable, fluctuating load

[en] Thanks to a strong collaboration and continuous technical exchanges between the physicists, the project designers and the engineers, the evolution of the RF and microwave technologies is outstanding. The industry has been able to develop the corresponding key components - such as the vacuum elector tubes - on time or more precisely in the necessary advance over the coming experimental fusion programs. (orig.)

[en] A review of recent developments in the design and fabrication of klystrons is presented. These include improving the efficiency, output power, the output circuit and window, reflected electrons - unmatched loads, and means of fabrication and testing

[en] In existing proton linacs, the choice of the RF frequency used at the beginning of the accelerator is the result of a difficult compromise between the injection energy (that is, the dimensions of the electrostatic injector), and the diameter of the accelerating structure (chosen in such a way as to allow the first quadrupole lens to be contained in the first drift tube). With few exceptions, the RF frequency used is 200 MHz. At this frequency, triodes can supply a few MW of peak power, but only with a duty cycle of a few percent or less. Klytrons would be able to improve this situation but at this frequency the problem of klystron dimensions is encountered. Recent developments of RFQ technology allow some of these difficulties to be overcome by forming a bridge between the injector (which thus can operate at a few tens of kV) and the beginning of the accelerator (which then use an RF frequency at least twice as high). Klystrons are now perfectly adapted for operation in this frequency range (350-500 MHz). Very high-performance klystrons have been developed for electron accelerators. Klystrons can cover the entire frequency range necessary for multi-GeV proton accelerators. The present-day possibilities are discussed and improvements which can be anticipated in the near future are described

No abstract available

[en] These klystrons are used mainly in two fields: radars and scientific instrumentation. Particle accelerators create the needs for higher and higher peak or CW power levels, and also high efficiencies, in order to optimize the costs of installation and utilization. Plasma heating tubes benefit from progress in these areas, but an additional requirement of tolerance of high output SWR is imposed because of the plasma which is a very instable, fluctuating load

[en] A description is given of the development of a high power gyrotron. (U.K.)

[en] Design considerations for the TH 2103, a new high-power klystron developed by Thomson-CSF for additional plasma heating in controlled fusion experiments, are presented. Measurements performed on the first prototypes are compared with the calculated values of parameters such as efficiency, thermal losses and distribution, beam characteristics, etc., demonstrating the validity of computer codes used in the CAD. These tubes are now entering production. (author)

[en] Some technological problems concerning the klystron and the gyrotron are discussed. For klystrons, the more urgent questions are the multipactor effect, the efficiency, the band width, the RF output windows and the collector. For gyrotrons, frequency limits and wall losses, RF windows, the external circuits and the polarization of the field are presented