Objectif Gyrotrons produce CW and long-pulsed mm-wave radiation with unmatched power level and, therefore, are extensively applied for plasma fusion electron cyclotron resonance heating and current drive and for materials processing. Recent improvements in gyrotron design and fabrication technologies resulted in substantial progress in the output parameters of such devices. But up to now the efficiency of these tubes typically does not exceed 40-50%, and needs to be further enhanced. The usual obstacle phenomenon for such an enhancement is a low-frequency oscillatory process (LFO) developing in the helical electron beam (HEB). In gyrotrons HEBs are used as an active medium for DC to RF energy conversion. These LFOs are caused by electron trapping between the cathode and the gyrotron resonator, were the beam is compressed by the increasing magnetic field. The contribution of LFOs to the electron energy spread provokes a reduction of the gyrotron efficiency. Another possible cause for energy spread growth and efficiency decrease can be associated with a spatial non-uniformity of the HEB, originating, for instance, from non-uniformity of cathode emission. These two factors are usually considered to have the strongest negative influence on the beam quality. Even presently, the available quantitative data on their effect are absolutely insufficient. So, acceptable methods for suppression or neutralization of such features have to be developed.The present project includes studies of mechanisms of the influence of non-uniformity and LOFs of an annular electron beam on its quality and investigation of the ways of gyrotron efficiency enhancement through suppression of parasitic oscillations and reduction of the negative effect of beam non-uniformity. These principle objectives are planned to be achieved as the result of theoretical and experimental investigations of the influence of these two factors on electron beam energy spread and on overall gyrotron efficiency. Methods for the reduction of the negative effects from these parasitic phenomena will be developed. This work is expected to yield new scientifically valuable data on HEB space charge behavior and information on the ways for efficiency enhancement in high-power gyrotrons. Participating in the work on the project will be recognized scientists from Forschungszentrum Karlsruhe (Germany), Helsinki University of Technology (Finland), Institute of Applied Physics Nizhny Novgorod (Russia), St. Petersburg State Polytechnical University (Russia) and Ioffe Physico-Technical Institute (Russia). Large and supplementary scientific experiences of the participating teams give ground to expect the successful fulfilment of the planned complex investigations. Programme(s) IC-INTAS - International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993- Thème(s) OPEN - OPEN Call Appel à propositions Data not available Régime de financement Data not available Coordinateur Helmholtz-Gemeinschaft Forschungszentrum Karlsruhe Contribution de l’UE Aucune donnée Adresse Hermann-von-Helmholtz-Platz 1 76021 Karlsruhe Allemagne Voir sur la carte Liens Site web Opens in new window Coût total Aucune donnée Participants (4) Trier par ordre alphabétique Trier par contribution de l’UE Tout développer Tout réduire Helsinki University of Technology Finlande Contribution de l’UE Aucune donnée Adresse Rakentajanaukio 4 FIN-02150 Espoo Voir sur la carte Coût total Aucune donnée Russian Academy of Sciences A.F. Ioffe Physico-Technical Institute RAS Russie Contribution de l’UE Aucune donnée Adresse Polytechnicheskaja 26 194021 Saint Petersburg Voir sur la carte Coût total Aucune donnée Russian Academy of Sciences Institute of Applied Physics RAS Russie Contribution de l’UE Aucune donnée Adresse Ulyanova 46 603950 Nizhny Novgorod Voir sur la carte Coût total Aucune donnée St. Petersburg State Polytechnical University Russie Contribution de l’UE Aucune donnée Adresse Polytechnicheskaja 29 195251 Saint Petersburg Voir sur la carte Coût total Aucune donnée