Progress of the European 2 MW, 170 GHz Coaxial Cavity
Gyrotron for ITER
M. Thumm1,2, S. Alberti3, F.
Albajar4, K. Avramidis5, P. Benin6, T.
Bonicelli4, S. Cirant7,
O. Dumbrajs8, D. Fasel3, J. Flamm2, G. Gantenbein1, T. Goodman3, J.-P. Hogge3, S. Illy1, S. Jawla3, J. Jin1, S. Kern1, C. Lievin6, I. Pagonakis5, B. Piosczyk1, O. Prinz1, T. Rzesnicki1, M.Q. Tran3
1Forschungszentrum Karlsruhe, Association EURATOM-FZK,
Institut für Hochleistungsimpuls- und Mikrowellentechnik (IHM),
D-76021 Karlsruhe, Germany
2Universität Karlsruhe, Institut für Höchstfrequenztechnik und Elektronik (IHE),
D-76131 Karlsruhe, Germany
3Centre de Recherche en Physique des Plasmas (CRPP), Association EURATOM–Confedération Suisse, Ecole Polytechnique Fédérale de Lausanne,
CH-1015, Lausanne, Switzerland
4The European Joint
Undertaking for ITER (F4E), 0801 9
6Thales Electron Devices (TED), F-78141 Vélizy-Villacoublay, France
7Instituto di Fisica del Plasma Consiglio Nazionale delle Ricerche, I-20125 Milano, Italy
development of a 2 MW, 170 GHz gyrotron for ITER is taking place in
In the meantime the industrial prototype has been fabricated and is presently under test at CRPP Lausanne where a suitable test facility has been constructed. In short pulse operation (~ 1ms) stable single mode excitation of the nominal TE34,19 mode at 170 GHz has been obtained. At reduced parameters (83.5kV/72A) with a corresponding velocity ratio a @ 1, a maximum mm-wave output power of 1.4 MW has been measured. A further increase of the accelerating voltage was limited by arcing; parasitic LF oscillation around 170 MHz occur simultaneously. The origin of the LF oscillations, which begin typically at cathode voltages above ~ 77 kV, is not clear up to now. The measured mm-wave power is about 15% less than the corresponding value obtained from self-consistent simulations. The agreement between experiment and simulations is better for lower voltages. Presently a conditioning and optimization of the tube towards operation at nominal beam parameters (90kV/75A) and at pulses up to 1 s is underway. In parallel to the experimental studies on the first prototype tube, the basic investigations on the experimental 170 GHz pre-prototype tube have been continued.
The results obtained will be reported and discussed.