Status of the New Multi-Frequency ECRH System for ASDEX Upgrade


D. Wagner, F. Leuterer, A. Manini, F. Monaco, M. Münich, H. Schütz,

J. Stober, H. Zohm, T. Franke

Max-Plank-Institut für Plasmaphysik, EURATOM-IPP, Boltzmannstr.2, D-85748 Garching, Germany

M. Thumm1, R. Heidinger2, I. Danilov2, G. Gantenbein1, J. Flamm1

Forschungszentrum Karlsruhe, EURATOM-FZK

1Institut für Hochleistungsimpuls- und Mikrowellentechnik,

2Institut für Materialforschung,

PO Box 3640, D-76021 Karlsruhe, Germany

W. Kasparek

Institut  für Plasmaforschung, Universität Stuttgart, Pfaffenwaldring 31,

D-70569 Stuttgart, Germany

A.G. Litvak3, L.G. Popov4, V.O. Nichiporenko4, V.E. Myasnikov4, G.G. Denisov3,

E.M. Tai4, E.A. Solyanova4, S.A. Malygin4

3 Institute of Applied Physics, RAS, 46 Ulyanov St., Nizhny Novgorod, 603950, Russia

4 GYCOM Ltd, 46 Ulyanov St., Nizhny Novgorod, 603155, Russia




A two-frequency GYCOM gyrotron, Odissey-2, has been installed and put into operation in the new multi-frequency ECRH system at the ASDEX Upgrade tokamak experiment. It works at 105GHz and 140GHz with output power 640kW and 880kW respectively at a pulse length of 10s. Meanwhile, the first two-frequency gyrotron Odissey-1, which was damaged last year,  is back at GYCOM for repair. It will be equipped with a broadband Brewster output window and therefore become a multi-frequency gyrotron. A further extension of the system with 2 more gyrotrons is underway. Depending on the success of Odissey-1, these gyrotrons will also be step-tunable and operate at two additional intermediate frequencies between 105 and 140GHz. Construction and cold test of a first broadband double-disc torus window are completed. The transmission to the torus is in normal air, through corrugated aluminum HE11 waveguides with I.D.=87mm over a total length of about 70m. Calorimetric measurements gave a total transmission loss of only 12% at 105GHz and 10% at 140GHz. The variable frequency will significantly extend the operating range of the ECRH system with respect to the applied toroidal magnetic field. A feedback system for the mirror control is under development, to keep the ECRH deposition on the resonant q-surface while the plasma is evolving. This is required for applications such as the suppression of neoclassical tearing modes.