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P17 · Excitation of Alfven Eigenmodes using the DED Coil in the TEXTOR Tokamak

T. Shoji¹, Y. Kikuchi⁵, A. Tsushima², K. Toi³, N. Noda³, G. Matsunaga⁴ K.H. Finken⁵, M. Jakubowski⁵, M. Lehnen⁵, O. Zimmermann⁵, R. Wolf⁵, A.G. Elfimov⁶

¹Department of Energy Engineering and Science, Nagoya University 464-8603, Nagoya Japan
²School of Engineering Division of Physics , Yokohama National University, Yokohama 240-8501, Japan
³National Institute of Fusion Science, Toki-shi 509-5292, Japan
⁴Japan Atomic Energy Research Institute, Ibaraki, Japan 311-0193
⁵Institute für Plasmaphysik, Forschungszentrum Jülich GmbH, EURATOM Association, Trilateral Euregio Cluster, Jülich D-52425, Germany
⁶Institute of Physics, University of San Paulo, 05508-900, San Paulo, Brazil

Abstract: Results from the first experiments to excite Alfven eigenmodes (AEs) in the TEXTOR tokamak plasma by using the dynamic ergodic diverter (DED) coils as an external antenna are presented. Notable features of AEs experiments using DED coils are exciting different modes around m/n=12/4, 6/2, 3/1 by changing the coil configuration, studying the effects of magnetic islands and edge magnetic fields ergodization on AEs when the rf current is applied for dc and AC DED operation, etc. The rf current of = 4A with scanning the frequency 100kHz-1MHz is applied on the one of the DED coils. The coil impedance versus frequency is measured for the plasma (Ip = 350 kA, Bt = 2.25 T, n_e=2-3x10¹⁹ m^-3) with AC DED (1kHz, 1.5kA) and compared with the theoretical calculation. The excited waves are detected by the Mirnov coils installed around the torus.

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