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Abstract

The modelling of Alfvénic instabilities is discussed from the point of view of mode-conversion, showing how the development of the theory affects the predictions as the limitations of the models are gradually relaxed. Conventional tokamak plasmas are relatively well understood and are used for the case of a kinetic Alfvén eigenmode (AE) to assess the resonant wave-particle interactions along the magnetic field. The large safety factor in the core of deeply reversed shear plasmas and the low magnetic field of spherical tokamaks, however, bring the AEs down into the drift-frequency range; modifications of the spectrum through toroidal mode-conversion then creates a new class of drift-kinetic AEs that could affect the fast particle confinement. Experiments have been carried out to verify these predictions in JET. They confirm the presence of weakly damped modes, which do not follow the usual AEs scaling.

Paper given at 28th EPS Conference on Controlled Fusion and Plasma, held at Funchal, Madeira (PT) from 18 to 22 June 2001.

Additional information

Authors: JAUN A, Alfvén Laboratory, EURATOM-NFR Association, Stockholm (SE);FASIOLI A, Plasma Science and Fusion Center, MIT, Cambridge (US);TESTA D, Plasma Science and Fusion Center, MIT, Cambridge (US);VACLAVIK J, CRPP, Association EURATOM-Confédération Suisse, EPFL, Lausanne (CH);VILLARD L, CRPP, Association EURATOM-Confédération Suisse, EPFL, Lausanne (CH)
Bibliographic Reference: An article published in: Plasma Physics and Controlled Fusion, 43 (December 2001) 207-216
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