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Global Alfvén eigenmodes are studied using fluid and kinetic plasma models to determine how the finite Larmor excursions of the bulk species and the resonant Landau interactions modify the spectrum in the toroidicity Alfvén eigenmode (TAE) range of frequencies. A new kinetic Alfvén mode conversion mechanism is described taking place away from the resonances through toroidal coupling, when the spatial scales of the fast and the kinetic Alfvén waves become comparable. If the Landau damping of the mode converted wave is sufficiently small, groups of kinetic Alfvén eigenmodes (KAE) appear inside and above the fluid gap; those induced in the neighbourhood of a global fluid mode have a broad radial extension that could lead to substantial alpha-particle losses. Using an experimental equilibrium, the theoretical Alfvén spectrum is directly compared with saddle-coil antenna measurements from the Joint European Undertaking (JET) tokamak, showing that the multiple peaks observed on the response are KAE induced in the neighbourhood of an elongation induced Alfvén eigenmode.

Additional information

Authors: JAUN A ET AL, Royal Institute of Technology, Alfvén Laboratory, Stockholm (SE);APPERT K ET AL, Centre de Recherches en Physique des Plasmas, Association EURATOM � Confédération Suisse, Ecole Polytechnique Fédérale de Lausanne (CH);FASOLI A, JET Joint Undertaking, Abingdon, Oxon (GB)
Bibliographic Reference: Article: 16th IAEA Fusion Energy Conference, Montreal (CA), October 7-11, 1996
Record Number: 199811282 / Last updated on: 1998-10-27
Original language: en
Available languages: en