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Experimental studies of Alfvén eigenmodes (AE) and other fluctuations with similar frequencies are essential for understanding and controlling fast ion transport and losses in magnetic fusion reactors. To this end, an 8 channel, 4 second, 1 MHz fast magnetics diagnostic has been calibrated at JET and used in the 1997 D-D and D-T campaigns. The diagnostic can measure fluctuations from up to 500 kHz with edge amplitudes deltaB/B>E-8 and toroidal mode numbers from -20 to +20. AEs driven by interrupted current rise heating (ICRH) tail ions with power threshold of about 5 MW in various heating schemes are discussed. Evidence is presented for AEs driven by alpha particles. Fluctuations are also driven at the different frequency between two independent ICRH modules. These beatwaves and fast-particle excitation may drive large AEs, modifying fast ion transport, and providing a basis for alpha channelling.

Additional information

Authors: HEETER R F, Princeton University Plasma Physics Laboratory (US);FASOLI A, École Polytechnique Fédérale de Lausanne, Centre de Recherches en Physique des Plasmas (CH);BORBA D N, Associacao EURATOM/IST Lisbon (PT);START D, JET Joint Undertaking, Abingdon, Oxon (GB);ALI-ARSHAD S, JET Joint Undertaking, Abingdon, Oxon (GB);SHARAPOV S, JET Joint Undertaking, Abingdon, Oxon (GB)
Bibliographic Reference: Article: Bulletin of the American Physical Society, Vol. 42 (1997) No. 10, p.1860
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