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Return To: Session EXP3 - MHD Stability & Alternate Confinement
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S. Bernabei , M. G. Bell , R. Budny , D. Darrow ,
E. D. Fredrickson , J. C. Hosea , R. Majeski ,
E. Mazzucato , N. Gorelenkov 1, C. K. Phillips ,
J. H. Rogers 2, G. Schilling , J. R. Wilson ,
R. White , F. Zonca 3, S. Zweben
Princeton Plasma Physics Laboratory, P.O. box 451,
Princeton N.J. 08543
1 TRINITI, Troitsk, Moscow, Russia 142 092
2 Intevac Inc., 3550 Basset St., Santa Clara, Ca. 95054
3 Associazione EURATOM-ENEA, CRE 00044 Frascati, Italy
Abstract
High power ICRF minority heating produces an energetic tail in the
distribution function of the resonant ions. When the energy in this tail
exceeds a certain threshold, various kinds of Alfvénic instabilities can be
excited. In TFTR , it is found that modes whose frequencies decrease vs.
time
cause fast ion losses and in turn a reduced Rf heating efficiency, unlike the
usual global TAE. The frequency decrease of the modes is found to correspond
to a radial movement of t he mode itself: modelling shows that this feature
causes an avalanche of fast ion losses due to a diffusion process. The
frequency-decreasing modes play a fundamental role in the stabilization of the
sawtooth and in its subsequent crash.
IAEA 1999