Role of Alfven instabilities in energetic ion transport
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08453 (United States)
- TRINITI, Troitsk, Moscow, Russia 142092 (Russian Federation)
Experiments with plasma heating by waves at the ion cyclotron resonance of a minority species have shown that the heating efficiency degrades above a certain power threshold. It is found that this threshold is due to the destabilization of shear Alfven waves, which causes loss of fast ions. There are two distinct regimes characterized by low q{sub a} and high q{sub a}. In the first case, the fast ion distribution created by ICRF, lies entirely inside r{sub q=1}, away from the location of global TAE. This situation leads to the formation of a very strong fast ion population which stabilizes the sawteeth, but also excites Energetic Particle Modes (EPM), which transport fast ions outside r{sub q=1} causing the giant crash. At higher q{sub a}, the widening of the Alfven gap due to the steeper q profile, brings the global TAE ''in contact'' with the fast ion distribution. This results in an immediate and continuous depletion of fast ions from the core, which prevents the formation of the monster sawtooth and the excitation of EPM. (c) 1999 American Institute of Physics.
- OSTI ID:
- 20216683
- Journal Information:
- AIP Conference Proceedings, Vol. 485, Issue 1; Other Information: PBD: 20 Sep 1999; ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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