Observation of Reversed-Shear Alfven Eigenmodes Excited by Energetic Ions in a Helical Plasma

Journal Article · Fri Oct 01 00:00:00 EDT 2010 · Physical Review Letters

DOI:https://doi.org/10.1103/PHYSREVLETT.105.145003· OSTI ID:21466993

Toi, K; Tokuzawa, T; Ida, K; Morita, S; Ido, T; Shimizu, A; Isobe, M; Todo, Y; Watari, T; Ohdachi, S; Sakakibara, S; Narihara, K; Osakabe, M; Nagaoka, K; Narushima, Y; Watanabe, K Y; Funaba, H; Goto, M; Ikeda, K; Kaneko, O ^[1]

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1. National Institute for Fusion Science, Toki (Japan)

Reversed-shear Alfven eigenmodes were observed for the first time in a helical plasma having negative q{sub 0}{sup ''} (the curvature of the safety factor q at the zero shear layer). The frequency is swept downward and upward sequentially via the time variation in the maximum of q. The eigenmodes calculated by ideal MHD theory are consistent with the experimental data. The frequency sweeping is mainly determined by the effects of energetic ions and the bulk pressure gradient. Coupling of reversed-shear Alfven eigenmodes with energetic ion driven geodesic acoustic modes generates a multitude of frequency-sweeping modes.

• OSTI ID: 21466993
• Journal Information: Physical Review Letters, Vol. 105, Issue 14; Other Information: DOI: 10.1103/PhysRevLett.105.145003; (c) 2010 American Institute of Physics; ISSN 0031-9007
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALFVEN WAVES
COUPLING
LAYERS
MAGNETOHYDRODYNAMICS
PLASMA
PLASMA PRESSURE
PRESSURE GRADIENTS
REVERSED SHEAR
SHEAR
TAIL IONS
VARIATIONS
CHARGED PARTICLES
FLUID MECHANICS
HYDRODYNAMICS
HYDROMAGNETIC WAVES
IONS
MECHANICS