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Author(s):
Ya. I. Kolesnichenko, K. Yamazaki, S. Yamamoto, V.V. Lutsenko, N. Nakajima, Y. Narushima, K. Toi, Yu. V. Yakovenko
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Title:
Interplay of Energetic Ions and Alfven Modes in Helical Plasmas
Date of publication:
Aug. 2003
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Key words:
helical plasma, Alfven eigenmodes, Alfven continuum, energetic ions, growth rate
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Abstract:
Alfven eidenmodes and their destabilization by energetic ions in stellarators, mainly, in the Large Helical Device (LHD) plasmas, are considered. A general expression for the instability growth rate is derived, which generalizes that obtained in Ref. [Ya.I. Kolesnichenko et al., Phys. Plasmas 9, 517 (2002)] by taking into account the finite magnitude of the perturbed longitudinal magnetic fleld. The structures of the Alfven continuum and Allvn eigenmodes, as well as the resonances of the wave-particle interaction, are studied. A numerical simulation of the destabilization of Alfven waves with low mode numbers during neutral-beam injection in a particular LHD shot is carried out. The obtained solutions represent even and odd core-localized Toroidicity-induced Alfven Eigenmodes, the calculated frequencies and the mode numbers being in agreement with experimental data. The growth rates of the instabilities are calculated. This work was done during the stay of Ya.I. Kolesnichenko in NIFS as a Guest Professor from January 26, 2003 to April 25, 2003.
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