Observation of Reversed-Shear Alfv?n Eigenmodes Excited by Energetic Ions in a Helical Plasma
- K. Toi
- F. Watanabe
- T. Tokuzawa
- K. Ida
- S. Morita
- T. Ido
- A. Shimizu
- M. Isobe
- K. Ogawa
- D. A. Spong
- Y. Todo
- T. Watari
- S. Ohdachi
- S. Sakakibara
- S. Yamamoto
- S. Inagaki
- K. Narihara
- M. Osakabe
- K. Nagaoka
- Y. Narushima
- K.Y Watanabe
- H. Funaba
- M. Goto
- K. Ikeda
- T. Ito
- O. Kaneko
- S. Kubo
- S. Murakami
- T. Minami
- J. Miyazawa
- Y. Nagayama
- M. Nishiura
- Y. Oka
- R. Sakamoto
- T. Shimozuma
- Y. Takeiri
- K. Tanaka
- K. Tsumori
- I. Yamada
- M. Yoshinuma
- K. Kawahata
- A. Komori
- Experiment Group LHD
Publication date
October 2010
DOI Publisher
American Physical Society (APS)Abstract
Reversed-shear Alfv?n eigenmodes were observed for the first time in a helical plasma having negative q0′′ (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 Alfv?n eigenmodes with energetic ion driven geodesic acoustic modes generates a multitude of frequency-sweeping modes
Add to ORKG