Energetic-ion-driven toroidal alfvén eigenmodes observed in a heliotron/torsatron plasma

M. Takechi, K. Toi, S. Takagi, G. Matsunaga, K. Ohkuni, S. Ohdachi, R. Akiyama, D. S. Darrow, A. Fujisawa, M. Gotoh, H. Idei, H. Iguchi, M. Isobe, T. Kondo, M. Kojima, S. Kubo, S. Lee, T. Minami, S. Morita, K. MatsuokaS. Nishimura, S. Okamura, M. Osakabe, M. Sasao, M. Shimizu, C. Takahashi, K. Tanaka, Y. Yoshimura

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)


Toroidal Alfvén eigenmodes (TAEs) of low toroidal mode number, n=1 and 2, are observed in neutral-beam-heated plasmas in the compact helical system heliotron/torsatron. The observed frequency is proportional to the computed TAE frequency and lies near the lower bound of the innermost TAE gap. The modes are excited only when the beam velocity exceeds about half the central Alfvén velocity and when the net plasma current induced by coinjected neutral beams is in the required range. The modes are localized in the plasma core region, between 0.2 and 0.6 of the plasma minor radius.

Original languageEnglish
Pages (from-to)312-315
Number of pages4
JournalPhysical review letters
Issue number2
Publication statusPublished - Jan 1 1999
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)


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