Global MHD modes excited by energetic ions in heliotron/torsatron plasmas

K. Toi; M. Takechi; S. Takagi; G. Matsunaga; M. Isobe; T. Kondo; M. Sasao; D. S. Darrow; K. Ohkuni; S. Ohdachi; R. Akiyama; A. Fujisawa; M. Gotoh; K. Ida; H. Idei; H. Iguchi; S. Kado; M. Kojima; S. Kubo; S. Lee; K. Matsuoka; T. Minami; S. Morita; N. Nikai; S. Nishimura; S. Okamura; M. Osakabe; A. Shimizu; Y. Shirai; C. Takahashi; K. Tanaka; T. Watari; Y. Yoshimura

doi:10.1088/0029-5515/39/11Y/336

Global MHD modes excited by energetic ions in heliotron/torsatron plasmas

K. Toi, M. Takechi, S. Takagi, G. Matsunaga, M. Isobe, T. Kondo, M. Sasao, D. S. Darrow, K. Ohkuni, S. Ohdachi, R. Akiyama, A. Fujisawa, M. Gotoh, K. Ida, H. Idei, H. Iguchi, S. Kado, M. Kojima, S. Kubo, S. LeeK. Matsuoka, T. Minami, S. Morita, N. Nikai, S. Nishimura, S. Okamura, M. Osakabe, A. Shimizu, Y. Shirai, C. Takahashi, K. Tanaka, T. Watari, Y. Yoshimura

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Abstract

Fishbone-like burst modes (FBs) and toroidal Alfven eigenmodes (TAEs) excited by energetic ions were observed for the first time in CHS heliotron/torsatron plasmas heated by co-injected neutral beams, where the rotational transform is increased by the induced beam driven current. FBs of m = 3/n = 2 (where m, n are the poloidal and toroidal mode numbers) induce a pulsed increase in the energetic ion loss flux. FBs of m = 2/n = 1 induce sawtooth oscillations in the latter half of a discharge where the plasma β becomes high. Only when the beam velocity exceeds about half of the central Alfven velocity and the net plasma current is induced to the required level are TAEs with n = 1 and n = 2 excited; these are localized in the plasma core region, where the magnetic shear is appreciably reduced by the net plasma current. So far, TAE induced energetic ion loss has not been observed.

Original language	English
Pages (from-to)	1929-1933
Number of pages	5
Journal	Nuclear Fusion
Volume	39
Issue number	Special Issu
DOIs	https://doi.org/10.1088/0029-5515/39/11Y/336
Publication status	Published - 1999
Externally published	Yes

All Science Journal Classification (ASJC) codes

Nuclear and High Energy Physics
Condensed Matter Physics

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10.1088/0029-5515/39/11Y/336

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Toi, K., Takechi, M., Takagi, S., Matsunaga, G., Isobe, M., Kondo, T., Sasao, M., Darrow, D. S., Ohkuni, K., Ohdachi, S., Akiyama, R., Fujisawa, A., Gotoh, M., Ida, K., Idei, H., Iguchi, H., Kado, S., Kojima, M., Kubo, S., ... Yoshimura, Y. (1999). Global MHD modes excited by energetic ions in heliotron/torsatron plasmas. Nuclear Fusion, 39(Special Issu), 1929-1933. https://doi.org/10.1088/0029-5515/39/11Y/336

Toi, K, Takechi, M, Takagi, S, Matsunaga, G, Isobe, M, Kondo, T, Sasao, M, Darrow, DS, Ohkuni, K, Ohdachi, S, Akiyama, R, Fujisawa, A, Gotoh, M, Ida, K, Idei, H, Iguchi, H, Kado, S, Kojima, M, Kubo, S, Lee, S, Matsuoka, K, Minami, T, Morita, S, Nikai, N, Nishimura, S, Okamura, S, Osakabe, M, Shimizu, A, Shirai, Y, Takahashi, C, Tanaka, K, Watari, T & Yoshimura, Y 1999, 'Global MHD modes excited by energetic ions in heliotron/torsatron plasmas', Nuclear Fusion, vol. 39, no. Special Issu, pp. 1929-1933. https://doi.org/10.1088/0029-5515/39/11Y/336

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title = "Global MHD modes excited by energetic ions in heliotron/torsatron plasmas",

abstract = "Fishbone-like burst modes (FBs) and toroidal Alfven eigenmodes (TAEs) excited by energetic ions were observed for the first time in CHS heliotron/torsatron plasmas heated by co-injected neutral beams, where the rotational transform is increased by the induced beam driven current. FBs of m = 3/n = 2 (where m, n are the poloidal and toroidal mode numbers) induce a pulsed increase in the energetic ion loss flux. FBs of m = 2/n = 1 induce sawtooth oscillations in the latter half of a discharge where the plasma β becomes high. Only when the beam velocity exceeds about half of the central Alfven velocity and the net plasma current is induced to the required level are TAEs with n = 1 and n = 2 excited; these are localized in the plasma core region, where the magnetic shear is appreciably reduced by the net plasma current. So far, TAE induced energetic ion loss has not been observed.",

author = "K. Toi and M. Takechi and S. Takagi and G. Matsunaga and M. Isobe and T. Kondo and M. Sasao and Darrow, {D. S.} and K. Ohkuni and S. Ohdachi and R. Akiyama and A. Fujisawa and M. Gotoh and K. Ida and H. Idei and H. Iguchi and S. Kado and M. Kojima and S. Kubo and S. Lee and K. Matsuoka and T. Minami and S. Morita and N. Nikai and S. Nishimura and S. Okamura and M. Osakabe and A. Shimizu and Y. Shirai and C. Takahashi and K. Tanaka and T. Watari and Y. Yoshimura",

year = "1999",

doi = "10.1088/0029-5515/39/11Y/336",

language = "English",

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T1 - Global MHD modes excited by energetic ions in heliotron/torsatron plasmas

AU - Toi, K.

AU - Takechi, M.

AU - Takagi, S.

AU - Matsunaga, G.

AU - Isobe, M.

AU - Kondo, T.

AU - Sasao, M.

AU - Darrow, D. S.

AU - Ohkuni, K.

AU - Ohdachi, S.

AU - Akiyama, R.

AU - Fujisawa, A.

AU - Gotoh, M.

AU - Ida, K.

AU - Idei, H.

AU - Iguchi, H.

AU - Kado, S.

AU - Kojima, M.

AU - Kubo, S.

AU - Lee, S.

AU - Matsuoka, K.

AU - Minami, T.

AU - Morita, S.

AU - Nikai, N.

AU - Nishimura, S.

AU - Okamura, S.

AU - Osakabe, M.

AU - Shimizu, A.

AU - Shirai, Y.

AU - Takahashi, C.

AU - Tanaka, K.

AU - Watari, T.

AU - Yoshimura, Y.

PY - 1999

Y1 - 1999

N2 - Fishbone-like burst modes (FBs) and toroidal Alfven eigenmodes (TAEs) excited by energetic ions were observed for the first time in CHS heliotron/torsatron plasmas heated by co-injected neutral beams, where the rotational transform is increased by the induced beam driven current. FBs of m = 3/n = 2 (where m, n are the poloidal and toroidal mode numbers) induce a pulsed increase in the energetic ion loss flux. FBs of m = 2/n = 1 induce sawtooth oscillations in the latter half of a discharge where the plasma β becomes high. Only when the beam velocity exceeds about half of the central Alfven velocity and the net plasma current is induced to the required level are TAEs with n = 1 and n = 2 excited; these are localized in the plasma core region, where the magnetic shear is appreciably reduced by the net plasma current. So far, TAE induced energetic ion loss has not been observed.

AB - Fishbone-like burst modes (FBs) and toroidal Alfven eigenmodes (TAEs) excited by energetic ions were observed for the first time in CHS heliotron/torsatron plasmas heated by co-injected neutral beams, where the rotational transform is increased by the induced beam driven current. FBs of m = 3/n = 2 (where m, n are the poloidal and toroidal mode numbers) induce a pulsed increase in the energetic ion loss flux. FBs of m = 2/n = 1 induce sawtooth oscillations in the latter half of a discharge where the plasma β becomes high. Only when the beam velocity exceeds about half of the central Alfven velocity and the net plasma current is induced to the required level are TAEs with n = 1 and n = 2 excited; these are localized in the plasma core region, where the magnetic shear is appreciably reduced by the net plasma current. So far, TAE induced energetic ion loss has not been observed.

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JO - Nuclear Fusion

JF - Nuclear Fusion

IS - Special Issu

ER -

Global MHD modes excited by energetic ions in heliotron/torsatron plasmas

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