Alfvén eigenmodes driven by Alfvénic beam ions in JT-60U

K. Shinohara; Y. Kusama; M. Takechi; A. Morioka; M. Ishikawa; N. Oyama; K. Tobita; T. Ozeki; S. Takeji; S. Moriyama; T. Fujita; T. Oikawa; T. Suzuki; T. Nishitani; T. Kondoh; S. Lee; M. Kuriyama; G. J. Kramer; N. N. Gorelenkov; R. Nazikian; C. Z. Cheng; G. Y. Fu; A. Fukuyama

doi:10.1088/0029-5515/41/5/313

Alfvén eigenmodes driven by Alfvénic beam ions in JT-60U

K. Shinohara, Y. Kusama, M. Takechi, A. Morioka, M. Ishikawa, N. Oyama, K. Tobita, T. Ozeki, S. Takeji, S. Moriyama, T. Fujita, T. Oikawa, T. Suzuki, T. Nishitani, T. Kondoh, S. Lee, M. Kuriyama, G. J. Kramer, N. N. Gorelenkov, R. NazikianC. Z. Cheng, G. Y. Fu, A. Fukuyama

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Abstract

Instabilities with frequency chirping in the frequency range of Alfvén eigenmodes have been found in the domain 0.1% < 〈β _h〉 < and v _b||/v _A ∼ 1 with high energy neutral beam injection in JT-60U. One instability with a frequency inside the Alfvén continuum spectrum appears and its frequency increases slowly to the toroidicity induced Alfvén eigenmode (TAE) gap on the timescale of an equilibrium change (≈200 ms). Other instabilities appear with a frequency inside the TAE gap and their frequencies change very quickly by 10-20 kHz in 1-5 ms. During the period when these fast frequency sweeping (fast FS) modes occur, abrupt large amplitude events (ALEs) often appear with a drop of neutron emission rate and an increase in fast neutral particle fluxes. The loss of energetic ions increases with a peak fluctuation amplitude of B̃ _θ/B _θ. An energy dependence of the loss ions is observed and suggests a resonant interaction between energetic ions and the mode.

Original language	English
Pages (from-to)	603-612
Number of pages	10
Journal	Nuclear Fusion
Volume	41
Issue number	5
DOIs	https://doi.org/10.1088/0029-5515/41/5/313
Publication status	Published - 2001 May
Externally published	Yes

ASJC Scopus subject areas

Nuclear and High Energy Physics
Condensed Matter Physics

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Shinohara, K., Kusama, Y., Takechi, M., Morioka, A., Ishikawa, M., Oyama, N., Tobita, K., Ozeki, T., Takeji, S., Moriyama, S., Fujita, T., Oikawa, T., Suzuki, T., Nishitani, T., Kondoh, T., Lee, S., Kuriyama, M., Kramer, G. J., Gorelenkov, N. N., ... Fukuyama, A. (2001). Alfvén eigenmodes driven by Alfvénic beam ions in JT-60U. Nuclear Fusion, 41(5), 603-612. https://doi.org/10.1088/0029-5515/41/5/313

Shinohara, K, Kusama, Y, Takechi, M, Morioka, A, Ishikawa, M, Oyama, N, Tobita, K, Ozeki, T, Takeji, S, Moriyama, S, Fujita, T, Oikawa, T, Suzuki, T, Nishitani, T, Kondoh, T, Lee, S, Kuriyama, M, Kramer, GJ, Gorelenkov, NN, Nazikian, R, Cheng, CZ, Fu, GY & Fukuyama, A 2001, 'Alfvén eigenmodes driven by Alfvénic beam ions in JT-60U', Nuclear Fusion, vol. 41, no. 5, pp. 603-612. https://doi.org/10.1088/0029-5515/41/5/313

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title = "Alfv{\'e}n eigenmodes driven by Alfv{\'e}nic beam ions in JT-60U",

abstract = "Instabilities with frequency chirping in the frequency range of Alfv{\'e}n eigenmodes have been found in the domain 0.1% < 〈β h〉 < and v b||/v A ∼ 1 with high energy neutral beam injection in JT-60U. One instability with a frequency inside the Alfv{\'e}n continuum spectrum appears and its frequency increases slowly to the toroidicity induced Alfv{\'e}n eigenmode (TAE) gap on the timescale of an equilibrium change (≈200 ms). Other instabilities appear with a frequency inside the TAE gap and their frequencies change very quickly by 10-20 kHz in 1-5 ms. During the period when these fast frequency sweeping (fast FS) modes occur, abrupt large amplitude events (ALEs) often appear with a drop of neutron emission rate and an increase in fast neutral particle fluxes. The loss of energetic ions increases with a peak fluctuation amplitude of {\~B} θ/B θ. An energy dependence of the loss ions is observed and suggests a resonant interaction between energetic ions and the mode.",

author = "K. Shinohara and Y. Kusama and M. Takechi and A. Morioka and M. Ishikawa and N. Oyama and K. Tobita and T. Ozeki and S. Takeji and S. Moriyama and T. Fujita and T. Oikawa and T. Suzuki and T. Nishitani and T. Kondoh and S. Lee and M. Kuriyama and Kramer, {G. J.} and Gorelenkov, {N. N.} and R. Nazikian and Cheng, {C. Z.} and Fu, {G. Y.} and A. Fukuyama",

year = "2001",

month = may,

doi = "10.1088/0029-5515/41/5/313",

language = "English",

volume = "41",

pages = "603--612",

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T1 - Alfvén eigenmodes driven by Alfvénic beam ions in JT-60U

AU - Shinohara, K.

AU - Kusama, Y.

AU - Takechi, M.

AU - Morioka, A.

AU - Ishikawa, M.

AU - Oyama, N.

AU - Tobita, K.

AU - Ozeki, T.

AU - Takeji, S.

AU - Moriyama, S.

AU - Fujita, T.

AU - Oikawa, T.

AU - Suzuki, T.

AU - Nishitani, T.

AU - Kondoh, T.

AU - Lee, S.

AU - Kuriyama, M.

AU - Kramer, G. J.

AU - Gorelenkov, N. N.

AU - Nazikian, R.

AU - Cheng, C. Z.

AU - Fu, G. Y.

AU - Fukuyama, A.

PY - 2001/5

Y1 - 2001/5

N2 - Instabilities with frequency chirping in the frequency range of Alfvén eigenmodes have been found in the domain 0.1% < 〈β h〉 < and v b||/v A ∼ 1 with high energy neutral beam injection in JT-60U. One instability with a frequency inside the Alfvén continuum spectrum appears and its frequency increases slowly to the toroidicity induced Alfvén eigenmode (TAE) gap on the timescale of an equilibrium change (≈200 ms). Other instabilities appear with a frequency inside the TAE gap and their frequencies change very quickly by 10-20 kHz in 1-5 ms. During the period when these fast frequency sweeping (fast FS) modes occur, abrupt large amplitude events (ALEs) often appear with a drop of neutron emission rate and an increase in fast neutral particle fluxes. The loss of energetic ions increases with a peak fluctuation amplitude of B̃ θ/B θ. An energy dependence of the loss ions is observed and suggests a resonant interaction between energetic ions and the mode.

AB - Instabilities with frequency chirping in the frequency range of Alfvén eigenmodes have been found in the domain 0.1% < 〈β h〉 < and v b||/v A ∼ 1 with high energy neutral beam injection in JT-60U. One instability with a frequency inside the Alfvén continuum spectrum appears and its frequency increases slowly to the toroidicity induced Alfvén eigenmode (TAE) gap on the timescale of an equilibrium change (≈200 ms). Other instabilities appear with a frequency inside the TAE gap and their frequencies change very quickly by 10-20 kHz in 1-5 ms. During the period when these fast frequency sweeping (fast FS) modes occur, abrupt large amplitude events (ALEs) often appear with a drop of neutron emission rate and an increase in fast neutral particle fluxes. The loss of energetic ions increases with a peak fluctuation amplitude of B̃ θ/B θ. An energy dependence of the loss ions is observed and suggests a resonant interaction between energetic ions and the mode.

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JO - Nuclear Fusion

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Alfvén eigenmodes driven by Alfvénic beam ions in JT-60U

Abstract

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