Observation of a beam-driven low-frequency mode in Heliotron J

L. G. Zang, S. Yamamoto, D. A. Spong, K. Nagasaki, S. Ohshima, S. Kobayashi, T. Minami, X. X. Lu, N. Nishino, S. Kado, P. Adulsiriswad, H. Okada, N. Kenmochi, Inagaki Shigeru, J. X. Zhu, G. M. Weir, T. Mizuuchi, S. Konoshima, A. Ishizawa, D. L. YuZ. B. Shi, Yi Liu, L. W. Yan, J. Q. Li, Q. W. Yang, M. Xu, X. R. Duan, Yong Liu

Research output: Contribution to journalArticle

Abstract

A low-frequency electromagnetic mode (LF-mode) has been observed in a stellarator/heliotron device, Heliotron J. The LF-mode is observed only in neutral beam heated plasmas with a co-current, which increases the rotational transform. The observed LF-mode peaks at rho = 0.86-0.91, where rho = r/a is the normalized minor radius. The LF-mode propagates in the ion diamagnetic drift direction, and the poloidal mode number is m ∼ 6-8, determined with a combination of Mirnov coil arrays and 2D fast camera measurement. A high m number induces significant Doppler shift from the background ion flow. The frequency is corrected with both E × B rotation and the ion diamagnetic flow. The corrected frequency is almost consistent with the beta-induced Alfvén eigenmode gap evaluated with the STELLGAP code, although very close to the accumulation point. The mode could also be a global Alfvén eigenmode.

Original languageEnglish
Article number056001
JournalNuclear Fusion
Volume59
Issue number5
DOIs
Publication statusPublished - Mar 14 2019

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low frequencies
electromagnetism
ions
stellarators
neutral beams
coils
cameras
radii
shift

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

Cite this

Zang, L. G., Yamamoto, S., Spong, D. A., Nagasaki, K., Ohshima, S., Kobayashi, S., ... Liu, Y. (2019). Observation of a beam-driven low-frequency mode in Heliotron J. Nuclear Fusion, 59(5), [056001]. https://doi.org/10.1088/1741-4326/ab0197

Observation of a beam-driven low-frequency mode in Heliotron J. / Zang, L. G.; Yamamoto, S.; Spong, D. A.; Nagasaki, K.; Ohshima, S.; Kobayashi, S.; Minami, T.; Lu, X. X.; Nishino, N.; Kado, S.; Adulsiriswad, P.; Okada, H.; Kenmochi, N.; Shigeru, Inagaki; Zhu, J. X.; Weir, G. M.; Mizuuchi, T.; Konoshima, S.; Ishizawa, A.; Yu, D. L.; Shi, Z. B.; Liu, Yi; Yan, L. W.; Li, J. Q.; Yang, Q. W.; Xu, M.; Duan, X. R.; Liu, Yong.

In: Nuclear Fusion, Vol. 59, No. 5, 056001, 14.03.2019.

Research output: Contribution to journalArticle

Zang, LG, Yamamoto, S, Spong, DA, Nagasaki, K, Ohshima, S, Kobayashi, S, Minami, T, Lu, XX, Nishino, N, Kado, S, Adulsiriswad, P, Okada, H, Kenmochi, N, Shigeru, I, Zhu, JX, Weir, GM, Mizuuchi, T, Konoshima, S, Ishizawa, A, Yu, DL, Shi, ZB, Liu, Y, Yan, LW, Li, JQ, Yang, QW, Xu, M, Duan, XR & Liu, Y 2019, 'Observation of a beam-driven low-frequency mode in Heliotron J', Nuclear Fusion, vol. 59, no. 5, 056001. https://doi.org/10.1088/1741-4326/ab0197
Zang LG, Yamamoto S, Spong DA, Nagasaki K, Ohshima S, Kobayashi S et al. Observation of a beam-driven low-frequency mode in Heliotron J. Nuclear Fusion. 2019 Mar 14;59(5). 056001. https://doi.org/10.1088/1741-4326/ab0197
Zang, L. G. ; Yamamoto, S. ; Spong, D. A. ; Nagasaki, K. ; Ohshima, S. ; Kobayashi, S. ; Minami, T. ; Lu, X. X. ; Nishino, N. ; Kado, S. ; Adulsiriswad, P. ; Okada, H. ; Kenmochi, N. ; Shigeru, Inagaki ; Zhu, J. X. ; Weir, G. M. ; Mizuuchi, T. ; Konoshima, S. ; Ishizawa, A. ; Yu, D. L. ; Shi, Z. B. ; Liu, Yi ; Yan, L. W. ; Li, J. Q. ; Yang, Q. W. ; Xu, M. ; Duan, X. R. ; Liu, Yong. / Observation of a beam-driven low-frequency mode in Heliotron J. In: Nuclear Fusion. 2019 ; Vol. 59, No. 5.
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AU - Konoshima, S.

AU - Ishizawa, A.

AU - Yu, D. L.

AU - Shi, Z. B.

AU - Liu, Yi

AU - Yan, L. W.

AU - Li, J. Q.

AU - Yang, Q. W.

AU - Xu, M.

AU - Duan, X. R.

AU - Liu, Yong

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N2 - A low-frequency electromagnetic mode (LF-mode) has been observed in a stellarator/heliotron device, Heliotron J. The LF-mode is observed only in neutral beam heated plasmas with a co-current, which increases the rotational transform. The observed LF-mode peaks at rho = 0.86-0.91, where rho = r/a is the normalized minor radius. The LF-mode propagates in the ion diamagnetic drift direction, and the poloidal mode number is m ∼ 6-8, determined with a combination of Mirnov coil arrays and 2D fast camera measurement. A high m number induces significant Doppler shift from the background ion flow. The frequency is corrected with both E × B rotation and the ion diamagnetic flow. The corrected frequency is almost consistent with the beta-induced Alfvén eigenmode gap evaluated with the STELLGAP code, although very close to the accumulation point. The mode could also be a global Alfvén eigenmode.

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