Local observations of fast ion responses to energetic particle modes using a directional probe in the Compact Helical System (CHS)

K. Nagaoka; M. Isobe; K. Toi; K. Goto; T. Ito; Y. Todo; M. Osakabe; S. Ohshima; A. Shimizu; A. Fujisawa; H. Nakano; Y. Takeiri; K. Y. Watanabe; T. Akiyama; Y. Yoshimura; C. Suzuki; S. Nishimura; K. Matsuoka; S. Okamura

doi:10.1088/0029-5515/48/8/084005

Local observations of fast ion responses to energetic particle modes using a directional probe in the Compact Helical System (CHS)

K. Nagaoka, M. Isobe, K. Toi, K. Goto, T. Ito, Y. Todo, M. Osakabe, S. Ohshima, A. Shimizu, A. Fujisawa, H. Nakano, Y. Takeiri, K. Y. Watanabe, T. Akiyama, Y. Yoshimura, C. Suzuki, S. Nishimura, K. Matsuoka, S. Okamura

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Abstract

Bursting energetic particle mode (EPM) and fast ion loss induced by the EPM have been observed and experimentally investigated in the Compact Helical System (CHS). A directional probe method was newly applied to neutral beam heated plasmas for fast ion measurement, and it successfully revealed fast ion behaviour inside the last closed flux surface (LCFS) during bursting EPMs. A convective oscillation was observed only inside the LCFS, and drives little loss of fast ions. An anomalous loss of fast ions produced by the phase difference between the fast ion oscillation and the EPM with m = 3/n = 2 was observed in the outward shifted configurations. Another anomalous loss of fast ions due to EPMs with m = 2/n = 1 was also observed in the inward shifted configuration. The characteristics of the fast-ion-loss flux are different from those observed in the outward shifted configurations, and the loss mechanism seems to be related to a mode mixture between the EPM and a low frequency mode.

Original language	English
Article number	084005
Journal	Nuclear Fusion
Volume	48
Issue number	8
DOIs	https://doi.org/10.1088/0029-5515/48/8/084005
Publication status	Published - Aug 1 2008
Externally published	Yes

All Science Journal Classification (ASJC) codes

Nuclear and High Energy Physics
Condensed Matter Physics

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10.1088/0029-5515/48/8/084005

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Nagaoka, K., Isobe, M., Toi, K., Goto, K., Ito, T., Todo, Y., Osakabe, M., Ohshima, S., Shimizu, A., Fujisawa, A., Nakano, H., Takeiri, Y., Watanabe, K. Y., Akiyama, T., Yoshimura, Y., Suzuki, C., Nishimura, S., Matsuoka, K., & Okamura, S. (2008). Local observations of fast ion responses to energetic particle modes using a directional probe in the Compact Helical System (CHS). Nuclear Fusion, 48(8), [084005]. https://doi.org/10.1088/0029-5515/48/8/084005

Nagaoka, K, Isobe, M, Toi, K, Goto, K, Ito, T, Todo, Y, Osakabe, M, Ohshima, S, Shimizu, A, Fujisawa, A, Nakano, H, Takeiri, Y, Watanabe, KY, Akiyama, T, Yoshimura, Y, Suzuki, C, Nishimura, S, Matsuoka, K & Okamura, S 2008, 'Local observations of fast ion responses to energetic particle modes using a directional probe in the Compact Helical System (CHS)', Nuclear Fusion, vol. 48, no. 8, 084005. https://doi.org/10.1088/0029-5515/48/8/084005

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title = "Local observations of fast ion responses to energetic particle modes using a directional probe in the Compact Helical System (CHS)",

abstract = "Bursting energetic particle mode (EPM) and fast ion loss induced by the EPM have been observed and experimentally investigated in the Compact Helical System (CHS). A directional probe method was newly applied to neutral beam heated plasmas for fast ion measurement, and it successfully revealed fast ion behaviour inside the last closed flux surface (LCFS) during bursting EPMs. A convective oscillation was observed only inside the LCFS, and drives little loss of fast ions. An anomalous loss of fast ions produced by the phase difference between the fast ion oscillation and the EPM with m = 3/n = 2 was observed in the outward shifted configurations. Another anomalous loss of fast ions due to EPMs with m = 2/n = 1 was also observed in the inward shifted configuration. The characteristics of the fast-ion-loss flux are different from those observed in the outward shifted configurations, and the loss mechanism seems to be related to a mode mixture between the EPM and a low frequency mode.",

author = "K. Nagaoka and M. Isobe and K. Toi and K. Goto and T. Ito and Y. Todo and M. Osakabe and S. Ohshima and A. Shimizu and A. Fujisawa and H. Nakano and Y. Takeiri and Watanabe, {K. Y.} and T. Akiyama and Y. Yoshimura and C. Suzuki and S. Nishimura and K. Matsuoka and S. Okamura",

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doi = "10.1088/0029-5515/48/8/084005",

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AU - Nagaoka, K.

AU - Isobe, M.

AU - Toi, K.

AU - Goto, K.

AU - Ito, T.

AU - Todo, Y.

AU - Osakabe, M.

AU - Ohshima, S.

AU - Shimizu, A.

AU - Fujisawa, A.

AU - Nakano, H.

AU - Takeiri, Y.

AU - Watanabe, K. Y.

AU - Akiyama, T.

AU - Yoshimura, Y.

AU - Suzuki, C.

AU - Nishimura, S.

AU - Matsuoka, K.

AU - Okamura, S.

PY - 2008/8/1

Y1 - 2008/8/1

N2 - Bursting energetic particle mode (EPM) and fast ion loss induced by the EPM have been observed and experimentally investigated in the Compact Helical System (CHS). A directional probe method was newly applied to neutral beam heated plasmas for fast ion measurement, and it successfully revealed fast ion behaviour inside the last closed flux surface (LCFS) during bursting EPMs. A convective oscillation was observed only inside the LCFS, and drives little loss of fast ions. An anomalous loss of fast ions produced by the phase difference between the fast ion oscillation and the EPM with m = 3/n = 2 was observed in the outward shifted configurations. Another anomalous loss of fast ions due to EPMs with m = 2/n = 1 was also observed in the inward shifted configuration. The characteristics of the fast-ion-loss flux are different from those observed in the outward shifted configurations, and the loss mechanism seems to be related to a mode mixture between the EPM and a low frequency mode.

AB - Bursting energetic particle mode (EPM) and fast ion loss induced by the EPM have been observed and experimentally investigated in the Compact Helical System (CHS). A directional probe method was newly applied to neutral beam heated plasmas for fast ion measurement, and it successfully revealed fast ion behaviour inside the last closed flux surface (LCFS) during bursting EPMs. A convective oscillation was observed only inside the LCFS, and drives little loss of fast ions. An anomalous loss of fast ions produced by the phase difference between the fast ion oscillation and the EPM with m = 3/n = 2 was observed in the outward shifted configurations. Another anomalous loss of fast ions due to EPMs with m = 2/n = 1 was also observed in the inward shifted configuration. The characteristics of the fast-ion-loss flux are different from those observed in the outward shifted configurations, and the loss mechanism seems to be related to a mode mixture between the EPM and a low frequency mode.

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Local observations of fast ion responses to energetic particle modes using a directional probe in the Compact Helical System (CHS)

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