Mitigation of NBI-driven Alfvén eigenmodes by electron cyclotron heating in the TJ-II stellarator

K. Nagaoka; T. Ido; E. Ascasíbar; T. Estrada; S. Yamamoto; A. V. Melnikov; A. Cappa; C. Hidalgo; M. A. Pedrosa; B. Ph Van Milligen; I. Pastor; M. Liniers; M. A. Ochando; A. Shimizu; L. G. Eliseev; S. Ohshima; K. Mukai; Y. Takeiri

doi:10.1088/0029-5515/53/7/072004

Mitigation of NBI-driven Alfvén eigenmodes by electron cyclotron heating in the TJ-II stellarator

K. Nagaoka, T. Ido, E. Ascasíbar, T. Estrada, S. Yamamoto, A. V. Melnikov, A. Cappa, C. Hidalgo, M. A. Pedrosa, B. Ph Van Milligen, I. Pastor, M. Liniers, M. A. Ochando, A. Shimizu, L. G. Eliseev, S. Ohshima, K. Mukai, Y. Takeiri

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Abstract

Alfvén eigenmode (AE) activity driven by NBI-produced fast ions is observed in TJ-II plasmas. A two-step response of the measured AEs to electron cyclotron heating (ECH) power is seen. In a first step, the continuous character of the unstable AEs changes to a chirping character of the marginally unstable AEs when moderate values of ECH power are applied to the NBI-only-heated plasma. In a second step, a significant reduction of the AE amplitude is observed when the ECH power is doubled. This stabilizing effect has been experimentally confirmed both on a shot-by-shot basis and along a single discharge by means of ECH modulation. The observed stabilizing effect is stronger with on-axis ECH than with off-axis ECH power injection.

Original language	English
Article number	072004
Journal	Nuclear Fusion
Volume	53
Issue number	7
DOIs	https://doi.org/10.1088/0029-5515/53/7/072004
Publication status	Published - Jul 1 2013
Externally published	Yes

All Science Journal Classification (ASJC) codes

Nuclear and High Energy Physics
Condensed Matter Physics

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10.1088/0029-5515/53/7/072004

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Nagaoka, K., Ido, T., Ascasíbar, E., Estrada, T., Yamamoto, S., Melnikov, A. V., Cappa, A., Hidalgo, C., Pedrosa, M. A., Van Milligen, B. P., Pastor, I., Liniers, M., Ochando, M. A., Shimizu, A., Eliseev, L. G., Ohshima, S., Mukai, K., & Takeiri, Y. (2013). Mitigation of NBI-driven Alfvén eigenmodes by electron cyclotron heating in the TJ-II stellarator. Nuclear Fusion, 53(7), Article 072004. https://doi.org/10.1088/0029-5515/53/7/072004

Nagaoka, K, Ido, T, Ascasíbar, E, Estrada, T, Yamamoto, S, Melnikov, AV, Cappa, A, Hidalgo, C, Pedrosa, MA, Van Milligen, BP, Pastor, I, Liniers, M, Ochando, MA, Shimizu, A, Eliseev, LG, Ohshima, S, Mukai, K & Takeiri, Y 2013, 'Mitigation of NBI-driven Alfvén eigenmodes by electron cyclotron heating in the TJ-II stellarator', Nuclear Fusion, vol. 53, no. 7, 072004. https://doi.org/10.1088/0029-5515/53/7/072004

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title = "Mitigation of NBI-driven Alfv{\'e}n eigenmodes by electron cyclotron heating in the TJ-II stellarator",

abstract = "Alfv{\'e}n eigenmode (AE) activity driven by NBI-produced fast ions is observed in TJ-II plasmas. A two-step response of the measured AEs to electron cyclotron heating (ECH) power is seen. In a first step, the continuous character of the unstable AEs changes to a chirping character of the marginally unstable AEs when moderate values of ECH power are applied to the NBI-only-heated plasma. In a second step, a significant reduction of the AE amplitude is observed when the ECH power is doubled. This stabilizing effect has been experimentally confirmed both on a shot-by-shot basis and along a single discharge by means of ECH modulation. The observed stabilizing effect is stronger with on-axis ECH than with off-axis ECH power injection.",

author = "K. Nagaoka and T. Ido and E. Ascas{\'i}bar and T. Estrada and S. Yamamoto and Melnikov, {A. V.} and A. Cappa and C. Hidalgo and Pedrosa, {M. A.} and {Van Milligen}, {B. Ph} and I. Pastor and M. Liniers and Ochando, {M. A.} and A. Shimizu and Eliseev, {L. G.} and S. Ohshima and K. Mukai and Y. Takeiri",

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doi = "10.1088/0029-5515/53/7/072004",

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T1 - Mitigation of NBI-driven Alfvén eigenmodes by electron cyclotron heating in the TJ-II stellarator

AU - Nagaoka, K.

AU - Ido, T.

AU - Ascasíbar, E.

AU - Estrada, T.

AU - Yamamoto, S.

AU - Melnikov, A. V.

AU - Cappa, A.

AU - Hidalgo, C.

AU - Pedrosa, M. A.

AU - Van Milligen, B. Ph

AU - Pastor, I.

AU - Liniers, M.

AU - Ochando, M. A.

AU - Shimizu, A.

AU - Eliseev, L. G.

AU - Ohshima, S.

AU - Mukai, K.

AU - Takeiri, Y.

PY - 2013/7/1

Y1 - 2013/7/1

N2 - Alfvén eigenmode (AE) activity driven by NBI-produced fast ions is observed in TJ-II plasmas. A two-step response of the measured AEs to electron cyclotron heating (ECH) power is seen. In a first step, the continuous character of the unstable AEs changes to a chirping character of the marginally unstable AEs when moderate values of ECH power are applied to the NBI-only-heated plasma. In a second step, a significant reduction of the AE amplitude is observed when the ECH power is doubled. This stabilizing effect has been experimentally confirmed both on a shot-by-shot basis and along a single discharge by means of ECH modulation. The observed stabilizing effect is stronger with on-axis ECH than with off-axis ECH power injection.

AB - Alfvén eigenmode (AE) activity driven by NBI-produced fast ions is observed in TJ-II plasmas. A two-step response of the measured AEs to electron cyclotron heating (ECH) power is seen. In a first step, the continuous character of the unstable AEs changes to a chirping character of the marginally unstable AEs when moderate values of ECH power are applied to the NBI-only-heated plasma. In a second step, a significant reduction of the AE amplitude is observed when the ECH power is doubled. This stabilizing effect has been experimentally confirmed both on a shot-by-shot basis and along a single discharge by means of ECH modulation. The observed stabilizing effect is stronger with on-axis ECH than with off-axis ECH power injection.

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JO - Nuclear Fusion

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ER -

Mitigation of NBI-driven Alfvén eigenmodes by electron cyclotron heating in the TJ-II stellarator

Abstract

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