Spatial structure of low-frequency fluctuations throughout the transition of poloidal flow velocity in edge plasmas of LHD

C. Moon; T. Kobayashi; K. Ida; T. Tokuzawa; C. Hidalgo; M. Yoshinuma; K. Ogawa; K. Itoh; A. Fujisawa

doi:10.1063/1.5098954

Spatial structure of low-frequency fluctuations throughout the transition of poloidal flow velocity in edge plasmas of LHD

C. Moon, T. Kobayashi, K. Ida, T. Tokuzawa, C. Hidalgo, M. Yoshinuma, K. Ogawa, K. Itoh, A. Fujisawa

Research output: Contribution to journal › Article › peer-review

Abstract

It is observed that a low-frequency (∼2 kHz) density fluctuation is excited in a transition of the poloidal flow velocity (V_θ) in the edge magnetic stochastic region of the Large Helical Device plasmas. Furthermore, it is found that the propagation velocity becomes approximately zero in the proximity of the appearance region of the low-frequency fluctuation by using the edge multichannel microwave Doppler reflectometer system. In particular, the low-frequency fluctuation is considered to be transmitted in both directions (inward and outward) away from the excitation position of the fluctuation, which behaves as the precursor of a magnetic fluctuation burst. Afterward, the edge H α signal intensity is sharply increased.

Original language	English
Article number	092302
Journal	Physics of Plasmas
Volume	26
Issue number	9
DOIs	https://doi.org/10.1063/1.5098954
Publication status	Published - Sept 1 2019

All Science Journal Classification (ASJC) codes

Condensed Matter Physics

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10.1063/1.5098954

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title = "Spatial structure of low-frequency fluctuations throughout the transition of poloidal flow velocity in edge plasmas of LHD",

abstract = "It is observed that a low-frequency (∼2 kHz) density fluctuation is excited in a transition of the poloidal flow velocity (Vθ) in the edge magnetic stochastic region of the Large Helical Device plasmas. Furthermore, it is found that the propagation velocity becomes approximately zero in the proximity of the appearance region of the low-frequency fluctuation by using the edge multichannel microwave Doppler reflectometer system. In particular, the low-frequency fluctuation is considered to be transmitted in both directions (inward and outward) away from the excitation position of the fluctuation, which behaves as the precursor of a magnetic fluctuation burst. Afterward, the edge H α signal intensity is sharply increased.",

author = "C. Moon and T. Kobayashi and K. Ida and T. Tokuzawa and C. Hidalgo and M. Yoshinuma and K. Ogawa and K. Itoh and A. Fujisawa",

note = "Funding Information: We thank Professor S. Sakakibara, Professor U. Stroth, and Professor E. Wolfrum for strong support. The authors acknowledge all the members of LHD Experiment Group for their assistance. This work was partly supported by JSPS KAKENHI Grant Nos. 15H02336, 16H02442, 17H06089, and 19K23426. This work was also partly supported by the National Institute for Fusion Science grant administrative budgets (NIFS10ULHH021 and NIFS17KLPH030). Publisher Copyright: {\textcopyright} 2019 Author(s).",

year = "2019",

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doi = "10.1063/1.5098954",

language = "English",

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T1 - Spatial structure of low-frequency fluctuations throughout the transition of poloidal flow velocity in edge plasmas of LHD

AU - Moon, C.

AU - Kobayashi, T.

AU - Ida, K.

AU - Tokuzawa, T.

AU - Hidalgo, C.

AU - Yoshinuma, M.

AU - Ogawa, K.

AU - Itoh, K.

AU - Fujisawa, A.

N1 - Funding Information: We thank Professor S. Sakakibara, Professor U. Stroth, and Professor E. Wolfrum for strong support. The authors acknowledge all the members of LHD Experiment Group for their assistance. This work was partly supported by JSPS KAKENHI Grant Nos. 15H02336, 16H02442, 17H06089, and 19K23426. This work was also partly supported by the National Institute for Fusion Science grant administrative budgets (NIFS10ULHH021 and NIFS17KLPH030). Publisher Copyright: © 2019 Author(s).

PY - 2019/9/1

Y1 - 2019/9/1

N2 - It is observed that a low-frequency (∼2 kHz) density fluctuation is excited in a transition of the poloidal flow velocity (Vθ) in the edge magnetic stochastic region of the Large Helical Device plasmas. Furthermore, it is found that the propagation velocity becomes approximately zero in the proximity of the appearance region of the low-frequency fluctuation by using the edge multichannel microwave Doppler reflectometer system. In particular, the low-frequency fluctuation is considered to be transmitted in both directions (inward and outward) away from the excitation position of the fluctuation, which behaves as the precursor of a magnetic fluctuation burst. Afterward, the edge H α signal intensity is sharply increased.

AB - It is observed that a low-frequency (∼2 kHz) density fluctuation is excited in a transition of the poloidal flow velocity (Vθ) in the edge magnetic stochastic region of the Large Helical Device plasmas. Furthermore, it is found that the propagation velocity becomes approximately zero in the proximity of the appearance region of the low-frequency fluctuation by using the edge multichannel microwave Doppler reflectometer system. In particular, the low-frequency fluctuation is considered to be transmitted in both directions (inward and outward) away from the excitation position of the fluctuation, which behaves as the precursor of a magnetic fluctuation burst. Afterward, the edge H α signal intensity is sharply increased.

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JO - Physics of Plasmas

JF - Physics of Plasmas

IS - 9

M1 - 092302

ER -

Spatial structure of low-frequency fluctuations throughout the transition of poloidal flow velocity in edge plasmas of LHD

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