Observation of Pedestal Plasma Turbulence on EAST Tokamak

Pedestal plasma turbulence was experimentally studied by microwave reflectometry on EAST tokamak. The characteristics of edge pedestal turbulence during dithering L-H transition, ELM-free H-mode phase and inter-ELM phase have recently been studied on EAST. An edge spatial structure of density fluctu...

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Published inPlasma science & technology Vol. 15; no. 8; pp. 732 - 737
Main Author 高翔 张涛 韩翔 张寿彪 王嵎民 刘子奚 凌必利 李建刚
Format Journal Article
LanguageEnglish
Published 01.08.2013
Subjects
Coherence
Density
Dithering
EAST装置
ELM
Low frequencies
Phase transformations
Plasma turbulence
Precursors
Tokamak devices
微波反射
托卡马克实验
时空演化
立柱
等离子体湍流
高频率
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Summary:Pedestal plasma turbulence was experimentally studied by microwave reflectometry on EAST tokamak. The characteristics of edge pedestal turbulence during dithering L-H transition, ELM-free H-mode phase and inter-ELM phase have recently been studied on EAST. An edge spatial structure of density fluctuation and its dithering temporal evolution is observed for the first time on the EAST tokamak during the L-H transition phase. A coherent mode usually appears during the ELM-free phase prior to the first ELM on EAST tokamak. The mode frequency gradually decreases as the pedestal evolves. Analysis shows that the coherent mode is in the pedestal region inside the separatrix. In plasma with type-III ELMs, a precursor mode before ELM is usually observed. The frequency of the precursor was initially about 150 kHz and gradually decreased till the next ELM. The mode amplitude increases or shows saturation before ELM. In the plasma with compound ELMs composed of high and low frequency ELMs, the precursor was also observed before the high frequency ELM while the harmonic oscillations with frequencies of 20 kHz, 40 kHz and 60 kHz appear before the low frequency ELM.
Bibliography:Pedestal plasma turbulence was experimentally studied by microwave reflectometry on EAST tokamak. The characteristics of edge pedestal turbulence during dithering L-H transition, ELM-free H-mode phase and inter-ELM phase have recently been studied on EAST. An edge spatial structure of density fluctuation and its dithering temporal evolution is observed for the first time on the EAST tokamak during the L-H transition phase. A coherent mode usually appears during the ELM-free phase prior to the first ELM on EAST tokamak. The mode frequency gradually decreases as the pedestal evolves. Analysis shows that the coherent mode is in the pedestal region inside the separatrix. In plasma with type-III ELMs, a precursor mode before ELM is usually observed. The frequency of the precursor was initially about 150 kHz and gradually decreased till the next ELM. The mode amplitude increases or shows saturation before ELM. In the plasma with compound ELMs composed of high and low frequency ELMs, the precursor was also observed before the high frequency ELM while the harmonic oscillations with frequencies of 20 kHz, 40 kHz and 60 kHz appear before the low frequency ELM.
H-mode; pedestal turbulence; reflectometry
GAO Xiang , ZHANG Tao , HAN Xiang , ZHANG Shoubiao , WANG Yumin , LIU Zixi , YANG Yao , LIU Shaocheng , SHI Nan , LING Bili , LI Jiangang , and the EAST team Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
34-1187/TL
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SourceType-Scholarly Journals-1
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ISSN:1009-0630
DOI:10.1088/1009-0630/15/8/03