Dynamics of oscillatory plasma flows prior to the H-mode in the HL-2A tokamak

Wulyu ZHONG (钟武律); Xiaolan ZOU (邹晓岚); Zhongbing SHI (石中兵); Xuru DUAN (段旭如); Min XU (许敏); Zengchen YANG (杨曾辰); Peiwan SHI (施培万); Min JIANG (蒋敏); Guoliang XIAO (肖国梁); Xianming SONG (宋显明); Jiaqi DONG (董家齐); Xuantong DING (丁玄同); Yong LIU (刘永); HL-A team (HL-A团队)

doi:10.1088/2058-6272/aa6538

Plasma Science and Technology > 2017 > 19(7): 70501-070501. > DOI: 10.1088/2058-6272/aa6538

Wulyu ZHONG (钟武律), Xiaolan ZOU (邹晓岚), Zhongbing SHI (石中兵), Xuru DUAN (段旭如), Min XU (许敏), Zengchen YANG (杨曾辰), Peiwan SHI (施培万), Min JIANG (蒋敏), Guoliang XIAO (肖国梁), Xianming SONG (宋显明), Jiaqi DONG (董家齐), Xuantong DING (丁玄同), Yong LIU (刘永), HL-A team (HL-A团队). Dynamics of oscillatory plasma flows prior to the H-mode in the HL-2A tokamak[J]. Plasma Science and Technology, 2017, 19(7): 70501-070501. DOI: 10.1088/2058-6272/aa6538

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Dynamics of oscillatory plasma flows prior to the H-mode in the HL-2A tokamak

1 Southwestern Institute of Physics, P O Box 432, Chengdu 610041, People’s Republic of China
2 CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
3 Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027, People’s Republic of China

Funds: This work is partially supported within the framework of the cooperation between the French Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA) and the China National Nuclear Corporation (CNNC). It is partially supported by National Natural Science Foundation of China under Grant Nos. 11305053, 10990213, 10975049, 11475057, 11275062, 11375057 and 11575055, and partially supported by Chinese National Fusion Project for ITER under Grant Nos. 2013GB107000 and 2014GB108000.

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Abstract

Abstract

This paper discusses edge oscillatory plasma flows, geodesic acoustic mode (GAM) and limit cycle oscillations (LCOs), which have been measured by Doppler reflectometry prior to the high confinement mode (H-mode) in the HL-2A tokamak. The complex relations between the flows and background turbulence have been analyzed. It was observed that the GAM and LCO coexist, and these two flows and turbulence have strong nonlinear interactions during the intermediate confinement phase (I-phase). Dynamics of the shear flows and turbulence prior to the H-mode shows that the oscillatory flows quench the turbulence along with the increase of the mean E × B flow at the early stage of the I-phase, then the oscillatory flows are damped and the further increased mean flow takes over the role in turbulence suppression. The reduced turbulent transport results in the formation of a steep edge transport barrier. It suggests that the oscillatory flows can initiate the L–H transition through providing a positive feedback for the increase of the mean E × B flow strength.
- plasma shear flow,
- turbulence,
- L–H transition,
- H-mode,
- microwave reflectometry

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