中国物理B ›› 2022, Vol. 31 ›› Issue (6): 65207-065207.doi: 10.1088/1674-1056/ac6011

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Role of the zonal flow in multi-scale multi-mode turbulence with small-scale shear flow in tokamak plasmas

Hui Li(李慧)1,2, Jiquan Li(李继全)2,†, Zhengxiong Wang(王正汹)1,‡, Lai Wei(魏来)1, and Zhaoqing Hu(胡朝清)2   

  1. 1 Key Laboratory of Materials Modification by Beams of the Ministry of Education, School of Physics, Dalian University of Technology, Dalian 116024, China;
    2 Southwestern Institute of Physics, Chengdu 610041, China
  • 收稿日期:2021-12-23 修回日期:2022-03-14 接受日期:2022-03-23 出版日期:2022-05-17 发布日期:2022-06-07
  • 通讯作者: Jiquan Li, Zhengxiong Wang E-mail:lijq@swip.ac.cn;zxwang@dlut.edu.cn
  • 基金资助:
    Project supported by the National Key Research and Development Program of China (Grant Nos. 2017YFE0301200 and 2017YFE0301201), partially by the National Natural Science Foundation of China (Grant Nos. 11775069 and 11925501), and the Liaoning Revitalization Talents Program (Grant No. XLYC1802009).

Role of the zonal flow in multi-scale multi-mode turbulence with small-scale shear flow in tokamak plasmas

Hui Li(李慧)1,2, Jiquan Li(李继全)2,†, Zhengxiong Wang(王正汹)1,‡, Lai Wei(魏来)1, and Zhaoqing Hu(胡朝清)2   

  1. 1 Key Laboratory of Materials Modification by Beams of the Ministry of Education, School of Physics, Dalian University of Technology, Dalian 116024, China;
    2 Southwestern Institute of Physics, Chengdu 610041, China
  • Received:2021-12-23 Revised:2022-03-14 Accepted:2022-03-23 Online:2022-05-17 Published:2022-06-07
  • Contact: Jiquan Li, Zhengxiong Wang E-mail:lijq@swip.ac.cn;zxwang@dlut.edu.cn
  • Supported by:
    Project supported by the National Key Research and Development Program of China (Grant Nos. 2017YFE0301200 and 2017YFE0301201), partially by the National Natural Science Foundation of China (Grant Nos. 11775069 and 11925501), and the Liaoning Revitalization Talents Program (Grant No. XLYC1802009).

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摘要： The structural characteristics of zonal flows and their roles in the nonlinear interaction of multi-scale multi-mode turbulence are investigated numerically via a self-consistent Landau-fluid model. The multi-mode turbulence here is composed of a shorter wavelength electromagnetic (EM) ion temperature gradient (ITG) mode and a Kelvin-Helmholtz (KH) instability with long wavelengths excited by externally imposed small-scale shear flows. For strong shear flow, a prominent periodic intermittency of fluctuation intensity except for dominant ITG component is revealed in turbulence evolution, which onset time depends on the ion temperature gradient and the shear flow amplitudes corresponding to different KH instabilities. It is identified that the intermittency phenomenon results from the zonal flow dynamics, which is mainly generated by the KH mode and back-reacts on it. It is demonstrated that the odd symmetric components of zonal flow (same symmetry as the external flow) make the radial parity of the KH mode alteration through adjusting the drift velocities at two sides of the resonant surface so that the KH mode becomes bursty first. Afterwards, the ITG intermittency follows due to nonlinear mode coupling. Parametric dependences of the features of the intermittency are elaborated. Finally, associated turbulent heat transport is evaluated.

关键词: drift waves, turbulence, nonlinear phenomena, plasma simulation

Abstract: The structural characteristics of zonal flows and their roles in the nonlinear interaction of multi-scale multi-mode turbulence are investigated numerically via a self-consistent Landau-fluid model. The multi-mode turbulence here is composed of a shorter wavelength electromagnetic (EM) ion temperature gradient (ITG) mode and a Kelvin-Helmholtz (KH) instability with long wavelengths excited by externally imposed small-scale shear flows. For strong shear flow, a prominent periodic intermittency of fluctuation intensity except for dominant ITG component is revealed in turbulence evolution, which onset time depends on the ion temperature gradient and the shear flow amplitudes corresponding to different KH instabilities. It is identified that the intermittency phenomenon results from the zonal flow dynamics, which is mainly generated by the KH mode and back-reacts on it. It is demonstrated that the odd symmetric components of zonal flow (same symmetry as the external flow) make the radial parity of the KH mode alteration through adjusting the drift velocities at two sides of the resonant surface so that the KH mode becomes bursty first. Afterwards, the ITG intermittency follows due to nonlinear mode coupling. Parametric dependences of the features of the intermittency are elaborated. Finally, associated turbulent heat transport is evaluated.

Key words: drift waves, turbulence, nonlinear phenomena, plasma simulation

中图分类号:  (Drift waves)

  • 52.35.Kt
52.35.Ra (Plasma turbulence) 52.35.Mw (Nonlinear phenomena: waves, wave propagation, and other interactions (including parametric effects, mode coupling, ponderomotive effects, etc.)) 52.65.-y (Plasma simulation)