中国物理B ›› 2022, Vol. 31 ›› Issue (9): 95201-095201.doi: 10.1088/1674-1056/ac67c2

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Parametric decay instabilities of lower hybrid waves on CFETR

Taotao Zhou(周涛涛)1,2, Nong Xiang(项农)1,3,†, Chunyun Gan(甘春芸)1,3,‡, Guozhang Jia(贾国章)1,3, and Jiale Chen(陈佳乐)1,3   

  1. 1 Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China;
    2 University of Science and Technology of China, Hefei 230026, China;
    3 Centre of Magnetic Fusion Theory, Chinese Academy of Sciences, Hefei 230031, China
  • 收稿日期:2022-01-20 修回日期:2022-04-01 接受日期:2022-04-18 出版日期:2022-08-19 发布日期:2022-08-19
  • 通讯作者: Nong Xiang, Chunyun Gan E-mail:xiangn@ipp.ac.cn;cygan@ipp.ac.cn
  • 基金资助:
    Project supported by the National Key Research and Development Program of China (Grant Nos. 2017YFE0300406 and 2019YFE00308050) and the National Natural Science Foundation of China (Grant Nos. 11975272, 12175274, 12005258, and 11705236). We sincerely appreciate the data support from the CFETR physics team.

Parametric decay instabilities of lower hybrid waves on CFETR

Taotao Zhou(周涛涛)1,2, Nong Xiang(项农)1,3,†, Chunyun Gan(甘春芸)1,3,‡, Guozhang Jia(贾国章)1,3, and Jiale Chen(陈佳乐)1,3   

  1. 1 Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China;
    2 University of Science and Technology of China, Hefei 230026, China;
    3 Centre of Magnetic Fusion Theory, Chinese Academy of Sciences, Hefei 230031, China
  • Received:2022-01-20 Revised:2022-04-01 Accepted:2022-04-18 Online:2022-08-19 Published:2022-08-19
  • Contact: Nong Xiang, Chunyun Gan E-mail:xiangn@ipp.ac.cn;cygan@ipp.ac.cn
  • Supported by:
    Project supported by the National Key Research and Development Program of China (Grant Nos. 2017YFE0300406 and 2019YFE00308050) and the National Natural Science Foundation of China (Grant Nos. 11975272, 12175274, 12005258, and 11705236). We sincerely appreciate the data support from the CFETR physics team.

摘要: The lower hybrid current drive is a potential candidate for sustaining plasma current in tokamak steady-state operations, which could be used in China Fusion Engineering Test Reactor (CFETR) with input power up to a few tens of megawatts. Such high input power could trigger the well-known parametric instabilities (PIs) at the plasma edge affecting the propagation and absorption of the lower hybrid pump waves. By analytically solving the nonlinear dispersion relation describing PIs, an explicit expression of the PI growth rate is obtained and analyzed in detail. It is found that pressure is the key parameter determining the PI characteristics. Ion sound quasi-mode is the dominant decay channel in the low-pressure regime, while the ion cyclotron quasi-mode (ICQM), as well as its harmonics, becomes dominant in the intermediate regime. In the high-pressure regime, only one mixed channel is found, which is related to Landau damping by free-streaming ions. Analytical expressions of growth rates of these decay channels are also obtained to show the parameter dependence at different pressure limits. The above analytical results are used to estimate the PIs on a typical profile of CFETR, and verified by corresponding numerical calculations. ICQM is found to be the strongest decay channel with a considerable growth rate for CFETR.

关键词: lower hybrid, parametric instability, CFETR

Abstract: The lower hybrid current drive is a potential candidate for sustaining plasma current in tokamak steady-state operations, which could be used in China Fusion Engineering Test Reactor (CFETR) with input power up to a few tens of megawatts. Such high input power could trigger the well-known parametric instabilities (PIs) at the plasma edge affecting the propagation and absorption of the lower hybrid pump waves. By analytically solving the nonlinear dispersion relation describing PIs, an explicit expression of the PI growth rate is obtained and analyzed in detail. It is found that pressure is the key parameter determining the PI characteristics. Ion sound quasi-mode is the dominant decay channel in the low-pressure regime, while the ion cyclotron quasi-mode (ICQM), as well as its harmonics, becomes dominant in the intermediate regime. In the high-pressure regime, only one mixed channel is found, which is related to Landau damping by free-streaming ions. Analytical expressions of growth rates of these decay channels are also obtained to show the parameter dependence at different pressure limits. The above analytical results are used to estimate the PIs on a typical profile of CFETR, and verified by corresponding numerical calculations. ICQM is found to be the strongest decay channel with a considerable growth rate for CFETR.

Key words: lower hybrid, parametric instability, CFETR

中图分类号:  (Electromagnetic waves (e.g., electron-cyclotron, Whistler, Bernstein, upper hybrid, lower hybrid))

  • 52.35.Hr
52.35.Mw (Nonlinear phenomena: waves, wave propagation, and other interactions (including parametric effects, mode coupling, ponderomotive effects, etc.)) 52.55.Fa (Tokamaks, spherical tokamaks)