中国物理B ›› 2023, Vol. 32 ›› Issue (1): 15201-015201.doi: 10.1088/1674-1056/ac70b4

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Linear analysis of plasma pressure-driven mode in reversed shear cylindrical tokamak plasmas

Ding-Zong Zhang(张定宗)1,2, Xu-Ming Feng(冯旭铭)1,2, Jun Ma(马骏)2,†, Wen-Feng Guo(郭文峰)2,‡, Yan-Qing Huang(黄艳清)1, and Hong-Bo Liu(刘洪波)1   

  1. 1 College of Physics and Electronic Engineering, Hengyang Normal University, Hengyang 421008, China;
    2 Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
  • 收稿日期:2022-02-18 修回日期:2022-04-25 接受日期:2022-05-18 出版日期:2022-12-08 发布日期:2022-12-27
  • 通讯作者: Jun Ma, Wen-Feng Guo E-mail:junma@ipp.ac.cn;wfguo@ipp.ac.cn
  • 基金资助:
    Project supported by the Research Foundation of Education Bureau of Hunan Province, China (Grant No. 21B0648), the National Natural Science Foundation of China (Grant Nos. 11805239, 12075282, and 11775268), and the Natural Science Foundation of Hunan Province, China (Grant No. 2019JJ50011).

Linear analysis of plasma pressure-driven mode in reversed shear cylindrical tokamak plasmas

Ding-Zong Zhang(张定宗)1,2, Xu-Ming Feng(冯旭铭)1,2, Jun Ma(马骏)2,†, Wen-Feng Guo(郭文峰)2,‡, Yan-Qing Huang(黄艳清)1, and Hong-Bo Liu(刘洪波)1   

  1. 1 College of Physics and Electronic Engineering, Hengyang Normal University, Hengyang 421008, China;
    2 Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
  • Received:2022-02-18 Revised:2022-04-25 Accepted:2022-05-18 Online:2022-12-08 Published:2022-12-27
  • Contact: Jun Ma, Wen-Feng Guo E-mail:junma@ipp.ac.cn;wfguo@ipp.ac.cn
  • Supported by:
    Project supported by the Research Foundation of Education Bureau of Hunan Province, China (Grant No. 21B0648), the National Natural Science Foundation of China (Grant Nos. 11805239, 12075282, and 11775268), and the Natural Science Foundation of Hunan Province, China (Grant No. 2019JJ50011).

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摘要： The linear behavior of the dominant unstable mode ($m=2$, $n=1$) and its high order harmonics ($m=2n$, $n\ge 2$) are numerically investigated in a reversed magnetic shear cylindrical plasma with two $q=2$ rational surfaces on the basis of the non-reduced magnetohydrodynamics (MHD) equations. The results show that with low beta (beta is defined as the ratio of plasma pressure to magnetic field pressure), the dominant mode is a classical double tearing mode (DTM). However, when the beta is sufficiently large, the mode is driven mainly by plasma pressure. In such a case, both the linear growth rate and mode structures are strongly affected by pressure, while almost independent of the resistivity. This means that the dominant mode undergoes a transition from DTM to pressure-driven mode with the increase of pressure, which is consistent with the experimental result in ASDEX Upgrade. The simulations also show that the distance between two rational surfaces has an important influence on the pressure needed in mode transition. The larger the distance between two rational surfaces, the larger the pressure for driving the mode transition is. Motivated by the phenomena that the high-$m$ modes may dominate over low-$m$ modes at small inter-resonance distance, the high-$m$ modes with different pressures and $q$ profiles are studied too.

关键词: magnetohydrodynamics (MHD), double tearing mode, pressure-driven mode

Abstract: The linear behavior of the dominant unstable mode ($m=2$, $n=1$) and its high order harmonics ($m=2n$, $n\ge 2$) are numerically investigated in a reversed magnetic shear cylindrical plasma with two $q=2$ rational surfaces on the basis of the non-reduced magnetohydrodynamics (MHD) equations. The results show that with low beta (beta is defined as the ratio of plasma pressure to magnetic field pressure), the dominant mode is a classical double tearing mode (DTM). However, when the beta is sufficiently large, the mode is driven mainly by plasma pressure. In such a case, both the linear growth rate and mode structures are strongly affected by pressure, while almost independent of the resistivity. This means that the dominant mode undergoes a transition from DTM to pressure-driven mode with the increase of pressure, which is consistent with the experimental result in ASDEX Upgrade. The simulations also show that the distance between two rational surfaces has an important influence on the pressure needed in mode transition. The larger the distance between two rational surfaces, the larger the pressure for driving the mode transition is. Motivated by the phenomena that the high-$m$ modes may dominate over low-$m$ modes at small inter-resonance distance, the high-$m$ modes with different pressures and $q$ profiles are studied too.

Key words: magnetohydrodynamics (MHD), double tearing mode, pressure-driven mode

中图分类号:  (Ideal and resistive MHD modes; kinetic modes)

  • 52.55.Tn
52.65.-y (Plasma simulation) 52.35.Py (Macroinstabilities (hydromagnetic, e.g., kink, fire-hose, mirror, ballooning, tearing, trapped-particle, flute, Rayleigh-Taylor, etc.)) 52.30.Cv (Magnetohydrodynamics (including electron magnetohydrodynamics))