搜索

x
中国物理学会期刊

J-TEXT托卡马克锯齿振荡期间湍流传播和对称性破缺对边缘剪切流的影响

CSTR: 32037.14.aps.74.20241364

Effects of turbulence spreading and symmetry breaking on edge shear flow during sawtooth cycles in J-TEXT tokamak

CSTR: 32037.14.aps.74.20241364
PDF
PDF English Version
HTML
导出引用
  • 锯齿振荡引起热脉冲和湍流脉冲可以传播到边缘等离子体中增强边缘剪切流并诱发低约束模到高约束模的转换. 在J-TEXT托卡马克上观测了锯齿振荡期间湍流传播和对称性破缺对边缘剪切流的影响. 采用快速往复静电探针阵列测量了边缘等离子体湍流和剪切流等, 观测到锯齿崩塌后, 芯部的热脉冲和湍流传播至边缘等离子体, 且湍流脉冲快于热脉冲. 本文发现了锯齿崩塌后在边缘等离子体中引起湍流对称性破缺, 湍流传播和对称性破缺可以增强湍流雷诺协强, 从而驱动剪切流. 这些结果阐明了锯齿崩塌对边缘湍流和剪切流的增强作用过程.

     

    The effect of sawteeth on plasma performance and transport in the plasma of tokamak is an important problem in the fusion field. Sawtooth oscillations can trigger off heat and turbulence pulses that propagate into the edge plasma, and thus enhancing the edge shear flow and inducing a transition from low confinement mode to high confinement mode. The influences of turbulence spreading and symmetry breaking on edge shear flow with sawtooth crashes are observed in the J-TEXT tokamak. The edge plasma turbulence and shear flow are measured using a fast reciprocating electrostatic probe array. The experimental data are analyzed using some methods such as conditional average and probability distribution function. After sawtooth crashes, the heat and turbulence pulses in the core propagate to the edge, with the turbulence pulse being faster than the heat pulse. The attached figures (a)–(e) show the core electron temperature, and the edge electron temperature, turbulence intensity, turbulence drive and spreading rates, Reynolds stress and its gradient, and shearing rates, respectively. After sawtooth crashes, the edge electron temperature increases and the edge turbulence is enhanced, with turbulence preceding temperature. The enhanced edge turbulence is mainly composed of two parts: the turbulence driven by local gradient and the turbulence spreading from core to edge. The development of the estimated turbulence spreading rate is prior to that of the turbulence driving rate. The increase in the turbulence intensity can cause the turbulent Reynold stress and its gradient to increase, thereby enhancing shear flows and radial electric fields. Turbulence spreading leads the edge Reynolds stresses to develop and the shear flow to be faster than edge electron temperature. The Reynolds stress arises from the symmetry breaking of the turbulence wave number spectrum. After sawtooth collapses, the joint probability density function of radial wave number and poloidal wave number of turbulence intensity becomes highly skewed and anisotropic, exhibiting strong asymmetry, which can be seen in attached figures (f) and (g). The development of turbulence spreading flux at the edge is also prior to the particle flux driven by turbulence, indicating that turbulent energy transport is not simply accompanied by turbulent particle transport. These results show that the turbulence spreading and symmetry breaking can enhance turbulent Reynolds stress, thereby driving shear flows, after sawtooth has crashed.

     

    目录

    /

    返回文章
    返回
    Baidu
    map