Ishizawa A, Urano D, Nakamura Y, Maeyama S, Watanabe T-H
Graduate School of Energy Science, Kyoto University, Uji 611-0011, Japan.
Department of Physics, Nagoya University, Nagoya 464-8602, Japan.
Phys Rev Lett. 2019 Jul 12;123(2):025003. doi: 10.1103/PhysRevLett.123.025003.
Plasma β dependence of electromagnetic turbulent transport is investigated by means of gyrokinetic simulations with self-consistent change of the equilibrium magnetic field. It is found that energy transport due to ion-temperature-gradient (ITG) driven turbulence does not decrease with increasing β; that is, the ion energy diffusivity does not decrease, and the electron energy diffusivity increases with β. This is because magnetic fluctuations are significantly influenced by the background magnetic field structure change with β by the Pfirsch-Schluter current. The magnetic field change weakens the suppression effect of magnetic perturbations on the growth of the ITG mode, and it also suppresses nonlinear zonal flow production. The influence of the magnetic field change is significant as the global magnetic shear increases.
通过具有自洽平衡磁场变化的回旋动理学模拟，研究了电磁湍流输运对等离子体β的依赖性。研究发现，由离子温度梯度（ITG）驱动的湍流引起的能量输运不会随着β的增加而降低；也就是说，离子能量扩散率不会降低，而电子能量扩散率会随着β的增加而增加。这是因为磁涨落受到背景磁场结构随β通过普菲尔施-施卢特电流变化的显著影响。磁场变化削弱了磁扰动对ITG模增长的抑制作用，同时也抑制了非线性带状流的产生。随着全局磁剪切的增加，磁场变化的影响变得显著。
