Li Wenyang, Li Jingchun, Lin Z, Dong J Q, Luo J T, Liu Yong
Shenzhen Key Laboratory of Nuclear and Radiation Safety, Institute for Advanced Study in Nuclear Energy and Safety, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China.
School of Physics, Nankai University, Tianjin, 300071, China.
Sci Rep. 2024 Oct 25;14(1):25362. doi: 10.1038/s41598-024-75268-6.
The characteristics of ion-scale turbulence in the presence of a magnetic island are numerically investigated using a gyrokinetic model in fusion plasma. We observe that in the absence of the usual ion temperature gradient (ITG) drive gradient, a magnetic island and its flatten effect could drive ITG instability. The magnetic island (MI) not only drives high-n modes of ITG instability but also induces low-n modes of vortex flow. Moreover, as the magnetic island width increases, the width of the vortex flow also increases. This implies that wider islands may more easily induce vortex flows. The study further indicates that the saturated amplitude and transport level of MI-induced ITG turbulence vary with different magnetic island widths. In general, larger magnetic islands enhance both particle and heat transport. When the magnetic island width reaches to 21ρ, the turbulence-driven transport becomes the same level with the cases that ITG is driven by pressure gradients. Our findings indicate the presence of intricate nonlinear effects in the modulation of plasma turbulence by MIs. These effects are of significant importance for comprehending the phenomenon of nonlinear coupling in forthcoming tokamaks such as ITER.
利用聚变等离子体中的陀螺动力学模型，对存在磁岛时离子尺度湍流的特性进行了数值研究。我们观察到，在没有通常的离子温度梯度（ITG）驱动梯度的情况下，磁岛及其展平效应会驱动ITG不稳定性。磁岛（MI）不仅驱动ITG不稳定性的高n模，还会诱导低n模的涡旋流。此外，随着磁岛宽度增加，涡旋流的宽度也增加。这意味着更宽的磁岛可能更容易诱导涡旋流。该研究进一步表明，MI诱导的ITG湍流的饱和幅度和输运水平随不同的磁岛宽度而变化。一般来说，更大的磁岛会增强粒子和热输运。当磁岛宽度达到21ρ时，湍流驱动的输运与由压力梯度驱动ITG的情况处于同一水平。我们的研究结果表明，磁岛在调制等离子体湍流中存在复杂的非线性效应。这些效应对于理解诸如ITER等未来托卡马克中的非线性耦合现象具有重要意义。
