托卡马克外部能量注入对离子温度梯度湍流及反常输运影响的模拟研究

Micro-turbulence and corresponding anomalous transport is one of the key factors of affecting the magnetic confinement in tokamak plasmas. Thus, how to suppress micro-turbulence effectively and improve the plasma confinement greatly are the essential topics in the international tokamak physical researches. Based on the understanding of the characterizations of the micro-turbulence during the auxiliary heating process, one of the important approaches for obtaining high-confinement mode (H-mode) is to control the micro-turbulence and corresponding anomalous transport through the time arrangement and power distribution of the various auxiliary heating methods and current-driven techniques in tokamak plasmas. According to the various auxiliary heating techniques in EAST and HL-2A, this project plans to investigate the effects of external energy injection on the dynamics of the self-regulation system among ion-temperature-gradient turbulence, low frequency zonal-flow and finite frequency geodesic-acoustic-mode. The key point is the physical mechanism of influence of the time arrangement and power distribution of the various auxiliary heating techniques on the ion-scale turbulence and corresponding anomalous transport. The aim of this project is to provide the theoretical basis for exploring the property of H-mode during the auxiliary heating process and to develop the 3D gyro-fluid simulation codes with independent intellectual property right.

微观湍流及其反常输运是影响Tokamak等离子体约束的关键因素之一。因此如何有效地抑制微观湍流以提高等离子体约束是国际Tokamak物理研究的核心问题之一。理解Tokamak辅助加热时微观湍流的激发特性、并通过不同辅助加热手段和电流驱动技术的时间安排和功率分配对微观湍流及其反常输运进行控制是探索Tokamak高约束运行模式的重要途径之一。本项目拟紧密结合国内Tokamak装置，如EAST、HL-2A上的不同加料技术和加热手段，采用自主开发的三维回旋流体代码，研究Tokamak外部能量注入对电磁离子温度梯度湍流、低频的带状流和有限频率的测地声模（GAM）之间自调节动态演化过程的影响，探索不同加热技术的时间安排和功率分配对离子尺度湍流输运影响的物理机制。本项目的顺利完成将为Tokamak高约束模式实验的探索提供必要的理论依据，同时还将发展和完善一套具有自主知识产权的三维回旋流体数值模拟代码。

项目针对Tokamak等离子体中的电磁离子温度梯度湍流，建立了包含电磁扰动的回旋流体模型，数值开发了相应的线性本征值和非线性初值程序，开展了电磁离子温度梯度湍流特性的模拟研究。通过模拟，我们发现了电磁离子温度梯度湍流中有限频率的带状流所引起的间歇性振荡输运现象；剪切ExB流对电磁离子温度梯度湍流和撕裂模的双重作用；磁扰所激发的短波长电磁离子温度梯度湍流的特性；离子温度梯度湍流中的漂移撕裂模不稳定性；以及反磁剪切位形中的离子温度梯度湍流非线性演化特性等。本项目的研究结果进一步加深了对磁约束等离子体中离子尺度电磁湍流激发特性的理解。通过该项目的资助，课题组已在相关等离子体期刊上发表了多篇SCI科研论文，并发展和完善了一套包含低频带状流、有限频率的测地声模以及电磁离子温度梯度湍流的三维回旋流体程序（包括程序的并行和优化）。目前，该程序还可以用于新经典撕裂模和动理学气球模研究，这为今后开展撕裂模和动理学气球模之间多尺度相互作用的研究奠定了基础。