Zhu Hongxuan, Stoltzfus-Dueck T, Hager R, Ku S, Chang C S
<a href="https://ror.org/03vn1ts68">Princeton Plasma Physics Laboratory</a>, Princeton, New Jersey 08540, USA.
Department of Astrophysical Sciences, <a href="https://ror.org/00hx57361">Princeton University</a>, Princeton, New Jersey 08544, USA.
Phys Rev Lett. 2024 Jul 12;133(2):025101. doi: 10.1103/PhysRevLett.133.025101.
Gyrokinetic tokamak plasmas can exhibit intrinsic toroidal rotation driven by the residual stress. While most studies have attributed the residual stress to the parallel-momentum flux from the turbulent E×B motion, the parallel-momentum flux from the drift-orbit motion (denoted Π_{∥}^{D}) and the E×B-momentum flux from the E×B motion (denoted Π_{E×B}) are often neglected. Here, we use the global total-f gyrokinetic code XGC to study the residual stress in the core and the edge of a DIII-D H-mode plasma. Numerical results show that both Π_{∥}^{D} and Π_{E×B} make up a significant portion of the residual stress. In particular, Π_{∥}^{D} in the core is higher than the collisional neoclassical level in the presence of turbulence, while in the edge it represents an outflux of countercurrent momentum even without turbulence. Using a recently developed "orbit-flux" formulation, we show that the higher-than-neoclassical-level Π_{∥}^{D} in the core is driven by turbulence, while the outflux of countercurrent momentum from the edge is mainly due to collisional ion orbit loss. These results suggest that Π_{∥}^{D} and Π_{E×B} can be important for the study of intrinsic toroidal rotation.
回旋动理学托卡马克等离子体可以表现出由残余应力驱动的本征环向旋转。虽然大多数研究将残余应力归因于湍流E×B运动产生的平行动量通量，但漂移轨道运动产生的平行动量通量（记为Π_{∥}^{D}）和E×B运动产生的E×B动量通量（记为Π_{E×B}）常常被忽略。在此，我们使用全局全f回旋动理学代码XGC来研究DIII-D H模等离子体核心区和边缘区的残余应力。数值结果表明，Π_{∥}^{D}和Π_{E×B}都在残余应力中占很大一部分。特别地，在存在湍流的情况下，核心区的Π_{∥}^{D}高于碰撞新经典水平，而在边缘区，即使没有湍流，它也代表着反向动量的外流。使用最近开发的“轨道通量”公式，我们表明核心区高于新经典水平的Π_{∥}^{D}是由湍流驱动的，而边缘区反向动量的外流主要是由于碰撞离子轨道损失。这些结果表明，Π_{∥}^{D}和Π_{E×B}对于本征环向旋转的研究可能很重要。
