On the ρ∗ scaling of intrinsic rotation in C-Mod plasmas with edge transport barriers

Changes in the core intrinsic toroidal rotation velocity following L- to H- and L- to I-mode transitions have been investigated in Alcator C-Mod tokamak plasmas. The magnitude of the co-current rotation increments is found to increase with the pedestal temperature gradient and q95, and to decrease with toroidal magnetic field. These results are captured quantitatively by a model of fluctuation entropy balance which gives the Mach number Mi∼=ρ∗/2Ls/LT∼∇Tq95/BT in an ITG turbulence dominant regime. The agreement between experiment and theory gives confidence for extrapolation to future devices in similar operational regimes. Core thermal Mach numbers of ∼0.07 and ∼0.2 are expected for ITER and ARC, respectively.本研究针对阿尔卡特C-Mod（Alcator C-Mod）托卡马克等离子体中，低约束模（L-mode）至高约束模（H-mode）以及低约束模（L-mode）至I型约束模（I-mode）转变后的核心本征环向旋转速度变化展开了系统性探究。 研究发现，同向旋转增量的幅值随台基温度梯度与q95参数的升高而增大，随环向磁场强度的提升而减小。 上述实验结果可通过涨落熵平衡模型实现定量复现；在离子温度梯度（Ion Temperature Gradient, ITG）湍流主导的运行区域中，该模型给出马赫数满足 $M_i ≈ ρ^*/2L_s/L_T ≈ ∇T q_{95}/B_T$。 实验与理论的良好吻合为在相似运行工况下外推至未来聚变装置提供了坚实的置信依据。 国际热核聚变实验堆（International Thermonuclear Experimental Reactor, ITER）与先进研究循环聚变装置（Advanced Research Cycle, ARC）的核心热马赫数预计分别约为0.07与0.2。