Physics of Intrinsic Rotation in Flux-Driven ITG Turbulence

Ku, S ; Dimond, P H ; Dif-Pradalier, G ; Kwon, J M ; Sarazin, Y ; Hahm, T S ; Garbet, X ; Chang, C S ; Latu, G ; Yoon, E S ; Ghendrih, Ph ; Yi, S ; Strugarek, A ; Solomon, W

关键词: BOUNDARY CONDITIONS;    DISTRIBUTION FUNCTIONS;    FLUCTUATIONS;    HEAT FLUX;    ION TEMPERATURE;    MACH NUMBER;    PHYSICS;    PROBABILITY;    ROTATION;    SHEAR;    SYMMETRY;    TORQUE;    TRANSPORT;    TURBULENCE Tokamaks;    Turbulence;    Transport Theory;   

DOI  :  10.2172/1035870
RP-ID  :  PPPL-4740
PID  :  OSTI ID: 1035870
Others  :  TRN: US1201751

学科分类：原子、分子光学和等离子物理

美国|英语

来源: SciTech Connect

【 摘 要 】

Global, heat flux-driven ITG gyrokinetic simulations which manifest the formation of macroscopic, mean toroidal flow profiles with peak thermal Mach number 0.05, are reported. Both a particle-in-cell (XGC1p) and a semi-Lagrangian (GYSELA) approach are utilized without a priori assumptions of scale-separation between turbulence and mean fields. Flux-driven ITG simulations with different edge flow boundary conditions show in both approaches the development of net unidirectional intrinsic rotation in the co-current direction. Intrinsic torque is shown to scale approximately linearly with the inverse scale length of the ion temperature gradient. External momentum input is shown to effectively cancel the intrinsic rotation profile, thus confirming the existence of a local residual stress and intrinsic torque. Fluctuation intensity, intrinsic torque and mean flow are demonstrated to develop inwards from the boundary. The measured correlations between residual stress and two fluctuation spectrum symmetry breakers, namely E x B shear and intensity gradient, are similar. Avalanches of (positive) heat flux, which propagate either outwards or inwards, are correlated with avalanches of (negative) parallel momentum flux, so that outward transport of heat and inward transport of parallel momentum are correlated and mediated by avalanches. The probability distribution functions of the outward heat flux and the inward momentum flux show strong structural similarity