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 ~ rho*/2 Ls/Lt ~ gradT q95/Bt in an ITG mode dominant regime.