E×B flow shear effects on radial correlation length of turbulence and gyroradius scaling of confinement

The radial correlation length of the turbulence responsible for transport can have a different gyroradius scaling in low (L)‐mode and high (H)‐mode plasmas due to E×B flow shear effects, as predicted by the two‐point nonlinear analysis in general tokamak geometry [Phys. Plasmas 2, 1648 (1995)]. This difference offers a possible understanding of the recent ρ*‐scan experiment results on DIII‐D [Fusion Technol. 8, 441 (1985)] L‐mode and H‐mode plasmas [Phys. Plasmas 2, 2342 (1995)]. Within our model, thermal diffusivity in H‐mode plasmas scales like gyro‐Bohm, independent of the scaling in L‐mode plasmas.