EXB FLOW SHEAR EFFECTS ON RADIAL CORRELATION LENGTH OF TURBULENCE ANDGYRORADIUS SCALING OF CONFINEMENT

The radial correlation length of the turbulence responsible for transp ort can have a different gyroradius scaling in low (L)-mode and high ( H)-mode plasmas due to EXB 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 rho-scan experiment results on DIII-D [Fusion Technol. 8, 441 (1985)] L-mode and H-mode plasmas [Phys. Plasmas 2, 2342 (1995)]. Wit hin our model, thermal diffusivity in H-mode plasmas scales like gyro- Bohm, independent of the scaling in L-mode plasmas. (C) 1996 American Institute of Physics.