Core Poloidal Rotation and Internal Transport Barrier Formation in TFTR
Authors: R.E. Bell, F.M. Levinton, S.H. Batha, E.J. Synakowski, and M.C. Zarnstorff
Impurity poloidal rotation velocities have been measured in the core of TFTR plasmas using a new spectroscopic diagnostic. Two types of transitions to enhanced confinement in reversed shear plasmas are examined. A bifurcation in carbon poloidal rotation is observed to occur before the transition to enhanced confinement for one of these types, while other measured plasmas parameters remain constant. A narrow radial region with reversed poloidal rotation and rotational shear is established 60-100 ms before the transition, and is associated with a large negative radial electric field.