Evidence for confinement improvement by velocity-shear suppression of edge turbulence

The electrostatic fluctuations are decorrelated in the region of a naturally occurring Eₑ velocity shear close to the outermost closed flux surface of regular Ohmic TEXT discharges. The concomitant local steepening of the density profile and suppression of the fluctuations are consistent with theoretical predictions. The high-confinement mode found in other tokamaks shows, in exaggerated form, similar characteristics, and could thus be related to the same mechanism leading to a locally improved confinement.