Positive radial electric fields have been created at the edge of theTEXTOR tokamak plasma using an electrode. The electric field induces athin (δr∼1.5 cm), E × B driven layer at the edge rotating poloidally at12-20 km/s and featuring high shear. Concomitant changes in thedensity and poloidal electric field fluctuations and their cross-phasein the shear layer result in suppression of radial turbulentparticle transport, even at low radial electric fieldstrength. Temperature fluctuations are reduced, resulting indiminished turbulent heat flux. As turbulent particle transport isquenched, the particle confinement time τp increases by a factor of 2 andthe energy confinement time τE by 20%. Turbulent transport accountsfor ∼50% of the total particle flux. Both the cross-phase and thedensity fluctuations are sensitive to the sign of ∇Er.
Broadband fluctuations and particle transport in the edge plasma during ECRH in DITE