The role of turbulence stabilization by sheared E × B flow isanalysed for different types of internal transport barrier (ITB) in JET discharges.After the ITB formation, the shearing rate ωs is found to consistently exceed arather crude estimate for the ion temperature gradient driven turbulence. The roles playedby toroidal plasma rotation and by density and temperature gradients in both the radialelectric field Er and the shearing rate ωs are evaluated. It turns out that themajor contribution in triggering the positive feedback leading to ITB onset is given bythe toroidal rotation.
Efficiency of transport suppression due to E×B flowshear - a parameter study