title: Nonlinear dynamics of transport barrier relaxations in tokamak edge plasmas.
abstract: A new mechanism for intermittent relaxations of transport barriers is found by using three dimensional fluid turbulence simulations. This mechanism is generic since it only requires a stationary E x B shear flow. It is found here that if the flow shear increases faster than linearly with heating power, the relaxation frequency decreases with power. An analytical study reveals that this nonlinear dynamics is governed by a time delay for effective velocity shear stabilization.
authors.affiliation: Equipe Dynamique des Systèmes Complexes, LPIIM, CNRS-Université de Provence, Centre de St. Jérôme, Case 321, 13397 Marseille Cedex 20, France.
authors.forename: P
authors.initials: P
authors.lastname: Beyer
authors.forename: S
authors.initials: S
authors.lastname: Benkadda
authors.forename: G
authors.initials: G
authors.lastname: Fuhr-Chaudier
authors.forename: X
authors.initials: X
authors.lastname: Garbet
authors.forename: Ph
authors.initials: P
authors.lastname: Ghendrih
authors.forename: Y
authors.initials: Y
authors.lastname: Sarazin