title: Self-regulation of E x B flow shear via plasma turbulence.
abstract: The momentum balance has been applied to the ExB flow in the edge region of a reversed field pinch (RFP) configuration. All terms, including those involving fluctuations, have been measured in stationary condition in the edge region of the Extrap-T2R RFP experiment. It is found that the component of the Reynolds stress driven by electrostatic fluctuations is the term playing the major role in driving the shear of the ExB flow to a value marginal for turbulent suppression, so that the results are in favor of a turbulence self-regulating mechanism underlying the momentum balance at the edge. Balancing the sheared flow driving and damping terms, the plasma viscosity is found anomalous and consistent with the diffusivity due to electrostatic turbulence.
authors.affiliation: Consorzio RFX, Associazione EURATOM-ENEA sulla fusione, C.so Stati Uniti 4, I-35127 Padova, Italy.
authors.forename: N
authors.initials: N
authors.lastname: Vianello
authors.forename: E
authors.initials: E
authors.lastname: Spada
authors.forename: V
authors.initials: V
authors.lastname: Antoni
authors.forename: M
authors.initials: M
authors.lastname: Spolaore
authors.forename: G
authors.initials: G
authors.lastname: Serianni
authors.forename: G
authors.initials: G
authors.lastname: Regnoli
authors.forename: R
authors.initials: R
authors.lastname: Cavazzana
authors.forename: H
authors.initials: H
authors.lastname: Bergsåker
authors.forename: J R
authors.initials: JR
authors.lastname: Drake