title: Vanishing magnetic shear and electron transport barriers in the RFX-mod reversed field pinch.
abstract: We define the safety factor q for the helical plasmas of the experiment RFX-mod by accounting for the actual three-dimensional nature of the magnetic flux surfaces. Such a profile is not monotonic but goes through a maximum located in the vicinity of the electron transport barriers measured by a high resolution Thomson scattering diagnostic. Helical states with a single axis obtained in viscoresistive magnetohydrodynamic numerical simulations exhibit similar nonmonotonic q profiles provided that the final states are preceded by a magnetic island phase, like in the experiment.
authors.affiliation: Consorzio RFX, Associazione EURATOM-ENEA sulla Fusione Corso Stati Uniti, 4 35127 Padova-Italy.
authors.forename: M
authors.initials: M
authors.lastname: Gobbin
authors.forename: D
authors.initials: D
authors.lastname: Bonfiglio
authors.forename: D F
authors.initials: DF
authors.lastname: Escande
authors.forename: A
authors.initials: A
authors.lastname: Fassina
authors.forename: L
authors.initials: L
authors.lastname: Marrelli
authors.forename: A
authors.initials: A
authors.lastname: Alfier
authors.forename: E
authors.initials: E
authors.lastname: Martines
authors.forename: B
authors.initials: B
authors.lastname: Momo
authors.forename: D
authors.initials: D
authors.lastname: Terranova