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Plasma rotation and transport in MAST spherical tokamak

Field, A R; Michael, Clive; Akers, R.J.; Candy, J; Colyer, G; Guttenfelder, W.; Ghim, Y.-c.; Roach, C M; Saarelma, S.; MAST Team, The

Description

The formation of internal transport barriers (ITBs) is investigated in MAST spherical tokamak plasmas. The relative importance of equilibrium flow shear and magnetic shear in their formation and evolution is investigated using data from high-resolution kinetic- and q-profile diagnostics. In L-mode plasmas, with co-current directed NBI heating, ITBs in the momentum and ion thermal channels form in the negative shear region just inside qmin. In the ITB region the anomalous ion thermal transport...[Show more]

dc.contributor.authorField, A R
dc.contributor.authorMichael, Clive
dc.contributor.authorAkers, R.J.
dc.contributor.authorCandy, J
dc.contributor.authorColyer, G
dc.contributor.authorGuttenfelder, W.
dc.contributor.authorGhim, Y.-c.
dc.contributor.authorRoach, C M
dc.contributor.authorSaarelma, S.
dc.contributor.authorMAST Team, The
dc.date.accessioned2015-12-08T22:40:41Z
dc.identifier.issn0029-5515
dc.identifier.urihttp://hdl.handle.net/1885/36600
dc.description.abstractThe formation of internal transport barriers (ITBs) is investigated in MAST spherical tokamak plasmas. The relative importance of equilibrium flow shear and magnetic shear in their formation and evolution is investigated using data from high-resolution kinetic- and q-profile diagnostics. In L-mode plasmas, with co-current directed NBI heating, ITBs in the momentum and ion thermal channels form in the negative shear region just inside qmin. In the ITB region the anomalous ion thermal transport is suppressed, with ion thermal transport close to the neo-classical level, although the electron transport remains anomalous. Linear stability analysis with the gyro-kinetic code GS2 shows that all electrostatic micro-instabilities are stable in the negative magnetic shear region in the core, both with and without flow shear. Outside the ITB, in the region of positive magnetic shear and relatively weak flow shear, electrostatic micro-instabilities become unstable over a wide range of wave numbers. Flow shear reduces the linear growth rates of low-k modes but suppression of ITG modes is incomplete, which is consistent with the observed anomalous ion transport in this region; however, flow shear has little impact on growth rates of high-k, electron-scale modes. With counter-NBI ITBs of greater radial extent form outside qmin due to the broader profile of E × B flow shear produced by the greater prompt fast-ion loss torque.
dc.publisherIOP Publishing
dc.sourceNuclear Fusion
dc.subjectKeywords: Electron transport; Equilibrium flow; Flow shear; High resolution; Internal transport barriers; Ion transports; L-mode plasmas; Linear growth rate; Magnetic shear; Microinstabilities; Negative magnetic shear; Plasma rotations; Q profiles; Relative importa
dc.titlePlasma rotation and transport in MAST spherical tokamak
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume51
dc.date.issued2011
local.identifier.absfor020204 - Plasma Physics; Fusion Plasmas; Electrical Discharges
local.identifier.ariespublicationu4695161xPUB138
local.type.statusPublished Version
local.contributor.affiliationField, A R, EURATOM/CCFE Fusion Association
local.contributor.affiliationMichael, Clive, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationAkers, R.J., EURATOM/UKAEA Fusion Association
local.contributor.affiliationCandy, J, General Atomics
local.contributor.affiliationColyer, G, EURATOM/CCFE Fusion Association
local.contributor.affiliationGuttenfelder, W., Princeton Plasma Physics Laboratory
local.contributor.affiliationGhim, Y.-c., University of Oxford
local.contributor.affiliationRoach, C M, EURATOM/CCFE Fusion Association
local.contributor.affiliationSaarelma, S., EURATOM/UKAEA Fusion Association
local.contributor.affiliationMAST Team, The, EURATOM/CCFE Fusion Assoc.
local.description.embargo2037-12-31
local.bibliographicCitation.issue6
local.bibliographicCitation.startpage063006
local.identifier.doi10.1088/0029-5515/51/6/063006
dc.date.updated2016-02-24T11:18:28Z
local.identifier.scopusID2-s2.0-79957586626
CollectionsANU Research Publications

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