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Symmetry breaking in MAST plasma turbulence due to toroidal flow shear
- Source :
- Plasma Physics and Controlled Fusion
- Publication Year :
- 2017
-
Abstract
- The flow shear associated with the differential toroidal rotation of tokamak plasmas breaks an underlying symmetry of the turbulent fluctuations imposed by the up-down symmetry of the magnetic equilibrium. Using experimental Beam-Emission-Spectroscopy (BES) measurements and gyrokinetic simulations, this symmetry breaking in ion-scale turbulence in MAST is shown to manifest itself as a tilt of the spatial correlation function and a finite skew in the distribution of the fluctuating density field. The tilt is a statistical expression of the "shearing" of the turbulent structures by the mean flow. The skewness of the distribution is related to the emergence of long-lived density structures in sheared, near-marginal plasma turbulence. The extent to which these effects are pronounced is argued (with the aid of the simulations) to depend on the distance from the nonlinear stability threshold. Away from the threshold, the symmetry is effectively restored.
- Subjects :
- Physics
Shearing (physics)
Tokamak
Toroid
Turbulence
FOS: Physical sciences
Mechanics
Plasma
Condensed Matter Physics
01 natural sciences
Physics - Plasma Physics
010305 fluids & plasmas
law.invention
Plasma Physics (physics.plasm-ph)
Physics::Fluid Dynamics
Nuclear Energy and Engineering
law
Skewness
Physics::Plasma Physics
0103 physical sciences
Mean flow
Symmetry breaking
010306 general physics
Subjects
Details
- ISSN :
- 07413335, 00295515, and 00344885
- Database :
- OpenAIRE
- Journal :
- Plasma Physics and Controlled Fusion
- Accession number :
- edsair.doi.dedup.....8bb0e698fbb12062ead82522c07041ea
- Full Text :
- https://doi.org/10.1088/1361-6587/aa544b