The nonlinear coupling between gyroradius scale turbulence and mesoscale magnetic islands in fusion plasmas

Hornsby, W A; Peeters, A G; Snodin, A P; Casson, F J; Camenen, Y; Szepesi, G; Siccinio, M; Poli, E

doi:10.1063/1.3467502

Title: The nonlinear coupling between gyroradius scale turbulence and mesoscale magnetic islands in fusion plasmas

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Abstract

The interaction between small scale turbulence (of the order of the ion Larmor radius) and mesoscale magnetic islands is investigated within the gyrokinetic framework. Turbulence, driven by background temperature and density gradients, over nonlinear mode coupling, pumps energy into long wavelength modes, and can result in an electrostatic vortex mode that coincides with the magnetic island. The strength of the vortex is strongly enhanced by the modified plasma flow response connected with the change in topology, and the transport it generates can compete with the parallel motion along the perturbed magnetic field. Despite the stabilizing effect of sheared plasma flows in and around the island, the net effect of the island is a degradation of the confinement. When density and temperature gradients inside the island are below the threshold for turbulence generation, turbulent fluctuations still persist through turbulence convection and spreading. The latter mechanisms then generate a finite transport flux and, consequently, a finite pressure gradient in the island. A finite radial temperature gradient inside the island is also shown to persist due to the trapped particles, which do not move along the field around the island. In the low collisionality regime, the finite gradient in the trapped population leadsmore »« less

Authors:

Hornsby, W A; Peeters, A G; Snodin, A P; Casson, F J; Camenen, Y; Szepesi, G ^[1]; Siccinio, M; Poli, E ^[2]

Department of Physics, Centre for Fusion, Space, and Astrophysics, University of Warwick, Coventry (United Kingdom)
Max-Planck-Institut fuer Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching bei Muenchen (Germany)

Publication Date:: Wed Sep 15 00:00:00 EDT 2010

OSTI Identifier:: 21432271

Resource Type:: Journal Article

Journal Name:: Physics of Plasmas

Additional Journal Information:: Journal Volume: 17; Journal Issue: 9; Other Information: DOI: 10.1063/1.3467502; (c) 2010 American Institute of Physics; Journal ID: ISSN 1070-664X

Country of Publication:: United States

Language:: English

Subject:: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BOOTSTRAP CURRENT; CONVECTION; COUPLING; ELECTRON TEMPERATURE; ION TEMPERATURE; MAGNETIC ISLANDS; NONLINEAR PROBLEMS; PLASMA; PLASMA DENSITY; PRESSURE GRADIENTS; TEMPERATURE GRADIENTS; TURBULENCE; VORTICES; CURRENTS; ELECTRIC CURRENTS; ENERGY TRANSFER; HEAT TRANSFER; MAGNETIC FIELD CONFIGURATIONS; MASS TRANSFER

Citation Formats


                    Hornsby, W A, Peeters, A G, Snodin, A P, Casson, F J, Camenen, Y, Szepesi, G, Siccinio, M, and Poli, E. The nonlinear coupling between gyroradius scale turbulence and mesoscale magnetic islands in fusion plasmas.  United States: N. p., 2010. 
        Web.  doi:10.1063/1.3467502.

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                    Hornsby, W A, Peeters, A G, Snodin, A P, Casson, F J, Camenen, Y, Szepesi, G, Siccinio, M, & Poli, E. The nonlinear coupling between gyroradius scale turbulence and mesoscale magnetic islands in fusion plasmas.  United States.  https://doi.org/10.1063/1.3467502

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                    Hornsby, W A, Peeters, A G, Snodin, A P, Casson, F J, Camenen, Y, Szepesi, G, Siccinio, M, and Poli, E. 2010.  
        "The nonlinear coupling between gyroradius scale turbulence and mesoscale magnetic islands in fusion plasmas".  United States.  https://doi.org/10.1063/1.3467502.

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@article{osti_21432271,

  title        = {The nonlinear coupling between gyroradius scale turbulence and mesoscale magnetic islands in fusion plasmas},

  author       = {Hornsby, W A and Peeters, A G and Snodin, A P and Casson, F J and Camenen, Y and Szepesi, G and Siccinio, M and Poli, E},

  abstractNote = {The interaction between small scale turbulence (of the order of the ion Larmor radius) and mesoscale magnetic islands is investigated within the gyrokinetic framework. Turbulence, driven by background temperature and density gradients, over nonlinear mode coupling, pumps energy into long wavelength modes, and can result in an electrostatic vortex mode that coincides with the magnetic island. The strength of the vortex is strongly enhanced by the modified plasma flow response connected with the change in topology, and the transport it generates can compete with the parallel motion along the perturbed magnetic field. Despite the stabilizing effect of sheared plasma flows in and around the island, the net effect of the island is a degradation of the confinement. When density and temperature gradients inside the island are below the threshold for turbulence generation, turbulent fluctuations still persist through turbulence convection and spreading. The latter mechanisms then generate a finite transport flux and, consequently, a finite pressure gradient in the island. A finite radial temperature gradient inside the island is also shown to persist due to the trapped particles, which do not move along the field around the island. In the low collisionality regime, the finite gradient in the trapped population leads to the generation of a bootstrap current, which reduces the neoclassical drive.},

  doi          = {10.1063/1.3467502},

  url          = {https://www.osti.gov/biblio/21432271},
  journal      = {Physics of Plasmas},

  issn         = {1070-664X},

  number       = 9,

  volume       = 17,

  place        = {United States},

  year         = {Wed Sep 15 00:00:00 EDT 2010},

  month        = {Wed Sep 15 00:00:00 EDT 2010}

}

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