Effects of parallel dynamics on vortex structures in electron temperature gradient driven turbulence

Journal Article · Sat Jan 15 00:00:00 EST 2011 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3535584· OSTI ID:21532166

Nakata, M ^[1]; Watanabe, T -H ^[1]; Sugama, H ^[2]; Horton, W ^[3]

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1. Graduate University for Advanced Studies, Toki, Gifu 509-5292 (Japan)
2. National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan)
3. Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States)

Vortex structures and related heat transport properties in slab electron temperature gradient (ETG) driven turbulence are comprehensively investigated by means of nonlinear gyrokinetic Vlasov simulations, with the aim of elucidating the underlying physical mechanisms of the transition from turbulent to coherent states. Numerical results show three different types of vortex structures, i.e., coherent vortex streets accompanied with the transport reduction, turbulent vortices with steady transport, and a zonal-flow-dominated state, depending on the relative magnitude of the parallel compression to the diamagnetic drift. In particular, the formation of coherent vortex streets is correlated with the strong generation of zonal flows for the cases with weak parallel compression, even though the maximum growth rate of linear ETG modes is relatively large. The zonal flow generation in the ETG turbulence is investigated by the modulational instability analysis with a truncated fluid model, where the parallel dynamics such as acoustic modes for electrons is incorporated. The modulational instability for zonal flows is found to be stabilized by the effect of the finite parallel compression. The theoretical analysis qualitatively agrees with secondary growth of zonal flows found in the slab ETG turbulence simulations, where the transition of vortex structures is observed.

• OSTI ID: 21532166
• Journal Information: Physics of Plasmas, Vol. 18, Issue 1; Other Information: DOI: 10.1063/1.3535584; (c) 2011 American Institute of Physics; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BOLTZMANN-VLASOV EQUATION
COMPRESSION
ELECTRON TEMPERATURE
HEAT TRANSFER
NONLINEAR PROBLEMS
PLASMA DIAMAGNETISM
PLASMA SIMULATION
TEMPERATURE GRADIENTS
TURBULENCE
VORTICES
DIAMAGNETISM
DIFFERENTIAL EQUATIONS
ENERGY TRANSFER
EQUATIONS
MAGNETISM
PARTIAL DIFFERENTIAL EQUATIONS
SIMULATION