Collisionless kineticfluid model of zonal flows in toroidal plasmas
Abstract
A novel kineticfluid model is presented, which describes collisionless time evolution of zonal flows in tokamaks. In the new zonalflow closure relations, the parallel heat fluxes are written by the sum of short and longtimeevolution parts. The former part is given in the dissipative form of the parallel heat diffusion and relates to collisionless damping processes. The latter is derived from the longtimeaveraged gyrocenter distribution and plays a major role in describing lowfrequency or stationary zonal flows, for which the parallel heat fluxes are expressed in terms of the parallel flow as well as the nonlinearsource and initialcondition terms. It is shown analytically and numerically that, when applied to the zonal flow driven by either ion or electron temperature gradient turbulence, the kineticfluid equations including the new closure relations can reproduce the same longtime zonalflow responses to the initial condition and to the turbulence source as those obtained from the gyrokinetic model.
 Authors:
 National Institute for Fusion Science, Graduate University for Advanced Studies, Toki 5095292 (Japan)
 (United States)
 Publication Date:
 OSTI Identifier:
 20974832
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 2; Other Information: DOI: 10.1063/1.2435329; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; DAMPING; DIFFUSION; DISTRIBUTION; ELECTRON TEMPERATURE; HEAT; HEAT FLUX; ION TEMPERATURE; IONS; NONLINEAR PROBLEMS; PLASMA; PLASMA CONFINEMENT; PLASMA FLUID EQUATIONS; PLASMA SIMULATION; TEMPERATURE GRADIENTS; TOKAMAK DEVICES; TURBULENCE
Citation Formats
Sugama, H., Watanabe, T.H., Horton, W., and Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712. Collisionless kineticfluid model of zonal flows in toroidal plasmas. United States: N. p., 2007.
Web. doi:10.1063/1.2435329.
Sugama, H., Watanabe, T.H., Horton, W., & Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712. Collisionless kineticfluid model of zonal flows in toroidal plasmas. United States. doi:10.1063/1.2435329.
Sugama, H., Watanabe, T.H., Horton, W., and Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712. Thu .
"Collisionless kineticfluid model of zonal flows in toroidal plasmas". United States.
doi:10.1063/1.2435329.
@article{osti_20974832,
title = {Collisionless kineticfluid model of zonal flows in toroidal plasmas},
author = {Sugama, H. and Watanabe, T.H. and Horton, W. and Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712},
abstractNote = {A novel kineticfluid model is presented, which describes collisionless time evolution of zonal flows in tokamaks. In the new zonalflow closure relations, the parallel heat fluxes are written by the sum of short and longtimeevolution parts. The former part is given in the dissipative form of the parallel heat diffusion and relates to collisionless damping processes. The latter is derived from the longtimeaveraged gyrocenter distribution and plays a major role in describing lowfrequency or stationary zonal flows, for which the parallel heat fluxes are expressed in terms of the parallel flow as well as the nonlinearsource and initialcondition terms. It is shown analytically and numerically that, when applied to the zonal flow driven by either ion or electron temperature gradient turbulence, the kineticfluid equations including the new closure relations can reproduce the same longtime zonalflow responses to the initial condition and to the turbulence source as those obtained from the gyrokinetic model.},
doi = {10.1063/1.2435329},
journal = {Physics of Plasmas},
number = 2,
volume = 14,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}

Fluid simulation of linear zonal flow damping is done with a closure model based on the collisionless gyrokinetics [Sugama et al., Phys. Plasmas 14, 022502 (2007)]. Simulation results of residual zonal flow for low radial wavenumbers are compared with theoretical formulas for circular and noncircular tokamaks. The effects of the elongation and the triangularity are shown to be properly treated in the closure model. Effects of initial parallel flows on zonal flow evolution are also clarified. An appropriate choice of the initial parallel flow gives a much higher residual level than the conventional result with no initial parallel flow. Besides,more »

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