skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Gyrokinetic Simulation of Global Turbulent Transport Properties in Tokamak Experiments

Abstract

A general geometry gyro-kinetic model for particle simulation of plasma turbulence in tokamak experiments is described. It incorporates the comprehensive influence of noncircular cross section, realistic plasma profiles, plasma rotation, neoclassical (equilibrium) electric fields, and Coulomb collisions. An interesting result of global turbulence development in a shaped tokamak plasma is presented with regard to nonlinear turbulence spreading into the linearly stable region. The mutual interaction between turbulence and zonal flows in collisionless plasmas is studied with a focus on identifying possible nonlinear saturation mechanisms for zonal flows. A bursting temporal behavior with a period longer than the geodesic acoustic oscillation period is observed even in a collisionless system. Our simulation results suggest that the zonal flows can drive turbulence. However, this process is too weak to be an effective zonal flow saturation mechanism.

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
941506
Report Number(s):
PPPL-4142
Journal ID: ISSN 1070-664X; PHPAEN; TRN: US0807439
DOE Contract Number:
DE-AC02-76CH03073
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 13; Journal Issue: 9
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ACOUSTICS; COLLISIONLESS PLASMA; CROSS SECTIONS; ELECTRIC FIELDS; GEODESICS; GEOMETRY; OSCILLATIONS; PLASMA; ROTATION; SATURATION; SIMULATION; TRANSPORT; TURBULENCE; plasma turbulence, plasma transport processes, Tokamak devices, plasma toroidal confinement, plasma simulation, plasma flow, plasma collision processes, plasma nonlinear processes, plasma oscillations

Citation Formats

Wang, W.X., Lin, Z., Tang, W.M., Lee, W.W., Ethier, S., Lewandowski, J.L.V., Rewoldt, G., Hahm, T.S., and Manickam, J. Gyrokinetic Simulation of Global Turbulent Transport Properties in Tokamak Experiments. United States: N. p., 2006. Web. doi:10.1063/1.2338775.
Wang, W.X., Lin, Z., Tang, W.M., Lee, W.W., Ethier, S., Lewandowski, J.L.V., Rewoldt, G., Hahm, T.S., & Manickam, J. Gyrokinetic Simulation of Global Turbulent Transport Properties in Tokamak Experiments. United States. doi:10.1063/1.2338775.
Wang, W.X., Lin, Z., Tang, W.M., Lee, W.W., Ethier, S., Lewandowski, J.L.V., Rewoldt, G., Hahm, T.S., and Manickam, J. Sun . "Gyrokinetic Simulation of Global Turbulent Transport Properties in Tokamak Experiments". United States. doi:10.1063/1.2338775. https://www.osti.gov/servlets/purl/941506.
@article{osti_941506,
title = {Gyrokinetic Simulation of Global Turbulent Transport Properties in Tokamak Experiments},
author = {Wang, W.X. and Lin, Z. and Tang, W.M. and Lee, W.W. and Ethier, S. and Lewandowski, J.L.V. and Rewoldt, G. and Hahm, T.S. and Manickam, J.},
abstractNote = {A general geometry gyro-kinetic model for particle simulation of plasma turbulence in tokamak experiments is described. It incorporates the comprehensive influence of noncircular cross section, realistic plasma profiles, plasma rotation, neoclassical (equilibrium) electric fields, and Coulomb collisions. An interesting result of global turbulence development in a shaped tokamak plasma is presented with regard to nonlinear turbulence spreading into the linearly stable region. The mutual interaction between turbulence and zonal flows in collisionless plasmas is studied with a focus on identifying possible nonlinear saturation mechanisms for zonal flows. A bursting temporal behavior with a period longer than the geodesic acoustic oscillation period is observed even in a collisionless system. Our simulation results suggest that the zonal flows can drive turbulence. However, this process is too weak to be an effective zonal flow saturation mechanism.},
doi = {10.1063/1.2338775},
journal = {Physics of Plasmas},
number = 9,
volume = 13,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • A general geometry gyro-kinetic model for particle simulation of plasma turbulence in tokamak experiments is described. It incorporates the comprehensive influence of noncircular cross section, realistic plasma profiles, plasma rotation, neoclassical (equilibrium) electric fields, and Coulomb collisions. An interesting result of global turbulence development in a shaped tokamak plasma is presented with regard to nonlinear turbulence spreading into the linearly stable region. The mutual interaction between turbulence and zonal flows in collisionless plasmas is studied with a focus on identifying possible nonlinear saturation mechanisms for zonal flows. A bursting temporal behavior with a period longer than the geodesic acoustic oscillationmore » period is observed even in a collisionless system. Our simulation results suggest that the zonal flows can drive turbulence. However, this process is too weak to be an effective zonal flow saturation mechanism.« less
  • A kinetic simulation code based on the gyrokinetic ion dynamics in global general metric (including a tokamak with circular or noncircular cross-section) has been developed. This gyrokinetic simulation is capable of examining the global and semi-global driftwave structures and their associated transport in a tokamak plasma. We investigate the property of the ion temperature gradient (ITG) or {eta}{sub i}({eta}{sub i}{equivalent_to}{partial_derivative}&hthinsp;ln&hthinsp;T{sub i}/{partial_derivative}&hthinsp;ln&hthinsp;n{sub i}) driven drift waves in a tokamak plasma. The emergent semi-global drift wave modes give rise to thermal transport characterized by the Bohm scaling. {copyright} {ital 1999 American Institute of Physics.}
  • A new full f nonlinear gyrokinetic simulation code, named ELMFIRE, has been developed for simulating transport phenomena in tokamak plasmas. The code is based on a gyrokinetic particle-in-cell algorithm, which can consider electrons and ions jointly or separately, as well as arbitrary impurities. The implicit treatment of the ion polarization drift and the use of full f methods allow for simulations of strongly perturbed plasmas including wide orbit effects, steep gradients and rapid dynamic changes. This article presents in more detail the algorithms incorporated into ELMFIRE, as well as benchmarking comparisons to both neoclassical theory and other codes.Code ELMFIRE calculatesmore » plasma dynamics by following the evolution of a number of sample particles. Because of using an stochastic algorithm its results are influenced by statistical noise. The effect of noise on relevant magnitudes is analyzed.Turbulence spectra of FT-2 plasma has been calculated with ELMFIRE, obtaining results consistent with experimental data.« less
  • Electromagnetic gyrokinetic simulation in toroidal geometry is developed based on a fluid-kinetic hybrid electron model. The Alfven wave propagation in a fully global gyrokinetic particle simulation is investigated. In the long-wavelength magnetohydrodynamic limit, shear Alfven wave oscillations, continuum damping, and the appearance of the frequency gap in toroidal geometries are demonstrated. Wave propagation across the magnetic field (kinetic Alfven wave) is examined by comparing the simulation results with the theoretical dispersion relation. Furthermore, finite-beta stabilization of the ion temperature gradient mode and the onset of the kinetic ballooning mode are demonstrated.
  • The Eulerian gyrokinetic turbulence code gene has recently been extended to a full torus code. Moreover, it now provides Krook-type sources for gradient-driven simulations where the profiles are maintained on average as well as localized heat sources for a flux-driven type of operation. Careful verification studies and benchmarks are performed successfully. This setup is applied to address three related transport issues concerning nonlocal effects. First, it is confirmed that in gradient-driven simulations, the local limit can be reproduced--provided that finite aspect ratio effects in the geometry are treated carefully. In this context, it also becomes clear that the profile widthsmore » (not the device width) may constitute a more appropriate measure for finite-size effects. Second, the nature and role of heat flux avalanches are discussed in the framework of both local and global, flux- and gradient-driven simulations. Third, simulations dedicated to discharges with electron internal barriers are addressed.« less