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Title: Characterizing electron temperature gradient turbulence via numerical simulation

Abstract

Numerical simulations of electron temperature gradient (ETG) turbulence are presented that characterize the ETG fluctuation spectrum, establish limits to the validity of the adiabatic ion model often employed in studying ETG turbulence, and support the tentative conclusion that plasma-operating regimes exist in which ETG turbulence produces sufficient electron heat transport to be experimentally relevant. We resolve prior controversies regarding simulation techniques and convergence by benchmarking simulations of ETG turbulence from four microturbulence codes, demonstrating agreement on the electron heat flux, correlation functions, fluctuation intensity, and rms flow shear at fixed simulation cross section and resolution in the plane perpendicular to the magnetic field. Excellent convergence of both continuum and particle-in-cell codes with time step and velocity-space resolution is demonstrated, while numerical issues relating to perpendicular (to the magnetic field) simulation dimensions and resolution are discussed. A parameter scan in the magnetic shear, s, demonstrates that the adiabatic ion model is valid at small values of s (s<0.4 for the parameters used in this scan) but breaks down at higher magnetic shear. A proper treatment employing gyrokinetic ions reveals a steady increase in the electron heat transport with increasing magnetic shear, reaching electron heat transport rates consistent with analyses of experimentalmore » tokamak discharges.« less

Authors:
; ; ; ; ; ; ; ; ; ;  [1];  [2];  [2];  [3];  [2];  [2];  [2];  [2];  [4];  [2]
  1. Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)
  2. (United States)
  3. (CRPP), Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)
  4. (Germany)
Publication Date:
OSTI Identifier:
20860430
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 13; Journal Issue: 12; Other Information: DOI: 10.1063/1.2402510; (c) 2006 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; CONVERGENCE; CORRELATION FUNCTIONS; ELECTRON TEMPERATURE; ELECTRONS; FLUCTUATIONS; HEAT FLUX; HEAT TRANSFER; ION TEMPERATURE; IONS; MAGNETIC FIELDS; NUMERICAL ANALYSIS; PLASMA; PLASMA CONFINEMENT; PLASMA SIMULATION; RADIATION TRANSPORT; SHEAR; TEMPERATURE GRADIENTS; TOKAMAK DEVICES; TURBULENCE

Citation Formats

Nevins, W. M., Candy, J., Cowley, S., Dannert, T., Dimits, A., Dorland, W., Estrada-Mila, C., Hammett, G. W., Jenko, F., Pueschel, M. J., Shumaker, D. E., General Atomics, San Diego, California 92186, Department of Physics and Astronomy, UCLA, Los Angeles, California 90095-1547, Centre de Recherches en Physique des Plasmas, Lawrence Livermore National Laboratory, Livermore, California 94551, University of Maryland, College Park, Maryland 20742, Department of Mechanical and Aerospace Engineering, UCSD, San Diego, California 92093, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08536, Max-Planck Institut fuer Plasmaphysik, D-85748 Garching, and Lawrence Livermore National Laboratory, Livermore, California 94551. Characterizing electron temperature gradient turbulence via numerical simulation. United States: N. p., 2006. Web. doi:10.1063/1.2402510.
Nevins, W. M., Candy, J., Cowley, S., Dannert, T., Dimits, A., Dorland, W., Estrada-Mila, C., Hammett, G. W., Jenko, F., Pueschel, M. J., Shumaker, D. E., General Atomics, San Diego, California 92186, Department of Physics and Astronomy, UCLA, Los Angeles, California 90095-1547, Centre de Recherches en Physique des Plasmas, Lawrence Livermore National Laboratory, Livermore, California 94551, University of Maryland, College Park, Maryland 20742, Department of Mechanical and Aerospace Engineering, UCSD, San Diego, California 92093, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08536, Max-Planck Institut fuer Plasmaphysik, D-85748 Garching, & Lawrence Livermore National Laboratory, Livermore, California 94551. Characterizing electron temperature gradient turbulence via numerical simulation. United States. doi:10.1063/1.2402510.
Nevins, W. M., Candy, J., Cowley, S., Dannert, T., Dimits, A., Dorland, W., Estrada-Mila, C., Hammett, G. W., Jenko, F., Pueschel, M. J., Shumaker, D. E., General Atomics, San Diego, California 92186, Department of Physics and Astronomy, UCLA, Los Angeles, California 90095-1547, Centre de Recherches en Physique des Plasmas, Lawrence Livermore National Laboratory, Livermore, California 94551, University of Maryland, College Park, Maryland 20742, Department of Mechanical and Aerospace Engineering, UCSD, San Diego, California 92093, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08536, Max-Planck Institut fuer Plasmaphysik, D-85748 Garching, and Lawrence Livermore National Laboratory, Livermore, California 94551. Fri . "Characterizing electron temperature gradient turbulence via numerical simulation". United States. doi:10.1063/1.2402510.
@article{osti_20860430,
title = {Characterizing electron temperature gradient turbulence via numerical simulation},
author = {Nevins, W. M. and Candy, J. and Cowley, S. and Dannert, T. and Dimits, A. and Dorland, W. and Estrada-Mila, C. and Hammett, G. W. and Jenko, F. and Pueschel, M. J. and Shumaker, D. E. and General Atomics, San Diego, California 92186 and Department of Physics and Astronomy, UCLA, Los Angeles, California 90095-1547 and Centre de Recherches en Physique des Plasmas and Lawrence Livermore National Laboratory, Livermore, California 94551 and University of Maryland, College Park, Maryland 20742 and Department of Mechanical and Aerospace Engineering, UCSD, San Diego, California 92093 and Princeton Plasma Physics Laboratory, Princeton, New Jersey 08536 and Max-Planck Institut fuer Plasmaphysik, D-85748 Garching and Lawrence Livermore National Laboratory, Livermore, California 94551},
abstractNote = {Numerical simulations of electron temperature gradient (ETG) turbulence are presented that characterize the ETG fluctuation spectrum, establish limits to the validity of the adiabatic ion model often employed in studying ETG turbulence, and support the tentative conclusion that plasma-operating regimes exist in which ETG turbulence produces sufficient electron heat transport to be experimentally relevant. We resolve prior controversies regarding simulation techniques and convergence by benchmarking simulations of ETG turbulence from four microturbulence codes, demonstrating agreement on the electron heat flux, correlation functions, fluctuation intensity, and rms flow shear at fixed simulation cross section and resolution in the plane perpendicular to the magnetic field. Excellent convergence of both continuum and particle-in-cell codes with time step and velocity-space resolution is demonstrated, while numerical issues relating to perpendicular (to the magnetic field) simulation dimensions and resolution are discussed. A parameter scan in the magnetic shear, s, demonstrates that the adiabatic ion model is valid at small values of s (s<0.4 for the parameters used in this scan) but breaks down at higher magnetic shear. A proper treatment employing gyrokinetic ions reveals a steady increase in the electron heat transport with increasing magnetic shear, reaching electron heat transport rates consistent with analyses of experimental tokamak discharges.},
doi = {10.1063/1.2402510},
journal = {Physics of Plasmas},
number = 12,
volume = 13,
place = {United States},
year = {Fri Dec 15 00:00:00 EST 2006},
month = {Fri Dec 15 00:00:00 EST 2006}
}