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Title: Fluid simulations of turbulent impurity transport

Abstract

Impurity transport in tokamak plasmas is studied with a fluid turbulence code, which has been upgraded to implement two ion species and electrons. The (fixed-flux) simulations are compared to the predictions of a quasilinear model. These simulations mostly agree with quasilinear estimates; they indicate that a turbulent impurity pinch exists. Moreover, this pinch is found to be dominated by curvature terms, as thermodiffusion pinches are found to decrease as 1/Z and observed parallel velocity effects remain weak. The sign of the pinch is also investigated.

Authors:
; ; ; ;  [1]
  1. Association Euratom-CEA, CEA/DSM/DRFC, Centre de Cadarache, 13108 Saint-Paul-Lez-Durance (France)
Publication Date:
OSTI Identifier:
20974922
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 4; Other Information: DOI: 10.1063/1.2710461; (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; ELECTRONS; FORECASTING; IONS; PINCH EFFECT; PLASMA; PLASMA CONFINEMENT; PLASMA IMPURITIES; PLASMA SIMULATION; THERMAL DIFFUSION; TOKAMAK DEVICES; TURBULENCE

Citation Formats

Dubuit, N., Garbet, X., Parisot, T., Guirlet, R., and Bourdelle, C.. Fluid simulations of turbulent impurity transport. United States: N. p., 2007. Web. doi:10.1063/1.2710461.
Dubuit, N., Garbet, X., Parisot, T., Guirlet, R., & Bourdelle, C.. Fluid simulations of turbulent impurity transport. United States. doi:10.1063/1.2710461.
Dubuit, N., Garbet, X., Parisot, T., Guirlet, R., and Bourdelle, C.. Sun . "Fluid simulations of turbulent impurity transport". United States. doi:10.1063/1.2710461.
@article{osti_20974922,
title = {Fluid simulations of turbulent impurity transport},
author = {Dubuit, N. and Garbet, X. and Parisot, T. and Guirlet, R. and Bourdelle, C.},
abstractNote = {Impurity transport in tokamak plasmas is studied with a fluid turbulence code, which has been upgraded to implement two ion species and electrons. The (fixed-flux) simulations are compared to the predictions of a quasilinear model. These simulations mostly agree with quasilinear estimates; they indicate that a turbulent impurity pinch exists. Moreover, this pinch is found to be dominated by curvature terms, as thermodiffusion pinches are found to decrease as 1/Z and observed parallel velocity effects remain weak. The sign of the pinch is also investigated.},
doi = {10.1063/1.2710461},
journal = {Physics of Plasmas},
number = 4,
volume = 14,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}
  • Impurity transport is an important topic for ITER as impurity density in the core has to stay below a relative concentration of 5x10{sup -5} [1] to reach ignition conditions. The reasons for that is mainly impurity radiation leading to cooling. In the edge region on the other hand site, higher impurity densities, going along with radiation energy losses are beneficial as the radiative cooling arranges for good power distribution onto the first wall.
  • No abstract prepared.
  • The statistical properties of impurity transport of a tokamak edge plasma embedded in a dissipative drift-wave turbulence are investigated using structure function analysis. The impurities are considered as a passive scalar advected by the plasma flow. Two cases of impurity advection are studied and compared: A decaying impurities case (given by a diffusion-advection equation) and a driven case (forced by a mean scalar gradient). The use of extended self-similarity enables us to show that the relative scaling exponent of structure functions of impurity density and vorticity exhibit similar multifractal scaling in the decaying case and follows the She-Leveque model. However,more » this property is invalidated for the impurity driven advection case. For both cases, potential fluctuations are self-similar and exhibit a monofractal scaling in agreement with Kolmogorov-Kraichnan theory for two-dimensional turbulence. These results obtained with a passive scalar model agree also with test-particle simulations.« less
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