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Title: Impurity-induced turbulence suppression and reduced transport in the DIII-D tokamak

Abstract

Long wavelength turbulence as well as heat and momentum transport are significantly reduced in the DIII-D tokamak [Plasma Physics and Controlled Nuclear Fusion Research (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159] as a result of neon seeding of a low confinement mode negative central shear discharge. Correspondingly, the energy confinement time increases by up to 80%. Fully saturated turbulence measurements near {rho}=0.7 ({rho}=r/a) in the wave number range 0.1{<=}k{sub (perpendicular} {sub sign)}{rho}{sub s}{<=}0.6, obtained with beam emission spectroscopy, exhibit a significant reduction of fluctuation power after neon injection. Fluctuation measurements obtained with far infrared scattering also show a reduction of turbulence in the core, while the Langmuir probe array measures reduced particle flux in the edge and scrape-off layer. Gyrokinetic linear stability simulations of these plasmas are qualitatively consistent, showing a reduction in the growth rate of ion temperature gradient driven modes for 0<k{sub (perpendicular} {sub sign)}{rho}{sub s}{<=}1.4, and nonlinear gyrokinetic simulations show a reduced saturated density fluctuation amplitude. The measured {omega}{sub ExB} shearing rate increased at {rho}=0.7, suggesting that impurity-induced growth rate reduction is acting synergistically with {omega}{sub ExB} shear to decrease turbulence and reduce anomalous transport. (c) 2000 American Institute of Physics.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [2]
  1. General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)
  2. General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States) (and others)
Publication Date:
OSTI Identifier:
20216055
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 7; Journal Issue: 5; Other Information: PBD: May 2000; Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; PLASMA IMPURITIES; TOKAMAK DEVICES; TURBULENCE; PLASMA DIAGNOSTICS; CHARGED-PARTICLE TRANSPORT; EXPERIMENTAL DATA; THEORETICAL DATA

Citation Formats

McKee, G. R., Murakami, M., Boedo, J. A., Brooks, N. H., Burrell, K. H., Ernst, D. R., Fonck, R. J., Jackson, G. L., Jakubowski, M., and La Haye, R. J. Impurity-induced turbulence suppression and reduced transport in the DIII-D tokamak. United States: N. p., 2000. Web. doi:10.1063/1.874010.
McKee, G. R., Murakami, M., Boedo, J. A., Brooks, N. H., Burrell, K. H., Ernst, D. R., Fonck, R. J., Jackson, G. L., Jakubowski, M., & La Haye, R. J. Impurity-induced turbulence suppression and reduced transport in the DIII-D tokamak. United States. doi:10.1063/1.874010.
McKee, G. R., Murakami, M., Boedo, J. A., Brooks, N. H., Burrell, K. H., Ernst, D. R., Fonck, R. J., Jackson, G. L., Jakubowski, M., and La Haye, R. J. Mon . "Impurity-induced turbulence suppression and reduced transport in the DIII-D tokamak". United States. doi:10.1063/1.874010.
@article{osti_20216055,
title = {Impurity-induced turbulence suppression and reduced transport in the DIII-D tokamak},
author = {McKee, G. R. and Murakami, M. and Boedo, J. A. and Brooks, N. H. and Burrell, K. H. and Ernst, D. R. and Fonck, R. J. and Jackson, G. L. and Jakubowski, M. and La Haye, R. J.},
abstractNote = {Long wavelength turbulence as well as heat and momentum transport are significantly reduced in the DIII-D tokamak [Plasma Physics and Controlled Nuclear Fusion Research (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159] as a result of neon seeding of a low confinement mode negative central shear discharge. Correspondingly, the energy confinement time increases by up to 80%. Fully saturated turbulence measurements near {rho}=0.7 ({rho}=r/a) in the wave number range 0.1{<=}k{sub (perpendicular} {sub sign)}{rho}{sub s}{<=}0.6, obtained with beam emission spectroscopy, exhibit a significant reduction of fluctuation power after neon injection. Fluctuation measurements obtained with far infrared scattering also show a reduction of turbulence in the core, while the Langmuir probe array measures reduced particle flux in the edge and scrape-off layer. Gyrokinetic linear stability simulations of these plasmas are qualitatively consistent, showing a reduction in the growth rate of ion temperature gradient driven modes for 0<k{sub (perpendicular} {sub sign)}{rho}{sub s}{<=}1.4, and nonlinear gyrokinetic simulations show a reduced saturated density fluctuation amplitude. The measured {omega}{sub ExB} shearing rate increased at {rho}=0.7, suggesting that impurity-induced growth rate reduction is acting synergistically with {omega}{sub ExB} shear to decrease turbulence and reduce anomalous transport. (c) 2000 American Institute of Physics.},
doi = {10.1063/1.874010},
journal = {Physics of Plasmas},
issn = {1070-664X},
number = 5,
volume = 7,
place = {United States},
year = {2000},
month = {5}
}