Nonlinear gyrokinetic simulations of the I-mode high confinement regime and comparisons with experimenta)
Name
Den Whyte White - Phys Plasmas 22 5 2015.pdf
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2.35 MB
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Author(s)
Holland, C.
Candy, J.
Theiler, C.
White, Anne E.
Howard, Nathaniel Thomas
Creely, Alexander James
Chilenski, Mark Alan
Hubbard, Amanda E
Hughes Jr, Jerry
Sierchio, Jennifer M.
Date Issued
May 2015
Journal
Physics of Plasmas
Publisher
American Institute of Physics (AIP)
Citation
White, A. E., N. T. Howard, A. J. Creely, M. A. Chilenski, M. Greenwald, A. E. Hubbard, J. W. Hughes, et al. “Nonlinear Gyrokinetic Simulations of the I-Mode High Confinement Regime and Comparisons with Experimenta).” Physics of Plasmas 22, no. 5 (May 2015):
Version
Final published version
Abstract
For the first time, nonlinear gyrokinetic simulations of I-mode plasmas are performed and compared with experiment. I-mode is a high confinement regime, featuring energy confinement similar to H-mode, but without enhanced particle and impurity particle confinement [D. G. Whyte et al., Nucl. Fusion 50, 105005 (2010)]. As a consequence of the separation between heat and particle transport, I-mode exhibits several favorable characteristics compared to H-mode. The nonlinear gyrokinetic code GYRO [J. Candy and R. E. Waltz, J Comput. Phys. 186, 545 (2003)] is used to explore the effects of E × B shear and profile stiffness in I-mode and compare with L-mode. The nonlinear GYRO simulations show that I-mode core ion temperature and electron temperature profiles are more stiff than L-mode core plasmas. Scans of the input E × B shear in GYRO simulations show that E × B shearing of turbulence is a stronger effect in the core of I-mode than L-mode. The nonlinear simulations match the observed reductions in long wavelength density fluctuation levels across the L-I transition but underestimate the reduction of long wavelength electron temperature fluctuation levels. The comparisons between experiment and gyrokinetic simulations for I-mode suggest that increased E × B shearing of turbulence combined with increased profile stiffness are responsible for the reductions in core turbulence observed in the experiment, and that I-mode resembles H-mode plasmas more than L-mode plasmas with regards to marginal stability and temperature profile stiffness.
MIT Department
Lincoln Laboratory
Massachusetts Institute of Technology. Department of Mathematics
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Plasma Science and Fusion Center
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DOI of Published Version
https://doi.org/10.1063/1.4921150
