Nonlinear gyrokinetic simulations of the I-mode high confinement regime and comparisons with experimenta)
Name
Anne White White - Phys of Plasmas 22 5 2015 - Authors Manuscript .pdf
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Author(s)
Mikkelsen, D. R.
Edlund, E. M.
Kung, C.
Holland, C.
Candy, J.
Petty, C. C.
Reinke, M. L.
Theiler, C.
White, Anne E.
Howard, Nathaniel Thomas
Date Issued
May 2015
Journal
Physics of Plasmas
Publisher
American Institute of Physics (AIP)
Citation
White, A. E.; Howard, N. T.; Creely, A. J.; Chilenski, M. A.; Greenwald, M.; Hubbard, A. E.; Hughes, J. W., et al. “Nonlinear Gyrokinetic Simulations of the I-Mode High Confinement Regime and Comparisons with Experimenta).” Physics of Plasmas 22, no. 5 (May 2015): 056109. © 2015 American Institute of Physics (AIP)
Version
Author's final manuscript
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
Massachusetts Institute of Technology. Plasma Science and Fusion Center
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DOI of Published Version
https://doi.org/10.1063/1.4921150
