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Title: Nonlinear gyrokinetic simulations of the I-mode high confinement regime and comparisons with experiment

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 combinedmore » 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.« less
Authors:
; ; ; ; ; ; ; ; ; ; ; ;  [1] ; ; ;  [2] ;  [3] ; ;  [4] ;  [5] more »; « less
  1. MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States)
  2. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States)
  3. University of California, San Diego (UCSD) San Diego, California 92093 (United States)
  4. General Atomics, P.O. Box 85608, San Diego, California 92186 (United States)
  5. York University, Heslington, York YO10 5DD (United Kingdom)
Publication Date:
OSTI Identifier:
22410389
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 5; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; COMPARATIVE EVALUATIONS; ELECTRIC FIELDS; ELECTRON TEMPERATURE; FLEXIBILITY; FLUCTUATIONS; H-MODE PLASMA CONFINEMENT; ION TEMPERATURE; L-MODE PLASMA CONFINEMENT; MAGNETIC FIELDS; NONLINEAR PROBLEMS; PLASMA IMPURITIES; PLASMA SIMULATION; SHEAR; TURBULENCE; WAVELENGTHS