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Title: Electron temperature critical gradient and transport stiffness in DIII-D

Journal Article · · Nuclear Fusion
 [1];  [1];  [2];  [3];  [4];  [5];  [6];  [1]
  1. General Atomics, San Diego, CA (United States)
  2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  3. Univ. of California, San Diego, CA (United States)
  4. Fourth State Research, Austin, TX (United States)
  5. Univ. of Texas, Austin, TX (United States)
  6. Univ. of California, Los Angeles, CA (United States)

The electron energy flux has been probed as a function of electron temperature gradient on the DIII-D tokamak, in a continuing effort to validate turbulent transport models. In the scan of gradient, a critical electron temperature gradient has been found in the electron heat fluxes and stiffness at various radii in L-mode plasmas. The TGLF reduced turbulent transport model [G.M. Staebler et al, Phys. Plasmas 14, 055909 (2007)] and full gyrokinetic GYRO model [J. Candy and R.E. Waltz, J. Comput. Phys. 186, 545 (2003)] recover the general trend of increasing electron energy flux with increasing electron temperature gradient scale length, but they do not predict the absolute level of transport at all radii and gradients. Comparing the experimental observations of incremental (heat pulse) diffusivity and stiffness to the models’ reveals that TGLF reproduces the trends in increasing diffusivity and stiffness with increasing electron temperature gradient scale length with a critical gradient behavior. Furthermore, the critical gradient of TGLF is found to have a dependence on q95, contrary to the independence of the experimental critical gradient from q95.

Research Organization:
General Atomics, San Diego, CA (United States)
Sponsoring Organization:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
Grant/Contract Number:
FC02-04ER54698; FC02-99ER54512; FG02-08ER54871; FG02-08ER54984; FG03-97ER54415
OSTI ID:
1345509
Alternate ID(s):
OSTI ID: 1238892
Journal Information:
Nuclear Fusion, Vol. 55, Issue 8; ISSN 0029-5515
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 17 works
Citation information provided by
Web of Science

References (19)

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A Key to Improved Ion Core Confinement in the JET Tokamak: Ion Stiffness Mitigation due to Combined Plasma Rotation and Low Magnetic Shear journal September 2011
Electron profile stiffness and critical gradient studies journal August 2012
Discriminating the role of rotation and its gradient in determining ion stiffness mitigation in JET journal January 2013
Observation of a Critical Gradient Threshold for Electron Temperature Fluctuations in the DIII-D Tokamak journal January 2013
Validation studies of gyrofluid and gyrokinetic predictions of transport and turbulence stiffness using the DIII-D tokamak journal July 2013
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Cited By (6)

Validation metrics for turbulent plasma transport journal June 2016
Progress and challenges in understanding core transport in tokamaks in support to ITER operations journal December 2019
Impact of electron-scale turbulence and multi-scale interactions in the JET tokamak journal September 2018
Evaluating the effects of tungsten on CFETR phase I performance journal October 2018
Initial transport and turbulence analysis and gyrokinetic simulation validation in NSTX-U L-mode plasmas journal April 2019
Investigation of the role of electron temperature gradient modes in electron heat transport in TCV plasmas journal October 2019

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