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Title: Synergistic cross-scale coupling of turbulence in a tokamak plasma

Abstract

For the first time, nonlinear gyrokinetic simulations spanning both the ion and electron spatio-temporal scales have been performed with realistic electron mass ratio ((mD/me)1/2 = 60.0), realistic geometry, and all experimental inputs, demonstrating the coexistence and synergy of ion ( ( k θ ρ s O ( 1.0 ) ) ) and electron-scale ( ( k θ ρ e O ( 1.0 ) ) ) turbulence in the core of a tokamak plasma. All multi-scale simulations utilized the GYRO code [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] to study the coupling of ion and electron-scale turbulence in the core (r/a = 0.6) of an Alcator C-Mod L-mode discharge shown previously to exhibit an under-prediction of the electron heat flux when using simulations only including ion-scale turbulence. Electron-scale turbulence is found to play a dominant role in setting the electron heat flux level and radially elongated (kr ≪ kθ) “streamers” are found to coexist with ion-scale eddies in experimental plasma conditions. Inclusion of electron-scale turbulence in these simulations is found to increase both ion and electron heat flux levels by enhancing the transport at the ion-scale while also driving electron heat flux at sub-ρi scales. The combined increases in the low and high-k driven electron heat flux may explain previously observed discrepancies between simulated and experimental electron heat fluxes and indicates a complex interaction of short and long wavelength turbulence.

Authors:
 [1];  [2];  [3];  [3];  [4]
  1. Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States)
  2. Univ. of California, San Diego, CA (United States)
  3. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
  4. General Atomics, San Diego, CA (United States)
Publication Date:
Research Org.:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1546776
Alternate Identifier(s):
OSTI ID: 1224317
Grant/Contract Number:  
FC02-99ER54512; AC02-05CH11231; FC02-99ER54512-CMOD
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 21; Journal Issue: 11; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Howard, N. T., Holland, C., White, A. E., Greenwald, M., and Candy, J.. Synergistic cross-scale coupling of turbulence in a tokamak plasma. United States: N. p., 2014. Web. https://doi.org/10.1063/1.4902366.
Howard, N. T., Holland, C., White, A. E., Greenwald, M., & Candy, J.. Synergistic cross-scale coupling of turbulence in a tokamak plasma. United States. https://doi.org/10.1063/1.4902366
Howard, N. T., Holland, C., White, A. E., Greenwald, M., and Candy, J.. Mon . "Synergistic cross-scale coupling of turbulence in a tokamak plasma". United States. https://doi.org/10.1063/1.4902366. https://www.osti.gov/servlets/purl/1546776.
@article{osti_1546776,
title = {Synergistic cross-scale coupling of turbulence in a tokamak plasma},
author = {Howard, N. T. and Holland, C. and White, A. E. and Greenwald, M. and Candy, J.},
abstractNote = {For the first time, nonlinear gyrokinetic simulations spanning both the ion and electron spatio-temporal scales have been performed with realistic electron mass ratio ((mD/me)1/2 = 60.0), realistic geometry, and all experimental inputs, demonstrating the coexistence and synergy of ion ( ( k θ ρ s ∼ O ( 1.0 ) ) ) and electron-scale ( ( k θ ρ e ∼ O ( 1.0 ) ) ) turbulence in the core of a tokamak plasma. All multi-scale simulations utilized the GYRO code [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] to study the coupling of ion and electron-scale turbulence in the core (r/a = 0.6) of an Alcator C-Mod L-mode discharge shown previously to exhibit an under-prediction of the electron heat flux when using simulations only including ion-scale turbulence. Electron-scale turbulence is found to play a dominant role in setting the electron heat flux level and radially elongated (kr ≪ kθ) “streamers” are found to coexist with ion-scale eddies in experimental plasma conditions. Inclusion of electron-scale turbulence in these simulations is found to increase both ion and electron heat flux levels by enhancing the transport at the ion-scale while also driving electron heat flux at sub-ρi scales. The combined increases in the low and high-k driven electron heat flux may explain previously observed discrepancies between simulated and experimental electron heat fluxes and indicates a complex interaction of short and long wavelength turbulence.},
doi = {10.1063/1.4902366},
journal = {Physics of Plasmas},
number = 11,
volume = 21,
place = {United States},
year = {2014},
month = {11}
}

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