Multi-scale gyrokinetic simulations: Comparison with experiment and implications for predicting turbulence and transport
Name
Anne White Howard - Phys of Plasmas 23 5 2016.pdf
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2.18 MB
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Author(s)
Holland, C.
Candy, J.
Howard, Nathaniel Thomas
White, Anne E.
Creely, Alexander James
Greenwald, Martin J.
Date Issued
April 2016
Journal
Physics of Plasmas
Publisher
American Institute of Physics (AIP)
Citation
Howard, N. T.; Holland, C.; White, A. E.; Greenwald, M.; Candy, J. and Creely, A. J. “Multi-Scale Gyrokinetic Simulations: Comparison with Experiment and Implications for Predicting Turbulence and Transport.” Physics of Plasmas 23, no. 5 (May 2016): 056109. © 2016 American Institute of Physics (AIP)
Version
Final published version
Abstract
To better understand the role of cross-scale coupling in experimental conditions, a series of multi-scale gyrokinetic simulations were performed on Alcator C-Mod, L-mode plasmas. These simulations, performed using all experimental inputs and realistic ion to electron mass ratio ((mi/me)1∕2 = 60.0), simultaneously capture turbulence at the ion (kθρs∼𝒪(1.0)) and electron-scales (kθρe∼𝒪(1.0)). Direct comparison with experimental heat fluxes and electron profile stiffness indicates that Electron Temperature Gradient (ETG) streamers and strong cross-scale turbulence coupling likely exist in both of the experimental conditions studied. The coupling between ion and electron-scales exists in the form of energy cascades, modification of zonal flow dynamics, and the effective shearing of ETG turbulence by long wavelength, Ion Temperature Gradient (ITG) turbulence. The tightly coupled nature of ITG and ETG turbulence in these realistic plasma conditions is shown to have significant implications for the interpretation of experimental transport and fluctuations. Initial attempts are made to develop a “rule of thumb” based on linear physics, to help predict when cross-scale coupling plays an important role and to inform future modeling of experimental discharges. The details of the simulations, comparisons with experimental measurements, and implications for both modeling and experimental interpretation are discussed.
MIT Department
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
Massachusetts Institute of Technology. Plasma Science and Fusion Center
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DOI of Published Version
https://doi.org/10.1063/1.4946028
