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Title: Implementation and application of two synthetic diagnostics for validating simulations of core tokamak turbulence

Abstract

The deployment of multiple high-resolution, spatially localized fluctuation diagnostics on the DIII-D tokamak opens the door to a new level of core turbulence model validation. Toward this end, the implementation of synthetic diagnostics that model physical beam emission spectroscopy and correlation electron cyclotron emission diagnostics is presented. Initial results from their applications to local gyrokinetic simulations of two locations in a DIII-D L-mode discharge performed with the GYRO code are also discussed. At normalized toroidal flux ρ = 0.5, we find very good agreement between experiment and simulation in both the energy flows and fluctuation levels measured by both diagnostics. However, at ρ = 0.75, GYRO underpredicts the observed energy flows by roughly a factor of 7, with rms fluctuation levels underpredicted by a factor of 3. Interestingly, at both locations we find good agreement in the shapes of the radial and vertical density correlation functions and in the shapes of the frequency power spectra. Here, at both locations, the attenuation of the GYRO-predicted fluctuations due to the spatial averaging imposed by the diagnostics’ spot sizes is significant, and its incorporation via the use of synthetic diagnostics is shown to be essential for quantitative comparisons such as these.

Authors:
 [1];  [2];  [3];  [3];  [4];  [4];  [2];  [1]
  1. Univ. of California-San Diego, La Jolla, CA (United States)
  2. Univ. of California-Los Angeles, Los Angeles, CA (United States)
  3. Univ. of Wisconsin-Madison, Madison, WI (United States)
  4. General Atomics, San Diego, CA (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Univ. of California, Oakland, CA (United States); UT-Battelle LLC/ORNL, Oak Ridge, TN (United States); Univ. of California, San Diego, CA (United States); Univ. of Wisconsin, Madison, WI (United States); General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1564654
Grant/Contract Number:  
AC02-05CH11231; AC05-00OR22725; FG02-07ER54917; FG02-89ER53296; FG03-01ER54615; FG03-95ER54309
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 16; Journal Issue: 5; 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; Physics

Citation Formats

Holland, C., White, A. E., McKee, G. R., Shafer, M. W., Candy, J., Waltz, R. E., Schmitz, L., and Tynan, G. R. Implementation and application of two synthetic diagnostics for validating simulations of core tokamak turbulence. United States: N. p., 2009. Web. doi:10.1063/1.3085792.
Holland, C., White, A. E., McKee, G. R., Shafer, M. W., Candy, J., Waltz, R. E., Schmitz, L., & Tynan, G. R. Implementation and application of two synthetic diagnostics for validating simulations of core tokamak turbulence. United States. doi:10.1063/1.3085792.
Holland, C., White, A. E., McKee, G. R., Shafer, M. W., Candy, J., Waltz, R. E., Schmitz, L., and Tynan, G. R. Fri . "Implementation and application of two synthetic diagnostics for validating simulations of core tokamak turbulence". United States. doi:10.1063/1.3085792. https://www.osti.gov/servlets/purl/1564654.
@article{osti_1564654,
title = {Implementation and application of two synthetic diagnostics for validating simulations of core tokamak turbulence},
author = {Holland, C. and White, A. E. and McKee, G. R. and Shafer, M. W. and Candy, J. and Waltz, R. E. and Schmitz, L. and Tynan, G. R.},
abstractNote = {The deployment of multiple high-resolution, spatially localized fluctuation diagnostics on the DIII-D tokamak opens the door to a new level of core turbulence model validation. Toward this end, the implementation of synthetic diagnostics that model physical beam emission spectroscopy and correlation electron cyclotron emission diagnostics is presented. Initial results from their applications to local gyrokinetic simulations of two locations in a DIII-D L-mode discharge performed with the GYRO code are also discussed. At normalized toroidal flux ρ = 0.5, we find very good agreement between experiment and simulation in both the energy flows and fluctuation levels measured by both diagnostics. However, at ρ = 0.75, GYRO underpredicts the observed energy flows by roughly a factor of 7, with rms fluctuation levels underpredicted by a factor of 3. Interestingly, at both locations we find good agreement in the shapes of the radial and vertical density correlation functions and in the shapes of the frequency power spectra. Here, at both locations, the attenuation of the GYRO-predicted fluctuations due to the spatial averaging imposed by the diagnostics’ spot sizes is significant, and its incorporation via the use of synthetic diagnostics is shown to be essential for quantitative comparisons such as these.},
doi = {10.1063/1.3085792},
journal = {Physics of Plasmas},
number = 5,
volume = 16,
place = {United States},
year = {2009},
month = {5}
}

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