Advances in validating gyrokinetic turbulence models against L- and H-mode plasmas

C. Holland; L. Schmitz; T. L. Rhodes; W. A. Peebles; J. C. Hillesheim; G. Wang; L. Zeng; E. J. Doyle; S. P. Smith; R. Prater; K. H. Burrell; J. Candy; R. E. Waltz; J. E. Kinsey; G. M. Staebler; J. C. Deboo; C. C. Petty; G. R. McKee; Z. Yan; A. E. White

doi:10.1063/1.3574518

Advances in validating gyrokinetic turbulence models against L- and H-mode plasmas

C. Holland, L. Schmitz, T. L. Rhodes, W. A. Peebles, J. C. Hillesheim, G. Wang, L. Zeng, E. J. Doyle, S. P. Smith, R. Prater, K. H. Burrell, J. Candy, R. E. Waltz, J. E. Kinsey, G. M. Staebler, J. C. Deboo, C. C. Petty, G. R. McKee, Z. Yan, A. E. White

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Abstract

Robust validation of predictive turbulent transport models requires quantitative comparisons to experimental measurements at multiple levels, over a range of physically relevant conditions. Toward this end, a series of carefully designed validation experiments has been performed on the DIII-D tokamak J. L. Luxon, Nucl. Fusion 42, 614 (2002) to obtain comprehensive multifield, multipoint, multiwavenumber fluctuation measurements and their scalings with key dimensionless parameters. The results of two representative validation studies are presented: an elongation scaling study performed in beam heated L-mode discharges and an electron heating power scan performed in quiescent H-mode (QH-mode) discharges. A 50% increase in the elongation κ is observed to lead to a ∼50 increase in energy confinement time τe and accompanying decrease in fluctuation levels, qualitatively consistent with a priori theoretical predictions and nonlinear GYRO J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003) simulations. However, these simulations exhibit clear quantitative differences from experiment in the predicted magnitudes and trends with radius of turbulent fluxes and fluctuation levels which cannot be fully accounted for by uncertainties due to transport stiffness. In the QH-mode study, local nonlinear GYRO simulations that neglect fast ion effects show a similar proportional response to the applied electron cyclotron heating as the experiment, but overpredict the magnitudes of transport and fluctuation levels by a factor of 10 or more. Possible sources of this overprediction, namely nonlocal effects and self-consistent fast beam ions, are identified and discussed.

Original language	English
Article number	056113
Journal	Physics of Plasmas
Volume	18
Issue number	5
DOIs	https://doi.org/10.1063/1.3574518
State	Published - May 2011
Externally published	Yes

Funding

This work was supported by the US Department of Energy under DE-FG02-07ER54917, DE-FG02-06ER54871, DE-FG02-08ER54984, DE-FC02-04ER54309, DE-FG02-95ER54309, DE-FG02-89ER53296, DE-FG02-08ER54999, and DE-FC02-99E4512. This research was performed in collaboration with the Center for Simulations of Plasma Microturbulence and used resources of the National Center for Computational Sciences at Oak Ridge National Laboratory, which is supported by the Office of Science of the Department of Energy under Contract No. DE-AC05-00OR22725. The authors would like to thank G. R. Tynan, D. R. Ernst, D. R. Mikkelsen, W. M. Nevins, G. W. Hammett, and P. B. Snyder for many useful discussions.

Funders	Funder number
Office of Science of the Department of Energy	DE-AC05-00OR22725
U.S. Department of Energy	DE-FG02-06ER54871, DE-FG02-08ER54999, DE-FG02-08ER54984, DE-FG02-07ER54917, DE-FC02-99E4512, DE-FG02-89ER53296, DE-FC02-04ER54309, DE-FG02-95ER54309

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This output contributes to the following UN Sustainable Development Goals (SDGs)

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Holland, C., Schmitz, L., Rhodes, T. L., Peebles, W. A., Hillesheim, J. C., Wang, G., Zeng, L., Doyle, E. J., Smith, S. P., Prater, R., Burrell, K. H., Candy, J., Waltz, R. E., Kinsey, J. E., Staebler, G. M., Deboo, J. C., Petty, C. C., McKee, G. R., Yan, Z., & White, A. E. (2011). Advances in validating gyrokinetic turbulence models against L- and H-mode plasmas. Physics of Plasmas, 18(5), Article 056113. https://doi.org/10.1063/1.3574518

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title = "Advances in validating gyrokinetic turbulence models against L- and H-mode plasmas",

abstract = "Robust validation of predictive turbulent transport models requires quantitative comparisons to experimental measurements at multiple levels, over a range of physically relevant conditions. Toward this end, a series of carefully designed validation experiments has been performed on the DIII-D tokamak J. L. Luxon, Nucl. Fusion 42, 614 (2002) to obtain comprehensive multifield, multipoint, multiwavenumber fluctuation measurements and their scalings with key dimensionless parameters. The results of two representative validation studies are presented: an elongation scaling study performed in beam heated L-mode discharges and an electron heating power scan performed in quiescent H-mode (QH-mode) discharges. A 50% increase in the elongation κ is observed to lead to a ∼50 increase in energy confinement time τe and accompanying decrease in fluctuation levels, qualitatively consistent with a priori theoretical predictions and nonlinear GYRO J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003) simulations. However, these simulations exhibit clear quantitative differences from experiment in the predicted magnitudes and trends with radius of turbulent fluxes and fluctuation levels which cannot be fully accounted for by uncertainties due to transport stiffness. In the QH-mode study, local nonlinear GYRO simulations that neglect fast ion effects show a similar proportional response to the applied electron cyclotron heating as the experiment, but overpredict the magnitudes of transport and fluctuation levels by a factor of 10 or more. Possible sources of this overprediction, namely nonlocal effects and self-consistent fast beam ions, are identified and discussed.",

author = "C. Holland and L. Schmitz and Rhodes, {T. L.} and Peebles, {W. A.} and Hillesheim, {J. C.} and G. Wang and L. Zeng and Doyle, {E. J.} and Smith, {S. P.} and R. Prater and Burrell, {K. H.} and J. Candy and Waltz, {R. E.} and Kinsey, {J. E.} and Staebler, {G. M.} and Deboo, {J. C.} and Petty, {C. C.} and McKee, {G. R.} and Z. Yan and White, {A. E.}",

year = "2011",

month = may,

doi = "10.1063/1.3574518",

language = "English",

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Holland, C, Schmitz, L, Rhodes, TL, Peebles, WA, Hillesheim, JC, Wang, G, Zeng, L, Doyle, EJ, Smith, SP, Prater, R, Burrell, KH, Candy, J, Waltz, RE, Kinsey, JE, Staebler, GM, Deboo, JC, Petty, CC, McKee, GR, Yan, Z & White, AE 2011, 'Advances in validating gyrokinetic turbulence models against L- and H-mode plasmas', Physics of Plasmas, vol. 18, no. 5, 056113. https://doi.org/10.1063/1.3574518

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AU - Holland, C.

AU - Schmitz, L.

AU - Rhodes, T. L.

AU - Peebles, W. A.

AU - Hillesheim, J. C.

AU - Wang, G.

AU - Zeng, L.

AU - Doyle, E. J.

AU - Smith, S. P.

AU - Prater, R.

AU - Burrell, K. H.

AU - Candy, J.

AU - Waltz, R. E.

AU - Kinsey, J. E.

AU - Staebler, G. M.

AU - Deboo, J. C.

AU - Petty, C. C.

AU - McKee, G. R.

AU - Yan, Z.

AU - White, A. E.

PY - 2011/5

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AB - Robust validation of predictive turbulent transport models requires quantitative comparisons to experimental measurements at multiple levels, over a range of physically relevant conditions. Toward this end, a series of carefully designed validation experiments has been performed on the DIII-D tokamak J. L. Luxon, Nucl. Fusion 42, 614 (2002) to obtain comprehensive multifield, multipoint, multiwavenumber fluctuation measurements and their scalings with key dimensionless parameters. The results of two representative validation studies are presented: an elongation scaling study performed in beam heated L-mode discharges and an electron heating power scan performed in quiescent H-mode (QH-mode) discharges. A 50% increase in the elongation κ is observed to lead to a ∼50 increase in energy confinement time τe and accompanying decrease in fluctuation levels, qualitatively consistent with a priori theoretical predictions and nonlinear GYRO J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003) simulations. However, these simulations exhibit clear quantitative differences from experiment in the predicted magnitudes and trends with radius of turbulent fluxes and fluctuation levels which cannot be fully accounted for by uncertainties due to transport stiffness. In the QH-mode study, local nonlinear GYRO simulations that neglect fast ion effects show a similar proportional response to the applied electron cyclotron heating as the experiment, but overpredict the magnitudes of transport and fluctuation levels by a factor of 10 or more. Possible sources of this overprediction, namely nonlocal effects and self-consistent fast beam ions, are identified and discussed.

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Advances in validating gyrokinetic turbulence models against L- and H-mode plasmas

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