Nonlinear gyrokinetic simulations of the I-mode high confinement regime and comparisons with experimenta)

White, Anne; Howard, N. T.; Creely, A. J.; Chilenski, Mark; Greenwald, M.; Hubbard, A.; Hughes, J. W.; Marmar, E.; Rice, J. E.; Sierchio, J. M.; Sung, C.; Walk, J.; Whyte, D.G.; Mikkelsen, D. R.; Edlund, E.; Kung, C. C.; Holland, C.; Candy, J.; Petty, C. C.; Reinke, M.L.; Theiler, C.

doi:10.1063/1.4921150

Cited by 18 publications

(24 citation statements)

References 44 publications

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“…This method is consistent with the past validation studies of gyrokinetic codes on Alcator C-Mod, where ITG is typically dominant in most L-, I-, and H-mode plasmas. 11,12,15,38,39 Once the ion heat flux-matched simulations were obtained, scans of a=L Te enabled the measurement of the perturbative thermal diffusivity, calculated with Equation (8).…”

Section: Comparison To Nonlinear Gyro Resultsmentioning

confidence: 99%

“…v PB e depends inversely on density and H-mode tends to have a strong density increase while I-mode does not. 12 …”

Section: -3mentioning

confidence: 99%

“…This decrease in turbulence at all radii in this region is consistent with the decrease in turbulence drive terms and increase in suppression, as shown in Figure 2, and is also consistent with the previous work. 11,12 The turbulent spectra shown here will be compared to the results of gyrokinetic simulations in Sec. III.…”

Section: -3mentioning

confidence: 99%

“…11 for experimental work and Ref. 12 for comparisons with gyrokinetic simulations). This paper focuses on validation of the gyrokinetic model as implemented in the code GYRO 13 in L-and I-mode plasmas, as well as making comparisons between experiment and the reduced gyrofluid model TGLF.…”

Section: Introductionmentioning

confidence: 99%

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Validation of nonlinear gyrokinetic simulations of L- and I-mode plasmas on Alcator C-Mod

et al. 2017

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New validation of global, nonlinear, ion-scale gyrokinetic simulations (GYRO) is carried out for L- and I-mode plasmas on Alcator C-Mod, utilizing heat fluxes, profile stiffness, and temperature fluctuations. Previous work at C-Mod found that ITG/TEM-scale GYRO simulations can match both electron and ion heat fluxes within error bars in I-mode [White PoP 2015], suggesting that multi-scale (cross-scale coupling) effects [Howard PoP 2016] may be less important in I-mode than in L-mode. New results presented here, however, show that global, nonlinear, ion-scale GYRO simulations are able to match the experimental ion heat flux, but underpredict electron heat flux (at most radii), electron temperature fluctuations, and perturbative thermal diffusivity in both L- and I-mode. Linear addition of electron heat flux from electron scale runs does not resolve this discrepancy. These results indicate that single-scale simulations do not sufficiently describe the I-mode core transport, and that multi-scale (coupled electron- and ion-scale) transport models are needed. A preliminary investigation with multi-scale TGLF, however, was unable to resolve the discrepancy between ion-scale GYRO and experimental electron heat fluxes and perturbative diffusivity, motivating further work with multi-scale GYRO simulations and a more comprehensive study with multi-scale TGLF.

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Section: Comparison To Nonlinear Gyro Resultsmentioning

confidence: 99%

“…v PB e depends inversely on density and H-mode tends to have a strong density increase while I-mode does not. 12 …”

Section: -3mentioning

confidence: 99%

Section: -3mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Validation of nonlinear gyrokinetic simulations of L- and I-mode plasmas on Alcator C-Mod

et al. 2017

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“…66,[82][83][84][85][86][87][88][89][90][91][92][93][94] Many other validation studies have assessed the sensitivity of 16 inputs but not explicitly presented the results in the form shown in Fig. 5.…”

Section: Building Robust Local Turbulent Transport Validation Metmentioning

confidence: 99%

Validation metrics for turbulent plasma transport

Holland

2016

Physics of Plasmas

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Developing accurate models of plasma dynamics is essential for confident predictive modeling of current and future fusion devices. In modern computer science and engineering, formal verification and validation processes are used to assess model accuracy and establish confidence in the predictive capabilities of a given model. This paper provides an overview of the key guiding principles and best practices for the development of validation metrics, illustrated using examples from investigations of turbulent transport in magnetically confined plasmas. Particular emphasis is given to the importance of uncertainty quantification and its inclusion within the metrics, and the need for utilizing synthetic diagnostics to enable quantitatively meaningful comparisons between simulation and experiment. As a starting point, the structure of commonly used global transport model metrics and their limitations is reviewed. An alternate approach is then presented, which focuses upon comparisons of predicted local fluxes, fluctuations, and equilibrium gradients against observation. The utility of metrics based upon these comparisons is demonstrated by applying them to gyrokinetic predictions of turbulent transport in a variety of discharges performed on the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)], as part of a multi-year transport model validation activity.

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Validation of nonlinear gyrokinetic transport models using turbulence measurements

White

2019

J. Plasma Phys.

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This tutorial covers validation of gyrokinetic turbulent-transport models via comparison of measured turbulence with realistic simulations of fusion plasmas. It presents a brief history of validation of gyrokinetic simulations, the principal challenges encountered, a limited survey of common turbulence diagnostics used on tokamaks and stellarators, an overview of the fundamentals of synthetic diagnostic models and a discussion of frontiers in turbulent-transport model validation.

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Nonlinear gyrokinetic simulations of the I-mode high confinement regime and comparisons with experimenta)

Cited by 18 publications

References 44 publications

Validation of nonlinear gyrokinetic simulations of L- and I-mode plasmas on Alcator C-Mod

Validation of nonlinear gyrokinetic simulations of L- and I-mode plasmas on Alcator C-Mod

Validation metrics for turbulent plasma transport

Validation of nonlinear gyrokinetic transport models using turbulence measurements

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