A new gyrokinetic quasilinear transport model applied to particle transport in tokamak plasmas

Bourdelle, C.; Garbet, X.; Imbeaux, F.; Casati, A.; Dubuit, N.; Guirlet, R.; Parisot, Thomas

doi:10.1063/1.2800869

Cited by 192 publications

(271 citation statements)

References 37 publications

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“…1 From henceforth, we will also refer to the eigenvalue solver as part of 'the QuaLiKiz model.' The fluxes can be schematically decomposed into contributions of the linear response and the saturated electrostatic potential C; Q i ; Q e ¼ X k h ;x;x kj ImðR C;Q i ;Q e lin ðk h ; x; x kj ÞÞ d/ðk h ; x; x kj Þ 2 ;…”

Section: Review Of the Qualikiz Modelmentioning

confidence: 99%

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Quasilinear transport modelling at low magnetic shear

et al. 2012

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Accurate and computationally inexpensive transport models are vital for routine and robust predictions of tokamak turbulent transport. To this end, the QuaLiKiz [Bourdelle et al., Phys. Plasmas 14, 112501 (2007)] quasilinear gyrokinetic transport model has been recently developed. QuaLiKiz flux predictions have been validated by non-linear simulations over a wide range in parameter space. However, a discrepancy is found at low magnetic shear, where the quasilinear fluxes are significantly larger than the non-linear predictions. This discrepancy is found to stem from two distinct sources: the turbulence correlation length in the mixing length rule and an increase in the ratio between the quasilinear and non-linear transport weights, correlated with increased non-linear frequency broadening. Significantly closer agreement between the quasilinear and non-linear predictions is achieved through the development of an improved mixing length rule, whose assumptions are validated by non-linear simulations. V C 2012 American Institute of Physics.

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Section: Review Of the Qualikiz Modelmentioning

confidence: 99%

“…With this goal in mind, the QuaLiKiz quasi-linear transport model has been developed. 1 Particle and heat flux calculation time in QuaLiKiz is $50 000 less than in local non-linear codes. Fluxes computed by QuaLiKiz have been validated by non-linear GYRO 2,3 simulations over a wide range of parameter space.…”

Section: Introductionmentioning

confidence: 99%

Quasilinear transport modelling at low magnetic shear

et al. 2012

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“…Such a rule usually consists of an assumption on the shape of the transport spectrum (or the saturated electrostatic potential) and a saturation amplitude, which is derived, e.g., from mixing length estimates 67 or obtained by fitting an ad-hoc formula to nonlinear simulations. 11 Present quasilinear models have mainly been benchmarked/calibrated to simulations of core plasma turbulence-saturated turbulence levels outside this parameter regime are therefore likely to deviate from the model predictions.…”

Section: Consequences For Quasilinear Modelingmentioning

confidence: 99%

Characterizing turbulent transport in ASDEX Upgrade L-mode plasmas via nonlinear gyrokinetic simulations

et al. 2013

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The nature and level of turbulent transport in the outer core of low-confinement (L-mode) discharges performed at the ASDEX Upgrade tokamak [A. Kallenbach et al., Nucl. Fusion 51, 094012 (2011)] are examined. Previously, it was found that for an L-mode discharge of the DIII-D tokamak [J. L. Luxon and L. G. Davis, Fusion Technol. 8, 441 (1985)] gyrokinetic simulations were unable to reproduce the experimental ion heat flux, underestimating it by almost an order of magnitude. In the present work, employing the GENE gyrokinetic turbulence code, an extensive nonlinear study is performed for L-mode discharges of ASDEX Upgrade in order to cross-check this observation. It is shown that no systematic underprediction can be found in these simulations-instead, discrepancies with respect to experimental transport levels are small enough to be resolved within the uncertainties of the experimental profiles. Moreover, it is shown that some turbulence properties resemble closely those of the underlying linear microinstabilities at least out to 90% of the minor radius, so that quasilinear transport models remain in principle applicable even for these parameters, provided that appropriate nonlinear saturation rules can be developed.

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“…It is then convolved with a second model for the fluctuation spectral intensity hjṽ r;k j 2 i which may come from calibration of the model against experimental data, 69 analytic theory arguments, 36,70,71 or fits to databases of nonlinear simulations. 46,72,73 The underlying physical motivation for this approach is that unlike many neutral fluid turbulence systems, in the core region of MFE-relevant core plasmas, the fluctuations saturate at small amplitude and retain many of the linear wave characteristics of the underlying instabilities.…”

Section: Basics Of Turbulence and Transport Modeling In Magneticmentioning

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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A new gyrokinetic quasilinear transport model applied to particle transport in tokamak plasmas

Cited by 192 publications

References 37 publications

Quasilinear transport modelling at low magnetic shear

Quasilinear transport modelling at low magnetic shear

Characterizing turbulent transport in ASDEX Upgrade L-mode plasmas via nonlinear gyrokinetic simulations

Validation metrics for turbulent plasma transport

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