The 2008 Public Release of the International Multi-tokamak Confinement Profile Database

Roach, C. M.; Walters, M.; Budny, R.; Imbeaux, F.; Fredian, T.; Greenwald, M.; Stillermann, J. A.; Alexander, David; Carlsson, Johan; Cary, John R.; Ryter, F.; Stöber, J.; Gohil, P.; Greenfield, C. M.; Murakami, M.; Bracco, G.; Esposito, B.; Romanelli, M.; Parail, V.; Stubberfield, P.M.; Voitsekhovitch, I.; Brickley, C.; Field, A. R.; Sakamoto, Y.; Fujita, T.; Fukuda, T.; Haysahi, N.; Hogeweij, G. M. D.; Chudnovskiy, A. N.; Kinerva, N. A.; Kessel, C.; Aniel, T.; Hoang, G. T.; Ongena, J.; Doyle, E. J.; Houlberg, W. A.; Polevoi, A.; Database, Itpa Confinement

doi:10.1088/0029-5515/48/12/125001

Cited by 40 publications

(44 citation statements)

References 155 publications

(286 reference statements)

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“…First, only figure of merit 4, which to the author's knowledge has not been widely used in published MFE transport modeling validation studies, incorporates any estimate of experimental or model uncertainties. Previous studies using other figures of merit implicitly address this issue by assessing model performance using databases of experimental discharges (including those assembled by the ITER Topical Physics Activity Transport and Confinement working group 79 ), and looking at ensemble statistics of the metrics (illustrated in Fig. 4), but this approach is not a completely satisfying substitute for explicitly confronting the …”

Section: A Historical Transport Modeling Metricsmentioning

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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Section: A Historical Transport Modeling Metricsmentioning

confidence: 99%

Validation metrics for turbulent plasma transport

Holland

2016

Physics of Plasmas

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“…TRINITY is currently capable of both an analytic and numerical specification of these quantities, with experimental values taken from the publicly accessible ITER profile database. 36 Once these quantities are obtained at each of the radial grid points, TRINITY calls a solver for the fluxes. For the ion neoclassical heat flux, TRINITY currently uses the simplified analytic model given in Ref.…”

Section: B Schematicmentioning

confidence: 99%

Direct multiscale coupling of a transport code to gyrokinetic turbulence codes

et al. 2010

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Direct coupling between a transport solver and local, nonlinear gyrokinetic calculations using the multiscale gyrokinetic code TRINITY [M. Barnes, Ph.D. thesis, arXiv:0901.2868] is described. The coupling of the microscopic and macroscopic physics is done within the framework of multiscale gyrokinetic theory, of which we present the assumptions and key results. An assumption of scale separation in space and time allows for the simulation of turbulence in small regions of the space-time grid, which are embedded in a coarse grid on which the transport equations are implicitly evolved. This leads to a reduction in computational expense of several orders of magnitude, making firstprinciples simulations of the full fusion device volume over the confinement time feasible on current computing resources. Numerical results from TRINITY simulations are presented and compared with experimental data from JET and ASDEX Upgrade plasmas.

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“…Some initial studies of shaping effects with GS2 were carried out in Ref. 21, using a range of shapes scaled from the particular JET shot #52979 (available in the ITER profile database 26 ). This JET shot, described in more detail in Refs.…”

Section: Ncsx Vs a Shaped Tokamakmentioning

confidence: 99%

Comparing Linear Microinstability of the National Compact Stellarator Expriment and a Shaped Tokamak

Baumgaertel¹,

Hammett²,

Mikkelsen³

2012

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One metric for comparing confinement properties of different magnetic fusion energy configurations is the linear critical gradient of drift wave modes. The critical gradient scale length determines the ratio of the core to pedestal temperature when a plasma is limited to marginal stability in the plasma core. The gyrokinetic turbulence code GS2 was used to calculate critical temperature gradients for the linear, collisionless ion temperature gradient (ITG) mode in the National Compact Stellarator Experiment (NCSX) and a prototypical shaped tokamak, based on the profiles of a JET H-mode shot and the stronger shaping of ARIES-AT. While a concern was that the narrow cross section of NCSX at some toroidal locations would result in steep gradients that drive instabilities more easily, it is found that other stabilizing effects of the stellarator configuration offset this so that the normalized critical gradients for NCSX are competitive with or even better than for the tokamak. For the adiabatic ITG mode, NCSX and the tokamak had similar critical gradients, though beyond marginal stability, NCSX had larger growth rates. However, for the kinetic ITG mode, NCSX had a higher critical gradient and lower growth rates until a/L T ≈ 1.5 a/L T,crit , when it surpassed the tokamak's. A discussion of the results presented with respect to a/L T vs R/L T is included.

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The 2008 Public Release of the International Multi-tokamak Confinement Profile Database

Cited by 40 publications

References 155 publications

Validation metrics for turbulent plasma transport

Validation metrics for turbulent plasma transport

Direct multiscale coupling of a transport code to gyrokinetic turbulence codes

Comparing Linear Microinstability of the National Compact Stellarator Expriment and a Shaped Tokamak

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