H-mode pedestal scaling in DIII-D, ASDEX Upgrade, and JET

Beurskens, M.; Osborne, T.H.; Schneider, P. A.; Wolfrum, E.; Frassinetti, L.; Groebner, R. J.; Lomas, P. J.; Nunes, I.; Saarelma, S.; Scannell, R.; Snyder, P. B.; Zarzoso, D.; Balboa, I.; Bray, B.D.; Brix, M.; Flanagan, J.; Giroud, C.; Giovannozzi, E.; Kempenaars, M.; Loarte, A.; Luna, E. de la; Maddison, G.; Maggi, C. F.; McDonald, D. C.; Pasqualotto, R.; Saibene, G.; Sartori, R.; Solano, E.R.; Walsh, M. J.; Zabeo, L.; Team, Diii-D; Contributors, Jet‐Efda

doi:10.1063/1.3593008

Cited by 79 publications

(144 citation statements)

References 34 publications

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“…Previous studies which discuss EPED1 predictions of the JET pedestal include [Beurskens-PPCF-2009, Beurskens 2011, Leyland 2013, Beurskens 2014. The earlier multi machine comparisons (JET, DIII-D measurements [Beurskens-PPCF-2009] and JET, DIII-D, AUG measurements [Beurskens 2011]) concluded there is a good agreement between the predicted and measured pedestal height.…”

Section: Figure 2 Deconvolved Modified Hyperbolic Tangent Fits To Ramentioning

confidence: 97%

“…The earlier multi machine comparisons (JET, DIII-D measurements [Beurskens-PPCF-2009] and JET, DIII-D, AUG measurements [Beurskens 2011]) concluded there is a good agreement between the predicted and measured pedestal height. The conclusion from more recent extensive comparisons, dedicated to JET-C [Leyland 2013] and JET-ILW [Beurskens 2014] measurements, is more complex as, for example, there are discrepancies between the predicted and measured pedestal height at high deuterium fuelling (JET-C) and high nitrogen seeding (JET-ILW).…”

Section: Figure 2 Deconvolved Modified Hyperbolic Tangent Fits To Ramentioning

confidence: 99%

“…The poloidal pedestal normalised pressure (β pol,ped ) is calculated using the expression given by [Beurskens 2011, Leyland 2013,…”

Section: Description Of Databasementioning

confidence: 99%

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The H-mode pedestal structure and its role on confinement in JET with a carbon and metal wall

Leyland

Beurskens

Frassinetti³

et al. 2014

Nucl. Fusion

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We present the pedestal structure, as determined from the high resolution Thomson scattering (HRTS) measurements, for a database of low and high triangularity (  0.22-0.39) 2.5MA, Type I ELMy H-mode JET plasmas after the installation of the new ITER-like Wall (JET-ILW). The database explores the effect of increasing deuterium fuelling and nitrogen seeding with a view to explain the observed changes in performance (edge and global). The low triangularity JET-ILW plasmas show no significant change in performance and pedestal structure with increasing gas dosing. These results are in good agreement with EPED1 predictions. At high triangularity, for pure deuterium fuelled JET-ILW plasmas, there is a 20-30% reduction in global performance and pressure pedestal height in comparison to JET-C plasmas. This reduction in performance is primarily due to a degradation of the temperature pedestal height. The global performance and pressure pedestal height of JET-ILW plasmas can be partially recovered to that of JET-C plasmas with additional nitrogen seeding [Giroud 2013]. This observed improvement in performance is predominately due to a significant increase in density pedestal height as well as a small increase in the temperature pedestal height. A key result with increasing deuterium fuelling for JET-ILW plasmas is there is no improvement in pressure pedestal height however the pedestal still widens which is inconsistent with the  = 0.076√ pol,ped scaling. Furthermore, a key result with increasing nitrogen seeding is the pressure pedestal widening is due to an increase in the temperature pedestal width whilst the density pedestal shows no clear trend. The comparison of EPED1 predictions with the measurements at high triangularity is complex as, for example, for pure deuterium fuelled plasmas there is very good agreement for the pedestal height but not the width. In addition, current EPED1 runs under-predict the pedestal height and width at high nitrogen seeding for JET-ILW plasmas however further work is required to determine the significance of these deviations. Understanding these deviations is essential as provides an insight to the physical mechanisms governing the pedestal structure and edge performance.

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Section: Figure 2 Deconvolved Modified Hyperbolic Tangent Fits To Ramentioning

confidence: 97%

Section: Figure 2 Deconvolved Modified Hyperbolic Tangent Fits To Ramentioning

confidence: 99%

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The H-mode pedestal structure and its role on confinement in JET with a carbon and metal wall

Leyland

Beurskens

Frassinetti³

et al. 2014

Nucl. Fusion

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“…When considering also JET data the difference in density might also help to explain the deviation. The neutral penetration model [22] would go in the right direction and showed promising results [10], but was never tested on all 4 machines. In this context it is important to note that the argumentation for the electron pressure width does not apply to T e , n e or T i .…”

Section: Electron Density and Pressure Gradientsmentioning

confidence: 99%

“…In the recent years a lot of effort was focused on documenting and understanding the basic properties of the pedestal -its gradients [2,4,5], widths [6][7][8][9][10][11][12] and top values [13][14][15]. This paper focuses on the pedestal characteristics, in particular the gradients, just before the onset of an edge localized mode (ELM) in type-I ELMy H-modes.…”

Section: Introductionmentioning

confidence: 99%

Analysis of temperature and density pedestal gradients in AUG, DIII-D and JET

et al. 2013

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Abstract:A comparison of the AUG and DIII-D temperature pedestals showed significant differences between electrons and ions. For high collision rates the ions are coupled to the electrons and show very similar pedestal top values and gradients. For lower collision rates both decouple and the ion pedestal becomes less steep. The electron temperature gradient scales linearly with its pedestal top value. This trend is independent of collisionality and plasma shape. The normalized total pressure gradient α shows strong correlations with the plasma shape in a way expected by peeling-ballooning theory. The different behaviours of the electron temperature gradient only and the total pedestal pressure gradient suggests a limit for the electron temperature pedestal different from linear edge MHD stability.

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Applications of Bayesian temperature profile reconstruction to automated comparison with heat transport models and uncertainty quantification of current diffusion

Irishkin

Imbeaux

Aniel

et al. 2015

Fusion Engineering and Design

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Please cite this article in press as: M. Irishkin, et al., Applications of Bayesian temperature profile reconstruction to automated comparison with heat transport models and uncertainty quantification of current diffusion, Fusion Eng. Des. (2015), http://dx.h i g h l i g h t s• We developed a method for automated comparison of experimental data with models.• A unique platform implements Bayesian analysis and integrated modelling tools.• The method is tokamak-generic and is applied to Tore Supra and JET pulses.• Validation of a heat transport model is carried out.• We quantified the uncertainties due to Te profiles in current diffusion simulations. a b s t r a c tIn the context of present and future long pulse tokamak experiments yielding a growing size of measured data per pulse, automating data consistency analysis and comparisons of measurements with models is a critical matter. To address these issues, the present work describes an expert system that carries out in an integrated and fully automated way (i) a reconstruction of plasma profiles from the measurements, using Bayesian analysis (ii) a prediction of the reconstructed quantities, according to some models and (iii) a comparison of the first two steps. The first application shown is devoted to the development of an automated comparison method between the experimental plasma profiles reconstructed using Bayesian methods and time dependent solutions of the transport equations. The method was applied to model validation of a simple heat transport model with three radial shape options. It has been tested on a database of 21 Tore Supra and 14 JET shots. The second application aims at quantifying uncertainties due to the electron temperature profile in current diffusion simulations. A systematic reconstruction of the Ne, Te, Ti profiles was first carried out for all time slices of the pulse. The Bayesian 95% highest probability intervals on the Te profile reconstruction were then used for (i) data consistency check of the flux consumption and (ii) defining a confidence interval for the current profile simulation. The method has been applied to one Tore Supra pulse and one JET pulse.

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H-mode pedestal scaling in DIII-D, ASDEX Upgrade, and JET

Abstract: Abstract

Cited by 79 publications

References 34 publications

The H-mode pedestal structure and its role on confinement in JET with a carbon and metal wall

The H-mode pedestal structure and its role on confinement in JET with a carbon and metal wall

Analysis of temperature and density pedestal gradients in AUG, DIII-D and JET

Applications of Bayesian temperature profile reconstruction to automated comparison with heat transport models and uncertainty quantification of current diffusion

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