Predictive analysis of q-profile influence on transport in JET and ASDEX Upgrade hybrid scenarios

TitlePredictive analysis of q-profile influence on transport in JET and ASDEX Upgrade hybrid scenarios
Publication TypeJournal Article
Year of Publication2012
AuthorsJ. Citrin, J. Hobirk, M. Schneider, J.F Artaud, C. Bourdelle, K. Crombe, G.MD Hogeweij, F. Imbeaux, E. Joffrin, F. Koechl, J. Stober
Corporate AuthorsASDEX Upgrade Team, JET-EFDA Contributors, ITM-TF ITER Scenario Modelling Group
JournalPlasma Physics and Controlled Fusion
Volume54
Number6
Pagination065008
Date PublishedJun
Type of ArticleArticle
ISBN Number0741-3335
KeywordsBARRIERS, CONFINEMENT, DIII-D TOKAMAK, HIGH-PERFORMANCE DISCHARGES, IMPROVED H-MODE, ITER, OPERATION, SIMULATIONS, STABILITY, TORE-SUPRA
Abstract

Hybrid scenarios in present machines are often characterized by improved confinement compared with the IPB98(y, 2) empirical scaling law expectations. This work concentrates on isolating the impact of increased s/q at outer radii (where s is the magnetic shear) on core confinement in low-triangularity JET and ASDEX Upgrade (AUG) experiments. This is carried out by predictive heat and particle transport modelling using the integrated modelling code CRONOS coupled to the GLF23 turbulent transport model. For both machines, discharge pairs were analysed displaying similar pedestal confinement yet significant differences in core confinement. From these comparisons, it is found that s/q shaping at outer radii may be responsible for up to similar to 50% of the relative core confinement improvement observed in these specific discharges. This relative improvement is independent of the degree of rotational shear turbulence suppression assumed in the GLF23 model. However, employing the full GLF23 rotational shear model leads to an overprediction of the ion temperatures in all discharges analysed. Additional mechanisms for core confinement improvement are discussed and estimated. Further linear threshold analysis with QuaLiKiz is carried out on both pairs of discharges. This work aims to validate recent predictions of the ITER hybrid scenario also employing CRONOS/GLF23, where a high level of confinement and resultant fusion power sensitivity to the s/q profile was found.

DOI10.1088/0741-3335/54/6/065008
Division

FP

Department

CPP-HT

PID

bda1f42e30092cecb77d13ab81a2b6af

Alternate TitlePlasma Phys. Control. Fusion
LabelOA
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