Impact of heating and current drive mix on the ITER hybrid scenario

TitleImpact of heating and current drive mix on the ITER hybrid scenario
Publication TypeJournal Article
Year of Publication2010
AuthorsJ. Citrin, J.F Artaud, J. Garcia, G.MD Hogeweij, F. Imbeaux
JournalNuclear Fusion
Volume50
Number11
Pagination16
Date PublishedNov
Type of ArticleArticle
ISBN Number0029-5515
Accession NumberISI:000283715500010
KeywordsASDEX UPGRADE, CONFINEMENT, CURRENT-DENSITY PROFILE, DIII-D, DISCHARGES, IMPROVED H-MODE, PHYSICS BASIS, TEMPERATURE, TOKAMAKS, TRANSPORT
Abstract

Hybrid scenario performance in ITER is studied with the CRONOS integrated modelling suite, using the GLF23 anomalous transport model for heat transport prediction. GLF23 predicted core confinement is optimized through tailoring the q-profile shape by a careful choice of current drive actuators, affecting the transport due to the predicted dependence of the turbulence level on the absolute q-profile values and magnetic shear. A range of various heating and current drive choices are examined, as are different assumptions on the pedestal height. The optimum q-profile shape is predicted to be one that maximizes the ratio of s/q throughout the bulk of the plasma volume. Optimizing the confinement allows a minimization of the plasma density required in order to achieve a defined target fusion power of 350 MW. A lower density then allows a lower total current (I-p) at the same Greenwald fraction (f(G)), thus aiding in maintaining q > 1 as desired in a hybrid scenario, and in minimizing the flux consumption. The best performance is achieved with a combination of NBI and ECCD (e.g. 33/37 MW NBI/ECCD for a scenario with a pedestal height of 4 keV). The q-profile shape and plasma confinement properties are shown to be highly sensitive to the positioning of the ECCD deposition. Comparisons with the lower performing cases where some or all of the ECCD power is replaced with LHCD or ICRH are shown (e. g. 33/20/17 MW NBI/ECCD/LHCD or NBI/ECCD/ICRH). The inclusion of LHCD reduces confinement due to deleterious shaping of the q-profile, and the inclusion of ICRH, particularly in a stiff model, does not lead to significantly increased fusion power and furthermore does not contribute to the non-inductive current fraction. For the optimum NBI/ECCD current drive mix, the predictions show that a satisfactory ITER hybrid scenario (P-fus similar to 350 MW, Q >= 5, q(min) close to 1) may be achieved with T-ped >= 4 keV. In addition, predicted performance sensitivity analysis was carried out for several assumed parameters, such as Z(eff) and density peaking.

URL<Go to ISI>://000283715500010
Division

Fusion Physics

PID

a2916b85d88e213309eb95ba705285ff

Alternate TitleNucl. Fusion

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