Gyrokinetic study of turbulence suppression in a JET-ILW power scan

TitleGyrokinetic study of turbulence suppression in a JET-ILW power scan
Publication TypeJournal Article
Year of Publication2016
AuthorsH. Doerk, C. Challis, J. Citrin, J. Garcia, T. Gorler, F. Jenko, JET Contributors
JournalPlasma Physics and Controlled Fusion
Volume58
Issue11
Number11
Pagination115005
Date PublishedNov
ISBN Number0741-3335
Abstract

For exploring tokamak operation regimes that deliver both high beta and good energy confinement, power scans at JET with ITER-like wall have been performed. Relatively weak degradation of the confinement time coincides with increased core temperature of the ions at high power. The changes in core turbulence characteristics during a power scan with an optimized (broad) q profile are analyzed by means of nonlinear gyrokinetic simulations. The increase in beta is crucial for stabilizing ion temperature gradient driven turbulence, accompanied by increased ion to electron temperature ratio, the presence of a dynamic fast ion species, as well as the geometric stabilization by increased thermal and suprathermal pressure. A sensitivity study with respect to the q profile reveals that electromagnetic effects are more pronounced at larger values of q. Further, it is confirmed that turbulence suppression due to rotation becomes less effective in such strongly electromagnetic systems. Electrostatic simplified models may thus perform well in present-day devices, in which high beta is often correlated with high rotation, but provide poor extrapolation towards low rotation devices. Implications for ITER and reactor plasmas are discussed.

URLhttp://www.euro-fusionscipub.org/wp-content/uploads/WPJET1PR16_15828_submitted.pdf
DOI10.1088/0741-3335/58/11/115005
Division

FP

Department

IMT

PID

4c63548b9ee1a5f0fa742d00cde333d3

Alternate TitlePlasma Phys. Control. Fusion
LabelOA

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