DIFFER
DIFFER Publication

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

Author
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.

Year of Publication
2016
Journal
Plasma Physics and Controlled Fusion
Volume
58
Number
11
Issue
11
Number of Pages
115005
Date Published
Nov
ISBN Number
0741-3335
URL
http://www.euro-fusionscipub.org/wp-content/uploads/WPJET1PR16_15828_submitted.pdf
DOI
10.1088/0741-3335/58/11/115005
PId
4c63548b9ee1a5f0fa742d00cde333d3
Alternate Journal
Plasma Phys. Control. Fusion
Label
OA
Journal Article
Download citation