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Increased Nonlinear Coupling between Turbulence and Low-Frequency Fluctuations at the L-H Transition

Journal Article · · Physical Review Letters
The nonlinear coupling between small scale high-frequency turbulence and larger scale lower-frequency fluctuations increases transiently in transitions to improved confinement in the DIII-D tokamak. This increase starts before the rapid turbulence suppression and E x B shear-flow development in the region that becomes the H -mode transport barrier/shear flow region. After the transition, the coupling returns to L -mode levels. These results are consistent with expectations for spontaneous transitions to improved confinement triggered by a turbulence-driven sheared flow.
Sponsoring Organization:
(US)
DOE Contract Number:
FG03-95ER54294; FG03-99ER54553
OSTI ID:
40277663
Journal Information:
Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 13 Vol. 87; ISSN 0031-9007
Publisher:
The American Physical Society
Country of Publication:
United States
Language:
English

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