Cziegler, I. orcid.org/0000-0003-1040-8918, Hubbard, A. E., Hughes, J. W. et al. (2 more authors) (2017) Turbulence Nonlinearities Shed Light on Geometric Asymmetry in Tokamak Confinement Transitions. Physical Review Letters. 105003. ISSN 1079-7114
Abstract
A comprehensive study of fully frequency-resolved nonlinear kinetic energy transfer has been performed for the first time in a diverted tokamak, providing new insight into the parametric dependences of edge turbulence transitions. Measurements using gas puff imaging in the turbulent L-mode state illuminate the source of the long known but as yet unexplained "favorable-unfavorable" geometric asymmetry of the power threshold for transition to the turbulence-suppressed H mode. Results from the recently discovered I mode point to a competition between zonal flow (ZF) and geodesic-acoustic modes (GAM) for turbulent energy, while showing new evidence that the I-to-H transition is still dominated by ZFs. The availability of nonlinear drive for the GAM against net heat flux through the edge corresponds very well to empirical scalings found experimentally for accessing the I mode.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2017 American Physical Society. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Physics (York) |
Depositing User: | Pure (York) |
Date Deposited: | 12 Apr 2017 10:40 |
Last Modified: | 16 Oct 2024 13:42 |
Published Version: | https://doi.org/10.1103/PhysRevLett.118.105003 |
Status: | Published |
Refereed: | Yes |
Identification Number: | 10.1103/PhysRevLett.118.105003 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:115001 |