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Ubiquity of non-diffusive momentum transport in JET H-modes

Author
Abstract

A broad survey of the experimental database of neutral beam heated baseline H-modes and hybrid scenarios in the JET tokamak has established the ubiquity of non-diffusive momentum transport mechanisms in rotating plasmas. As a result of their presence, the normalized angular frequency gradient R ∇ ω / ω is higher than expected from momentum diffusion alone, by about unity in the core ( r / a ∼ 0.3), rising to near 5 close to the edge, where its contribution to the total gradient is comparable to the gradient associated with the diffusive flux. The magnitude and parameter dependences of the non-diffusive contribution to the gradient are consistent with a theoretically expected pinch, which has its origin in the vertical particle drift resulting from the Coriolis force. Linear gyrokinetic calculations of the pinch number RV / χ φ and the Prandtl number χ φ / χ i are in good agreement with the experimental observations, with similar dependences on R / L n , q and ε = r / R . A contribution due to residual stresses may also be present, but could not be identified with certainty.

Year of Publication
2012
Journal
Nuclear Fusion
Volume
52
Number
11
Number of Pages
114024
URL
http://www.iop.org/Jet/article?EFDP11051&EFDP11055
DOI
10.1088/0029-5515/52/11/114024
PId
4b4ec77675b7d97300fd63aed60dd6e8
Alternate Journal
Nucl. Fusion
Label
OA
Journal Article
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