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

JET-EFDA collaborators

Research output: Contribution to journalArticleScientificpeer-review

10 Citations (Scopus)

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/χphiv and the Prandtl number χphiv/χi are in good agreement with the experimental observations, with similar dependences on R/Ln, q and ε = r/R. A contribution due to residual stresses may also be present, but could not be identified with certainty.
Original languageEnglish
Article number114024
JournalNuclear Fusion
Volume52
Issue number11
DOIs
Publication statusPublished - 2012
MoE publication typeA1 Journal article-refereed

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momentum
gradients
rotating plasmas
neutral beams
Prandtl number
residual stress
unity

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JET-EFDA collaborators. / Ubiquity of non-diffusive momentum transport in JET H-modes. In: Nuclear Fusion. 2012 ; Vol. 52, No. 11.
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title = "Ubiquity of non-diffusive momentum transport in JET H-modes",
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/χphiv and the Prandtl number χphiv/χi are in good agreement with the experimental observations, with similar dependences on R/Ln, q and ε = r/R. A contribution due to residual stresses may also be present, but could not be identified with certainty.",
author = "H. Weisen and Y. Camanen and A. Salmi and T.W. Versloot and P.C. Devries and M. Maslov and Tuomas Tala and M. Beurskens and C. Giroud and {JET-EFDA collaborators}",
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Ubiquity of non-diffusive momentum transport in JET H-modes. / JET-EFDA collaborators.

In: Nuclear Fusion, Vol. 52, No. 11, 114024, 2012.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Ubiquity of non-diffusive momentum transport in JET H-modes

AU - Weisen, H.

AU - Camanen, Y.

AU - Salmi, A.

AU - Versloot, T.W.

AU - Devries, P.C.

AU - Maslov, M.

AU - Tala, Tuomas

AU - Beurskens, M.

AU - Giroud, C.

AU - JET-EFDA collaborators

PY - 2012

Y1 - 2012

N2 - 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/χphiv and the Prandtl number χphiv/χi are in good agreement with the experimental observations, with similar dependences on R/Ln, q and ε = r/R. A contribution due to residual stresses may also be present, but could not be identified with certainty.

AB - 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/χphiv and the Prandtl number χphiv/χi are in good agreement with the experimental observations, with similar dependences on R/Ln, q and ε = r/R. A contribution due to residual stresses may also be present, but could not be identified with certainty.

U2 - 10.1088/0029-5515/52/11/114024

DO - 10.1088/0029-5515/52/11/114024

M3 - Article

VL - 52

JO - Nuclear Fusion

JF - Nuclear Fusion

SN - 0029-5515

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ER -