Parametric dependences of momentum pinch and Prandtl number in JET

JET-EFDA collaborators

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Abstract

Several parametric scans have been performed to study momentum transport on JET. A neutral beam injection modulation technique has been applied to separate the diffusive and convective momentum transport terms. The magnitude of the inward momentum pinch depends strongly on the inverse density gradient length, with an experimental scaling for the pinch number being -Rvpinch / χφ = 1.2R/Ln + 1.4. There is no dependence of the pinch number on collisionality, whereas the pinch seems to depend weakly on q-profile, the pinch number decreasing with increasing q. The Prandtl number was not found to depend either on R/Ln, collisionality or on q. The gyro-kinetic simulations show qualitatively similar dependence of the pinch number on R/Ln, but the dependence is weaker in the simulations. Gyro-kinetic simulations do not find any clear parametric dependence in the Prandtl number, in agreement with experiments, but the experimental values are larger than the simulated ones, in particular in L-mode plasmas. The extrapolation of these results to ITER illustrates that at large enough R/Ln > 2 the pinch number becomes large enough (>3–4) to make the rotation profile peaked, provided that the edge rotation is non-zero. And this rotation peaking can be achieved with small or even with no core torque source. The absolute value of the core rotation is still very challenging to predict partly due to the lack of the present knowledge of the rotation at the plasma edge, partly due to insufficient understanding of 3D effects like braking and partly due to the uncertainties in the extrapolation of the present momentum transport results to a larger device.
Original languageEnglish
Article number123002
Number of pages11
JournalNuclear Fusion
Volume51
Issue number12
DOIs
Publication statusPublished - 2011
MoE publication typeA1 Journal article-refereed

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Prandtl number
momentum
extrapolation
braking
beam injection
simulation
neutral beams
kinetics
profiles
torque
modulation
scaling
gradients

Cite this

JET-EFDA collaborators. / Parametric dependences of momentum pinch and Prandtl number in JET. In: Nuclear Fusion. 2011 ; Vol. 51, No. 12.
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title = "Parametric dependences of momentum pinch and Prandtl number in JET",
abstract = "Several parametric scans have been performed to study momentum transport on JET. A neutral beam injection modulation technique has been applied to separate the diffusive and convective momentum transport terms. The magnitude of the inward momentum pinch depends strongly on the inverse density gradient length, with an experimental scaling for the pinch number being -Rvpinch / χφ = 1.2R/Ln + 1.4. There is no dependence of the pinch number on collisionality, whereas the pinch seems to depend weakly on q-profile, the pinch number decreasing with increasing q. The Prandtl number was not found to depend either on R/Ln, collisionality or on q. The gyro-kinetic simulations show qualitatively similar dependence of the pinch number on R/Ln, but the dependence is weaker in the simulations. Gyro-kinetic simulations do not find any clear parametric dependence in the Prandtl number, in agreement with experiments, but the experimental values are larger than the simulated ones, in particular in L-mode plasmas. The extrapolation of these results to ITER illustrates that at large enough R/Ln > 2 the pinch number becomes large enough (>3–4) to make the rotation profile peaked, provided that the edge rotation is non-zero. And this rotation peaking can be achieved with small or even with no core torque source. The absolute value of the core rotation is still very challenging to predict partly due to the lack of the present knowledge of the rotation at the plasma edge, partly due to insufficient understanding of 3D effects like braking and partly due to the uncertainties in the extrapolation of the present momentum transport results to a larger device.",
author = "Tuomas Tala and Antti Salmi and C. Angioni and F.J. Casson and G Corrigan and J. Ferreira and C Giroud and P. Mantica and V. Naulin and Peeters, {A. G.} and W.M. Solomon and D. Strintzi and M. Tsalas and Versloot, {T. W.} and K.-D. Zastrow and {JET-EFDA collaborators}",
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doi = "10.1088/0029-5515/51/12/123002",
language = "English",
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Parametric dependences of momentum pinch and Prandtl number in JET. / JET-EFDA collaborators.

In: Nuclear Fusion, Vol. 51, No. 12, 123002, 2011.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Parametric dependences of momentum pinch and Prandtl number in JET

AU - Tala, Tuomas

AU - Salmi, Antti

AU - Angioni, C.

AU - Casson, F.J.

AU - Corrigan, G

AU - Ferreira, J.

AU - Giroud, C

AU - Mantica, P.

AU - Naulin, V.

AU - Peeters, A. G.

AU - Solomon, W.M.

AU - Strintzi, D.

AU - Tsalas, M.

AU - Versloot, T. W.

AU - Zastrow, K.-D.

AU - JET-EFDA collaborators

PY - 2011

Y1 - 2011

N2 - Several parametric scans have been performed to study momentum transport on JET. A neutral beam injection modulation technique has been applied to separate the diffusive and convective momentum transport terms. The magnitude of the inward momentum pinch depends strongly on the inverse density gradient length, with an experimental scaling for the pinch number being -Rvpinch / χφ = 1.2R/Ln + 1.4. There is no dependence of the pinch number on collisionality, whereas the pinch seems to depend weakly on q-profile, the pinch number decreasing with increasing q. The Prandtl number was not found to depend either on R/Ln, collisionality or on q. The gyro-kinetic simulations show qualitatively similar dependence of the pinch number on R/Ln, but the dependence is weaker in the simulations. Gyro-kinetic simulations do not find any clear parametric dependence in the Prandtl number, in agreement with experiments, but the experimental values are larger than the simulated ones, in particular in L-mode plasmas. The extrapolation of these results to ITER illustrates that at large enough R/Ln > 2 the pinch number becomes large enough (>3–4) to make the rotation profile peaked, provided that the edge rotation is non-zero. And this rotation peaking can be achieved with small or even with no core torque source. The absolute value of the core rotation is still very challenging to predict partly due to the lack of the present knowledge of the rotation at the plasma edge, partly due to insufficient understanding of 3D effects like braking and partly due to the uncertainties in the extrapolation of the present momentum transport results to a larger device.

AB - Several parametric scans have been performed to study momentum transport on JET. A neutral beam injection modulation technique has been applied to separate the diffusive and convective momentum transport terms. The magnitude of the inward momentum pinch depends strongly on the inverse density gradient length, with an experimental scaling for the pinch number being -Rvpinch / χφ = 1.2R/Ln + 1.4. There is no dependence of the pinch number on collisionality, whereas the pinch seems to depend weakly on q-profile, the pinch number decreasing with increasing q. The Prandtl number was not found to depend either on R/Ln, collisionality or on q. The gyro-kinetic simulations show qualitatively similar dependence of the pinch number on R/Ln, but the dependence is weaker in the simulations. Gyro-kinetic simulations do not find any clear parametric dependence in the Prandtl number, in agreement with experiments, but the experimental values are larger than the simulated ones, in particular in L-mode plasmas. The extrapolation of these results to ITER illustrates that at large enough R/Ln > 2 the pinch number becomes large enough (>3–4) to make the rotation profile peaked, provided that the edge rotation is non-zero. And this rotation peaking can be achieved with small or even with no core torque source. The absolute value of the core rotation is still very challenging to predict partly due to the lack of the present knowledge of the rotation at the plasma edge, partly due to insufficient understanding of 3D effects like braking and partly due to the uncertainties in the extrapolation of the present momentum transport results to a larger device.

U2 - 10.1088/0029-5515/51/12/123002

DO - 10.1088/0029-5515/51/12/123002

M3 - Article

VL - 51

JO - Nuclear Fusion

JF - Nuclear Fusion

SN - 0029-5515

IS - 12

M1 - 123002

ER -