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NBI modulation experiments to study momentum transport and magnetic field induced ripple torque on JET

T. Tala ; A. Salmi ; P. Mantica ; C. Angioni ; G. Corrigan ; P.C. de Vries ; C. Giroud ; J. Ferreira ; J. Lönnroth ; V. Naulin ; A.G. Peeters ; W. Solomon ; D. Strintzi ; M. Tsalas ; T.W. Versloot ; Jan Weiland (Institutionen för rymd- och geovetenskap) ; K.-D. Zastrow
38th EPS Conference on Plasma Physics 2011, EPS 2011. Strasbourg, 27 June - 1 July 2011 p. 605-608. (2011)
[Konferensbidrag, refereegranskat]

Several parametric scans have been performed to study momentum transport on JET. NBI modulation technique has been applied to separating 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 -Rv pmch/ X φ= 1.2RJL n + 1.4. There is no dependence of the pinch number on collisionality. The Prandtl number was not found to depend either on R/L n, collisionality or on q. The gyro- kinetic simulations show qualitatively similar dependence of the pinch number on R/L n, 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. The extrapolation of these results to ITER illustrates that at R/L n>2 the pinch number becomes large enough (> 3-4) to make the rotation profile peaked provided that the edge rotation is non-zero. 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.

Nyckelord: 3D effects, Absolute values, Collisionality, Core rotation, Experimental values, Inverse density, Kinetic simulation, Modulation techniques, Momentum transports, Parametric dependence, Plasma edges, Ripple torque



Denna post skapades 2012-11-16.
CPL Pubid: 166259

 

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Institutionen för rymd- och geovetenskap

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