# NBI Modulation Experiments to Study Momentum Transport and Magnetic Field Induced Ripple Torque on JET

Tuomas Tala, Antti 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, J. Weiland, K.-D. Zastrow, JET-EFDA contributors

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

## Abstract

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 $-Rv_{pinch}/\chi\phi = 1.2R/L_n + 1.4$. There is no dependence of the pinch number on collisionality. The Prandtl number was not found to depend either on R/Ln, collisionality or on q. The gyrokinetic 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. The extrapolation of these results to ITER illustrates that at 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 language English Proceedings 38th EPS Conference on Plasma Physics, EPS 2011 A. Becoulet European Physical Society 605-608 1 2-914771-68-1, 978-1-6183-9593-1 Published - 2011 A4 Article in a conference publication 38th EPS Conference on Plasma Physics - Strasbourg, FranceDuration: 27 Jun 2011 → 1 Jul 2011

### Conference

Conference 38th EPS Conference on Plasma Physics EPS 2011 France Strasbourg 27/06/11 → 1/07/11

## Keywords

• plasma physics

## Fingerprint

Dive into the research topics of 'NBI Modulation Experiments to Study Momentum Transport and Magnetic Field Induced Ripple Torque on JET'. Together they form a unique fingerprint.