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Density Impact on toroidal rotation in Tore Supra: experimental observations and theoretical investigation   

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L’article “Density Impact on toroidal rotation in Tore Supra: experimental observations and theoretical investigation” (J. Bernardo, C. Fenzi, C Bourdelle, Y Camenen, H Arnichand, João P S Bizarro, S Cortes, X Garbet, Z O Guimarães-Filho, T Aniel, J-F Artaud, F Clairet, P Cottier, J Gunn, P Lotte and the Tore Supra Team) a été sélectionné pour apparaître dans les PPCF highlights 2015 (http://iopscience.iop.org/0741-3335/page/highlights-of-2015). Cet article porte sur les résultats du travail de thèse de Joao Bernardo, collaborateur IST co-encadré par C. Fenzi durant sa thèse :
Abstract
The effect of plasma density on toroidal rotation was examined in density ramp-up experiments at a plasma current of 1 MA and a toroidal magnetic field of 3.6 T in Tore Supra ohmic discharges. Experimental measurements have shown that the toroidal rotation amplitude is reduced at all radii when increasing the plasma density, although it remains in the counter-current direction. Neoclassical predictions including ripple-induced toroidal friction are in qualitative agreement with such observations. However, in the core (r/a < 0.5) the plasma accelerates at nl ~ 3 × 1019 m−2 and breaks again above nl ~ 3.5 × 1019 m−2. This rotation bifurcation did not appear to be correlated to a possible influence of the sawtooth activity. Nonetheless, quasi-linear gyrokinetic simulations have shown that the transition of the nature of linear microinstabilities from ITG-TEM to pure ITG occurs at nl ~ 3 × 1019 m−2, which could indicate a change on the turbulence driven contributions and explain the deviation from neoclassical predictions in the plasma core.
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vi214773, 2018-08-09
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