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Modélisation et simulation de l'interaction multi-échelles entre îlots magnétiques et la microturbulence dans les plasmas de fusion magnétisés

Abstract : In a tokamak, it exists many kind of instability at the origin of a dammage of the confinement and worst of a lost of a confinement. This phd presents a study of the dynamics of a magnetic island in presence of turbulence in magnetized plasmas. More precisely, the goal is to understand the multi-scales interaction between turbulence, generated by a pressure gradient and the magnetic field curvature, and a magnetic island formed thanks to a tearing mode. Thanks to the derivation of a 2D slab model takking account both tearing and interchange instabilities, theoretical and numerical linear studies show the pressure effect on the magnetic island linear formation and show interchange modes are stabilized in presence of a strong magnetic field. Then, a numerical nonlinear study is presented in order to understand how the interchange mechanism affects the nonlinear dynamics of a magnetic island. It is showned that the pressure gradient and the magnetic field curvature affect strongly the nonlinear evolution of a magnetic island through dynamics bifurcations. The nature of these bifurcations should be characterized in fonction of the linear situation. Finally, the last part of this phd is devoted to the study of the origin of the nonlinear poloidal rotation of the magnetic island. A model giving the different contributions to the rotation is derived. It is showned, thanks to the model and to the numerical studies, that the nonlinear rotation of the island is mainly governed by the E x B poloidal ow and/or by the nonlinear diamagnetic drift.
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Contributor : Magali Muraglia <>
Submitted on : Thursday, March 17, 2011 - 6:21:43 PM
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Magali Muraglia. Modélisation et simulation de l'interaction multi-échelles entre îlots magnétiques et la microturbulence dans les plasmas de fusion magnétisés. Physique [physics]. Université de Provence - Aix-Marseille I, 2009. Français. ⟨tel-00577937⟩

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