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Transport of magnetic field lines and particles in tokamaks


Magnetic field line transport barriers have an important role in controlled fusion in tokamaks. Through devices that cause external perturbations, which may be an ergodic limiter, rational surfaces can be destroyed at the edge of the plasma column. In this way it is possible to have a stochastic layer. With a non monotonic safety factor profile it is possible to obtain the formation of an internal transport barrier that hampers the transport of field lines. A Hamiltonian formulation was used to study field line perturbed by an ergodic limiter to produce the resonant perturbations [1,11]. In this project we will continue to study the effects of transport barriers as has started in recent studies [12,13,14] called robusto toro [12,13,14] and labyrintic [15,16], which may influence the transport of magnetic field lines toward the walls of the tokamak. It is also proposed to build a model for the magnetic field line in tokamaks having a point X (hyperbolic) on the outside of the plasma, simulating a divertor. For that will be used a configuration of infinite wires arranged in such a way as to generate a X point. Preliminary results are published in reference [17]. Disturbances created by "error fields [18,19] near the point X will be introduced in the model to study the escape patterns and the magnetic field lines near the hyperbolic point. Furthermore we intend to continue the study of the conservative map for MHD equilibrium, which presents a X point, following the method presented by Morrison Abbamonte [20]. The advantage of using this map lies in the fact that we can choose a safety factor profile related to a realistic magnetic configuration. We apply this methodology to a circular section tokamak including resonant perturbations. The results are published in reference [21]. It is intended to continue this work by investigating the transport of magnetic field lines with cross-section that includes elongation, such as those occurring in tokamks as ITER [22]. It will also be added to map a term that allows the study particle transport [23,24]. And finally we propose to investigate the particle transport in tokamaks by means of computer simulation using the code Kronos [25]. I was in Cadarache, France, in April-May 2010, making a training program to obtain a license to use the code, so as to obtain the software. We intend to investigate the MHD equilibrium using a current reversed toroidal profile by analytical solution of the Grad-Shafranov equation and by Cronos. This profile produces magnetic islands near the magnetic axis [26]. We intend to investigate the influence of these islands on the transport phenomena. (AU)

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(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
DE OLIVEIRA, LUIS C.; MARTINS, CAROLINE G. L.; ROBERTO, M.; CALDAS, I. L.; EGYDIO DE CARVALHO, R.. Robust tori-like Lagrangian coherent structures. PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS, v. 391, n. 24, p. 6611-6616, . (10/20276-2, 10/16666-0)

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