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Transport and Turbulence in Plasmas


Transport barriers of magnetic field lines play an important role in tokamak plasmas. Through devices that cause external perturbations, which may be an ergodic limiter, which disturbs rational surfaces at the edge of the plasma column, it is possible to produce a chaotic layer. Using a Hamiltonian formulation, we investigate the escape of the magnetic field lines towards the walls of the tokamak using an ergodic limiter to produce the resonant perturbations. The methodology used is similar to our previous papers to include the effects of plasma response in the presence of resonant magnetic perturbations. We present an analytical and numerical model to calculate the spatial distribution of the magnetic field when an electric current is applied in certain surfaces to simulate the plasma response to perturbative fields. The total magnetic field configuration resulting from this model is analyzed by means of Poincaré maps inserting a resonant perturbation produced by helices around the tokamak. We use TCABR tokamak parameters. According to simulations performed in tokamaks such as DIII-D, the influence of the plasma response to different perturbation modes was verified. We propose to complement our results to evaluate the transport of the magnetic field lines for different perturbation modes and to verify the influence of the magnitude of the perturbation current. It is also proposed to study the turbulence caused by drift waves in fusion plasmas following a numerical model explored in our previous works. It is proposed to analyze the changes of the phase space in the presence of a parallel velocity profile, using the tokamak TCABR data. The influence of the electric field profile on the shearless barriers will be verified. An analysis of the diffusion of particles will be analyzed later.Concerning my contribution to the Capes / Cofecub program, it is proposed to investigate the wave-particle interaction to control chaos. We will follow a methodology using a Hamiltonian that includes the relativistic wave-particle interaction interacting with electrostatic and stationary plane waves propagating in a direction perpendicular to the magnetic field. The map that describes the temporal evolution of the system will be analyzed by varying the perturbation parameter. The work will be done in collaboration with the IFUSP Control and Oscillations group. (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)
OSORIO, L. A.; ROBERTO, M.; CALDAS, I. L.; VIANA, R. L.; ELSKENS, Y.. Onset of internal transport barriers in tokamaks. Physics of Plasmas, v. 28, n. 8, . (18/14435-2, 18/03211-6, 20/01399-8)

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