TITLE
	Chaotic Transport Induced by Electrostatic Fluctuations in Tokamaks
	
AUTHOR
	Ibere CALDAS

ABSTRACT 
	Improvement of plasma confinement in tokamaks depends on plasma edge behavior. Experiments 
	indicate that this behavior depends on the anomalous particle transport caused by the 
	observed electrostatic turbulence. Thus, it is important to estimate the importance of 
	chaotic particle orbits on this transport. To do that, in this work we have studied the 
	transport of particles in a magnetically confined plasma,due to electrostatic drift waves. 
	The adopted model (proposed by W. Horton) describes the trajectory of the guiding center 
	of a particle in a uniform magnetic field perpendicular to a radial electric field 
	perturbed by drift waves. We have used the Hamiltonian description for the guiding center 
	trajectory. The drift produced by the radial electric field is represented by the 
	integrable part of the Hamiltonian, while the other part contains periodic perturbations 
	representing the fluctuations of the electric field associated to the drift waves. In this 
	way we obtain chaotic o  rbits that determine the particles radial transport. For several 
	balance conditions, we present the variation of the radial transport of particleswith the 
	amplitude of the perturbation. We have used the experimental data of electrostatic 
	turbulence measured in TBR-1 tokamak to verify the validity of the model and the importance 
	of the drift waves in the particles radial transport. We have also compared the values of 
	the experimental diffusion coefficient with those provided by using the model, obtaining 
	results with the same order of magnitude.