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Master's Dissertation
DOI
10.11606/D.43.2002.tde-02082013-153147
Document
Author
Full name
Francisco Alberto Marcus
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2002
Supervisor
Committee
Caldas, Ibere Luiz (President)
Andrade, Maria Celia Ramos de
Vannucci, Alvaro
Title in Portuguese
Instabilidade dinâmica das flutuações eletrostáticas em tokamaks
Keywords in Portuguese
Descarga elétrica
Física de plasmas
Sistemas hamiltonianos
Tokamaks
Abstract in Portuguese
Neste trabalho foi realizado um estudo do transporte de partículas em um plasma, confinado em um campo magnético uniforme, devido às ondas eletrostáticas de deriva. O modelo adotado consiste em descrever o movimento do centro de guia de uma partícula no campo magnético perpendicular a um campo elétrico radial perturbado pelas ondas de deriva. Usamos uma descrição Hamiltoniana para o movimento dos centros de guia. A velocidade de deriva produzida pelo campo elétrico radial é representada pela parte integrável da Hamiltoniana e a esta foram adicionadas perturbações periódicas representando as flutuações do campo elétrico associadas às ondas de deriva. Assim, obtemos órbitas caóticas que determinam o transporte radial das partículas. Apresentamos, para várias condições de equilíbrio, a variação do transporte radial de partículas com a amplitude da perturbação. Utilizamos dados experimentais, sobre a turbulência eletrostática no tokamak TBR-1, para verificar a validade do modelo e a importância das ondas de deriva no transporte radial das partículas. Comparamos os valores do coeficiente de difusão experimental com os do modelo e obtivemos os resultados com a mesma ordem de grandeza.
Title in English
Dynamic Instability of Fluctuations Electrostatic in tokamaks
Keywords in English
Electric discharge
Hamiltonian systems
Physics of plasmas
Tokamaks
Abstract in English
In this work we have studied the transport of particles in a magnetically confined plasma, due to electrostatic drift waves. The adopted model 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 orbits that determine the particles radial transport. For several balance conditions, we present the variation of the radial transport of particles with the amplitude of the perturbation. V/e have used the experimental data of the 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.
 
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35836MARCUS.pdf (4.39 Mbytes)
Publishing Date
2013-08-06
 
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