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Doctoral Thesis
DOI
10.11606/T.43.2007.tde-01042008-143757
Document
Author
Full name
Francisco Alberto Marcus
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2007
Supervisor
Committee
Caldas, Ibere Luiz (President)
Andrade, Maria Celia Ramos de
Kuznetsov, Yurii
Vannucci, Alvaro
Ziebell, Luiz Fernando
Title in Portuguese
Transporte de partículas induzido por ondas de deriva
Keywords in Portuguese
Caos
Física de plasma
Abstract in Portuguese
Nesta tese, investigamos o transporte caótico de partículas por ondas de deriva ressonantes na borda do plasma em tokamaks com fluxo poloidal de deriva do tipo ~E × ~B, um problema crítico para compreender, na fusão, as propriedades de confinamento dos plasmas. Usamos, para tokamaks com grande razão de aspecto, um modelo hamiltoniano não integrável (proposto por Horton) para descrever a contribuição dinâmica não linear ao transporte. Assim, embora o fluxo total, composto pelo fluxo de equilíbrio e por duas ondas de deriva ressonantes, não seja turbulento na descrição euleriana, as trajetórias lagrangianas das partículas são caóticas. Foi estudada a influência do perfil radial do campo elétrico nas barreiras de transporte e nas células convectivas criadas pela interação não linear entre o fluxo de equilíbrio e as ondas ressonantes. Para equilíbrios com fluxo reverso, nossos resultados mostram que o transporte de partículas pode ser reduzido pela alteração do perfil do campo elétrico. Finalmente, nossos resultados são aplicados para propor uma interpretação das experiências recentes em tokamaks que mostram uma redução do transporte quando um eletrodo polarizado é inserido na borda do plasma. Como um exemplo, usamos valores experimentais obtidos no TCABR para os perfis radiais do campo elétrico de equilíbrio e suas flutuações, durante o regime ôhmico padrão e durante o regime de confinamento melhorado.
Title in English
Particle transport induced by drift waves
Keywords in English
Chaos
Plasma physics
Abstract in English
We investigate the chaotic particle transport by resonant drift waves propagating in tokamaks plasma edges with ~E × ~B poloidal zonal flow, a critical problem for the understanding of the confinement properties of fusion plasmas. We assume, for large aspect ratio tokamaks, a non integrable hamiltonian model (proposed by Horton) to describe the non linear dynamical contribution to the transport. Thus, although the total flow, formed by the equilibrium flow and two dominant resonant drift waves, is not turbulent in the eulerian point of view, the lagrangian particle trajectories are chaotic. We study the influence of the electric field radial profile on the transport barriers and convective cells created by the non linear interaction between the poloidal flow and the resonant waves. For equilibria with reverse shear flows, our results show that the particle transport can be reduced by modifying the electric field profile. Futhermore, our results are applied to propose an interpretation of recent tokamak experiments developed for studying the transport reduction when a biased electrode is inserted into the plasma edge or the Scrape-Off-Layer. As an example, we use the equilibrium and fluctuating electric field radial profiles measured in the TCABR tokamak to calculate the transport during the standard ohmic and improved confinement regimes obtained in this tokamak.
 
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1640440.pdf (12.14 Mbytes)
Publishing Date
2008-04-09
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • KROETZ, T., et al. Transport control in fusion plasmas by changing electric and magnetic field spatial profiles [doi:10.1016/j.cpc.2008.12.025]. Computer Physics Communications [online], 2009, vol. 180, p. 642-650.
  • MARCUS, Francisco Alberto, et al. Chaotic transport in reversed shear tokamaks [doi:10.1088/0029-5515/48/2/024018]. Nuclear Fusion [online], 2008, vol. 48, p. 024018.
  • MARCUS, Francisco Alberto, et al. Reduction of chaotic particle transport driven by drift waves in sheared flows [doi:10.1063/1.3009532]. Physics of Plasmas [online], 2008, vol. 15, p. 112304.
All rights of the thesis/dissertation are from the authors
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