Benoît Labit

Expertise H-mode physicsPlasma turbulenceExperimental physicsNumerical simulations Current work Deputy Task Force Leader for the EUROfusion Workpackage "Tokamak Exploitation" PhD Thesis Tokamak electron heat transport by direct numerical simulation of small scale turbulenceIn a fusion machine, understanding plasma turbulence, which causes a degradation of the measured energy confinement time, would constitute a major progress in this field. In tokamaks, the measured ion and electron thermal conductivities are of comparable magnitude. The possible sources of turbulence are the temperature and density gradients occurring in a fusion plasma. Whereas the heat losses in the ion channel are reasonably well understood, the origin of the electron losses is more uncertain. In addition to the the radial velocity associated to the fluctuations of the electric field, electrons are more affected than ions by the magnetic field fluctuations. In experiments, the confinement time can be conveniently expressed in terms of dimensionless parameters. Although still somewhat too imprecise, these scaling laws exhibit strong dependencies on the normalized pressure, β or the normalized Larmor radius, ρ*.The present thesis assesses whether a tridimensional, electromagnetic, nonlinear fluid model of plasma turbulence driven by a specific instability can reproduce the dependence of the experimental electron heat losses on the dimensionless parameters β and ρ*. The investigated interchange instability is the Electron Temperature Gradient driven one (ETG). The model is built by using the set of Braginskii equations. The developed simulation code is global in the sense that a fixed heat flux is imposed at the inner boundary, leaving the gradients free to evolve.From the nonlinear simulations, we have put in light three characteristics for the ETG turbulence: the turbulent transport is essentially electrostatic; the potential and pressure fluctuations form radially elongated cells called streamers; the transport level is very low compared to the experimental values.The thermal transport dependence study has shown a very small role of the normalized pressure, which is in contradiction with the Ohkawa Education Docteur es Sciences | mention Rayonnement et Plasmas 2002 – 2002 Universit� de Provence Aix-Marseille I Directed by Dr. M. Ottaviani et Dr. D. F. Escande Professionals experiences Collaborateur scientifique 2009–2009 EPFLPost-doc 2003–2008 EPFLDoctorant 1999–2002 CEA Cadarache (F) Teaching & PhD PhD Students Martino Bonisolli, Haoran Zhang, Mackenzie Peter-Fulford Van Rossem Past EPFL PhD Students as codirector Federico Nespoli Courses Plasma Diagnostics in Basic Plasma Physics Devices and Tokamaks: from Principles to Practice PHYS-732 The programme will allow students to learn plasma diagnostics and data processing methods of modern fusion experiments and to bridge the gap between diagnostics theory and experimental practice. Master and TP projects Lucia Federspiel Alexandre Bovet Boris Roulet Fabio Riva Francesca Capel (Erasmus Imperial College) Richard Flint (Erasmus Imperial College)