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AbstractAbstract
[en] Magnetic confinement fusion is currently the most advanced way to produce energy thanks to Deuterium/Tritium reaction. One of the challenges is the limitation of the reaction contamination because of Tungsten (W), a material capable of resisting high heat fluxes. W large atomic number causes W to radiate inside tokamak plasmas. If W accumulates in the central part, it cools down the plasma. It is therefore crucial to understand the mechanisms of W transport and identify the actuators of the accumulation process. W transport is involved in complex interplays with the plasma parameters (density, temperature, rotation). Therefore the use of integrated modeling is mandatory in order to evolve self-consistently all those parameters for several confinement times. For the first time, an integrated modeling tool is coupled to first-principle transport codes to self-consistently simulate the time evolution of the W behavior, as well as the evolution of density, temperature, rotation profiles, radiation and external heating. For numerical reasons, several phenomena are not modeled, and the physics of the interaction with the inner wall is simplified. At each time step, this simulation successfully reproduces experimental profiles and the W central accumulation. Moreover, actuators of the central W accumulation (rotation and central particle fueling) were identified. Finally, integrated modeling simulation allowed bringing out a very interesting non-linear mechanism: the stabilizing effect of W on turbulence. This work demonstrates that first-principles integrated modeling now allows to design and optimize in advance plasma scenarios with limited W central accumulation. (author)
[fr]
La fusion par confinement magnetique est actuellement la voie la plus avancee pour produire de l'energie grace a la reaction de fusion. L'un des defis a relever concerne la contamination du plasma par le Tungstene (W), un materiau capable de resister aux hauts flux de chaleur. A cause de son grand nombre atomique, le W rayonne dans les plasmas de tokamak. S'il s'accumule au coeur du tokamak, il refroidit le plasma. Il est donc crucial de comprendre les mecanismes du transport du W et d'identifier les parametres favorisant son accumulation. Le W interagit de facon non-lineaire avec les differents parametres du plasma. La simulation integree est le seul outil permettant a tous ces parametres d'etre simules de facon auto-consistante durant plusieurs temps de confinement. Pour la premiere fois, l'outil de simulation integree est couple a des codes de transport premiers principes modelisant de facon auto-consistante les transports turbulent et collisionnel du W, les profils de densite, temperature, rotation, radiation, et l'evolution du chauffage. Pour des raisons numeriques, certains phenomenes ne sont pas modelises et l'interaction plasma/paroi interne est simplifiee. A chaque pas de temps, cette simulation reproduit avec succes les signaux experimentaux et le comportement du W. De plus, des acteurs responsables de l'accumulation du W (la rotation et la source centrale de particules) sont identifies. Enfin, la simulation integree a permis de mettre en lumiere l'effet stabilisant du W sur la turbulence. Le travail accompli montre que la simulation integree premiers principes permet desormais d'optimiser a l'avance les scenarios de plasma afin d'y limiter l'accumulation de W.Original Title
Transport du tungstene dans un tokamak par une modelisation integree premiers principes
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12 Jan 2018; 131 p; 141 refs.; Available from the INIS Liaison Officer for France, see the INIS website for current contact and E-mail addresses; Physique et Sciences de la Matiere
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Report
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Thesis/Dissertation
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