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It became clear in the early days of fusion research that the effects of the containment vessel (erosion of "impurities") degrade the overall fusion plasma performance. Progress in controlled nuclear fusion research over the last decade has led to magnetically confined plasmas that, in turn, are sufficiently powerful to damage the vessel structures over its lifetime. This book reviews current understanding and concepts to deal with this remaining critical design issue for fusion reactors. It reviews both progress and open questions, largely in terms of available and sought-after plasma-surface interaction data and atomic/molecular data related to these "plasma edge" issues.
Nuclear fusion --- Plasma (Ionized gases) --- Nuclear reactions --- Research --- Fusion, Nuclear --- Fusion reactions --- Fusion --- Nuclear fusion. --- Surfaces (Physics). --- Nuclear Fusion. --- Nuclear Energy. --- Atoms and Molecules in Strong Fields, Laser Matter Interaction. --- Plasma Physics. --- Surfaces and Interfaces, Thin Films. --- Physics --- Surface chemistry --- Surfaces (Technology) --- Monograph --- Nuclear energy. --- Atoms. --- Physics. --- Plasma (Ionized gases). --- Materials—Surfaces. --- Thin films. --- Films, Thin --- Solid film --- Solid state electronics --- Solids --- Coatings --- Thick films --- Gaseous discharge --- Gaseous plasma --- Magnetoplasma --- Ionized gases --- Natural philosophy --- Philosophy, Natural --- Physical sciences --- Dynamics --- Chemistry, Physical and theoretical --- Matter --- Stereochemistry --- Atomic energy --- Atomic power --- Energy, Atomic --- Energy, Nuclear --- Nuclear power --- Power, Atomic --- Power, Nuclear --- Force and energy --- Nuclear physics --- Power resources --- Nuclear engineering --- Nuclear facilities --- Nuclear power plants --- Constitution --- Nuclear fusion research
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Plasma physics --- Nuclear physics --- Atomic physics --- Solid state physics --- Nuclear energy --- kernfusie (technologie) --- plasmafysica --- kernenergie --- fysica
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It became clear in the early days of fusion research that the effects of the containment vessel (erosion of "impurities") degrade the overall fusion plasma performance. Progress in controlled nuclear fusion research over the last decade has led to magnetically confined plasmas that, in turn, are sufficiently powerful to damage the vessel structures over its lifetime. This book reviews current understanding and concepts to deal with this remaining critical design issue for fusion reactors. It reviews both progress and open questions, largely in terms of available and sought-after plasma-surface interaction data and atomic/molecular data related to these "plasma edge" issues.
Plasma physics --- Nuclear physics --- Atomic physics --- Solid state physics --- Nuclear energy --- kernfusie (technologie) --- plasmafysica --- kernenergie --- fysica
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High-performance helium exhaust is one of the primary design criteria for the divertor in nuclear fusion reactors. Helium particles - which are produced as the main reaction product - need to be removed from the fusion plasma to avoid dilution of the hydrogenic fuel. In recent years, efficient automated optimization techniques have been developed to assist in the divertor design. This thesis aims to take the first steps towards extending these techniques to the helium exhaust issue. Because of its exploratory approach, the emphasis of this thesis lies on the theoretical foundation, implementation and numerical verification of the relevant methods. The efforts are directed towards a simplified test case which forms the central theme throughout the report. The test case comprises a slab representation of the plasma edge where the particle transport is governed by a kinetic model. A basic optimization problem, seeking to optimize the helium pump placement, is linked to the test case model. In the first step, a forward Monte Carlo procedure for the solution of the test case is determined. After showing why the kinetic model can be solved with Monte Carlo techniques, a non-analog Monte Carlo game is defined and implemented. The forward Monte Carlo algorithm is successfully verified by comparing its results to analytical solutions for different problems. In particular, the analogy between radiation and particle transport is exploited to find a closed-form solution for diffuse particle transfer in a toroidal geometry. Adjoint Monte Carlo is investigated as an alternative to the forward approach since it is known to have efficiency benefits in certain geometries. Again, the method is first treated formally, starting from the earlier discussion of the forward variant. Based on the literature, a practical adjoint algorithm for solving the test case is derived. Numerical verification shows excellent correspondence between forward and adjoint procedures in a variety of situations including the test case. The adjoint differentiation technique is the centrepiece of optimization methods for divertor design, because its computational cost is independent of the number of design variables. In conclusion of the thesis, this technique is applied to the test case model. It is shown in the derivation of the adjoint equations that the adjoint Monte Carlo procedure can be used to find the necessary adjuncton fluxes. When complemented with a forward Monte Carlo simulation, the adjoint procedure allows calculation of the test case sensitivities. The comparison to a finite differences approximation is attempted to verify this calculation. The method performs adequately given the assumptions, and further refinements are still possible.
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