Dissertationen zum Thema „Plasma du borde“
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Scotto, d'Abusco Manuel. „Modélisation numérique du transport turbulent cœur-bord dans un tokamak en géométrie réaliste par une méthode numérique avancée“. Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0173.
Der volle Inhalt der QuelleNowadays a challenge remains the design of optimized plasma scenarios for tokamak operation to control the heat flow from the core region to the wall. This calls for the development of efficient and reliable numerical codes with predictive capabilities for plasma simulations. The present work aims to develop a high-order finite elements code based on hybrid discontinuous Galerkin numerical scheme and an efficient implicit time integration method for solving non isothermal Braginskii reduced fluid equations in versatile tokamak and magnetic equilibrium geometries. The use of such numerical scheme allows to perform simulations with time evolving magnetic configurations, avoiding expensive re-meshing of the computational domain. The structure and the realization of such a numerical tool is presented. The feasibility of the latter is then investigated through a careful validation and benchmarking operation with SolEdge3X. Self-consistent sources of particle, due to plasma recycling, and energy due to Ohmic heating are introduced to perform 2D simulation of a full poloidal tokamak cross section. With such a model the main features of a detached plasma are investigated for the WEST tokamak machine. The first core-edge transport simulations of an entire WEST discharge (shot #54487) are shown from the start-up phase to the final plasma landing. Comparisons between experimental interferometry and synthetic simulation data show a remarkable agreement. The time evolution of the particles and heat fluxes at the wall, are analyzed and exploited to assess the tungsten sputtering, using both a simple cinematic model and the impurity tracker monte-carlo code ERO2.0
Sugita, Satoru. „Etude par simulation numérique du transport radial dans le plasma de bord du tokamak“. Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10010/document.
Der volle Inhalt der QuelleRecently, it has been accepted that magnetic field aligned plasma filaments, referred to as "blobs" play important roles in the transport of Scrape-off Layer (SoL) plasmas. In this thesis, putting an emphasis on the plasma blob phenomenon, we study fundamental processes of SoL transport using numerical simulation. At first, weinvestigate the propagation mechanisms of single and isolated blobs.Next, we study the generation of blobs from edge turbulence, and discuss the SoL turbulent transport as a collective phenomenon. Features of turbulent transport, which includes the self-organized blobs in SoL, are identified as Bohm-like transport (i.e., the perturbation with long radial correlations and the effective transport coefficient that follows the dependence of Bohm-like transport). Additionally, as an advancement of study, we describe an initial effort to extend the view of non local transport to edge plasmas
Medvedeva, Anna. „Étude expérimentale de la turbulence au bord du plasma du tokamak ASDEX Upgrade par réflectométrie à balayage ultra rapide“. Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0240/document.
Der volle Inhalt der QuellePlasma confinement is limited by energy and particle transport, in which turbulence plays an important role. In this work the measurements of the turbulence characteristics carried out on the ASDEX Upgrade tokamak are presented during the transition from the Low (L) to the High (H) confinement mode which goes through an Intermediate (I) phase where turbulence and shear flows strongly interact. One of the most widely accepted theories concerning the L-H transition describes how the turbulence in the plasma edge is stabilized by radial electric field gradients: the E×B flow shear stabilizes turbulence and decreases the radial size of turbulent structures. As a consequence, a transport barrier forms in the edge where the plasma density, the temperature, and their gradients increase. The detailed physical mechanism of the formation of the transport barrier as well as the reason for the residual transport across this barrier are not yet well understood. The density dynamics is measured by an ultra-fast swept reflectometer with a time resolution as high as 1 μs. Studies of the electron density profile dynamics, the density turbulence level, radial wavenumber and frequency spectra during L-H transitions have been performed. The reflectometer measurements show that the density large scale fluctuations decrease after an L-H transition, which confirms the theoretical predictions of the turbulence reduction by sheared flows and supports previous experimental evidences. I-phases for various plasma conditions are documented and the density evolution is compared with the turbulence level. Moreover the results on high frequency coherent modes appearing at the plasma edge are presented
Touati, Ahmed Kamel. „Analyse spectroscopique des plasmas en présence d'un champ magnétique : application au plasma de bord des tokamaks“. Aix-Marseille 1, 2003. http://www.theses.fr/2003AIX11004.
Der volle Inhalt der QuelleJanisson, Stéphane. „Etude des jets de plasma et du traitement des particules en projection plasma avec mélanges ternaires de gaz en atmosphère et température contrôlées“. Limoges, 1999. http://www.theses.fr/1999LIMO0046.
Der volle Inhalt der QuelleThis work deals with the use of ternary gas mixtures Ar-He-H2 for plasma spraying, in controlled atmosphere and temperature. These ternary gas mixtures were used to spray boron carbide powder in argon atmosphere at ambient pressure. The various sub-systems that make up the whole plasma spraying process have been studied : (i) plasma jet formation in the anode-nozzle, (ii) plasma flow outside the gun, (iii) plasma/particle interactions and (iv) coating formation. .
Tazedakis, A. S. „Orbital plasma welding of small bore tubes“. Thesis, Cranfield University, 1997. http://dspace.lib.cranfield.ac.uk/handle/1826/10436.
Der volle Inhalt der QuelleTazedakis, Athanassios S. „Orbital plasma welding of small bore tubes“. Thesis, Cranfield University, 1997. http://dspace.lib.cranfield.ac.uk/handle/1826/10436.
Der volle Inhalt der QuelleMalhouitre, Stéphane. „Etude et réalisation de couches minces de nitrure de bore par dépôt ionique réactif“. Limoges, 1997. http://www.theses.fr/1997LIMO0010.
Der volle Inhalt der QuelleTorres, Israel da Silva. „Magnetoplasmons de borda em sistemas bidimensionais: estudo do Helicon de Borda“. Universidade Federal do Amazonas, 2012. http://tede.ufam.edu.br/handle/tede/4542.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
In this work we will make a theoretical investigation over some general properties of edge magnetoplasmos (EMP) - collective quiral excitations which propagates at the edges of a bidimensional solid state plasma (often called bidimensional electronic system- 2DES) under the quantum Hall regime (QHR) with lling factor of = 1(2),with very strong dissipation in the edges, where the Landau levels (LL) intercept the Fermi levels (FL). We will take into account only homogenuous samples, that means, without a consideration of a gate nor an air substrate over the heterostructure; pointed out that the EMP behaviour, especially the wave quality, has a strong dependence on the gate. EMP s were rst reported in the 80 s, and have attracted much attention in the past decade with advent of some new nano-2DES, new experimental methods - as the time- resolved experiments, and nano electronic aplications. Adopting a microscopic model, we could con rm recent works (2010), and we con rmed that even in the strong dissipation regime, here considered, there is still a mode that persists, an edge helicon (EH), with excelent quality - when all other modes are very damped. We also nd new interesting properties of this EH, in fact, we can show that the "window of transparency" of this EH is 10 times bigger then the value so far known from the scienti c literature, its spatial structure was also here accquired with better precision; and it exibits a more smooth behavior if compared to recent articles.
Neste trabalho faremos um estudo teórico acerca de propriedades dos magneto-plasmons de borda (MPB) excitações quirais coletivas e que se propagam nas bordas de um plasma de estado sólido bidimensional (comumente cunhado como um sistema eletrônico bidimensional - SE2D) - sob o regime Hall quântico inteiro (RHQI) com fator de preenchimento = 1(2) e com muito-forte dissipação nas regiões de estados de borda, onde os níveis de Landau (NL) cruzam o nível de Fermi (NF). Serão considerados neste trabalho apenas amostras homogêneas, ou seja, sem a consideração de um gate ou uma camada de ar sobre a heteroestrutura; cujo comportamento dos MPB s, especialmente a qualidade do MPB, tem forte vínculo com propriedades do meio em questão. Os primeiros MPB s foram descobertos na década de 1980, e têm despertado um grande interesse na última década, com o advento de novas nanoestruturas eletrônicas bidimensionais, novos métodos experimentais - como por exemplo os experimentos com tempo-resolvido (time-resolved) e aplicacões diretas em nanoeletrônica. Adotando-se um modelo miscroscópico, pudemos con firmar resultados de trabalhos recentes (2010), e confi rmamos que mesmo no regime de muito-forte dissipação, aqui considerado, ainda há um modo que persiste, um Helicon de Borda (HB), com excelente qualidade - enquanto que todos os outros mo- dos são fortemente amortecidos. Encontramos também novas interessantes propriedades deste HB, em particular, mostramos que "janela de transparência" deste HB é 10 vezes maior do que o valor conhecido na literatura, a estrutura espacial do HB também foi aqui obtida com melhor precisão; e exibe um comportamento mais suave que o apresentado em trabalhos recentes.
Sarazin, Yanick. „Etude de la turbulence de bord dans les plasmas de tokamaks“. Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10265.
Der volle Inhalt der QuelleLaribi, Elias. „Modélisation numérique de l'impact de la géométrie magnétique sur le plasma de bord des tokamaks“. Electronic Thesis or Diss., Aix-Marseille, 2021. http://www.theses.fr/2021AIXM0298.
Der volle Inhalt der QuelleThis phD work has shown that, in a limiter configuration, the elongation of magnetic surfaces has a stabilizing effect with respect to the edge plasma turbulence. This leads to a reduction of the edge plasma width when the elongation increases. Regarding triangularity, this phD work revealed that its effects on the edge plasma were weaker than those of elongation. A better understanding of these trends has been possible thanks to a theoretical work on a simplified interchange model. This work has also revealed the importance of the magnetic field spatial variability on the poloidal size of turbulent structures and therefore on the radial turbulent fluxes. In a second step, the study of a divertor configuration with one X point has shown that the the magnetic field spatial variability was so important that it could be one of the reasons that explain the enhancement of the low field side ballooned nature of edge plasma turbulence in a divertor geometry. Still concerning the divertor geometry, this phD also revealed that the internal material receives more heat compared to the external material when the toroidal magnetic field is oriented in the direct direction (= magnetic drift of the ions pointing towards the X point). A possible explanation of this observation is the existence of a significant plasma circulation from the low field side to the high field side at the X point that we observed in this configuration. Finally, we were able to confirm that one way to improve this heat flux distribution on the walls was to merge two X points perfectly (= ideal snowflake proposed in 2007 by Ryutov and Sukhanovsky)
Rayar, Marius. „Dépôt assisté par plasma micro-onde de films diamants dopés au bore : procédé et diagnostics“. Lille 1, 2006. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2006/50376_2006_104.pdf.
Der volle Inhalt der QuelleIsoardi, Livia. „Modelisation du transport dans le plasma de bord d'un tokamak“. Aix-Marseille 3, 2010. http://www.theses.fr/2010AIX30066.
Der volle Inhalt der QuelleFedorczak, Nicolas. „Etude expérimentale de transport turbulent au bord d'un plasma de tokamak“. Phd thesis, Université de Provence - Aix-Marseille I, 2010. http://tel.archives-ouvertes.fr/tel-00627522.
Der volle Inhalt der QuelleRosato, Joël. „Modélisation en spectroscopie et application au plasma de bord des tokamaks“. Aix-Marseille 1, 2007. http://theses.univ-amu.fr.lama.univ-amu.fr/2007AIX11025.pdf.
Der volle Inhalt der QuelleThis thesis brings theoretical results on spectroscopy of hydrogen and gives some applications to tokamak edge plasmas. Miscellaneous line broadening models are developed and applied in three ways: diagnostic of plasma parameters, diagnostic of turbulent fluctuations of the plasma, and opacity studies. A review is first made (Chap. 1) on physical mechanisms which contribute to line broadening, such as for example motion of the emitters (Doppler effect) or electric field of the plasma (Stark effect). An analytical model is developed (Chap. 2) for opacity of Lyman a line (transition 2 → 1); this model, which takes into account Doppler effect, Zeeman effect, Stark effect and fine structure, has been incorporated into a transport code for studies of radiative transfer in ITER edge plasma. A refinement of Stark broadening description is next made (Chap. 3), in order to take into account quadratic Stark effect induced by the Zeeman degeneracy removal of atomic levels. The model is validated by a numerical simulation method. Finally, a study is presented (Chap. 4) on line broadening in presence of turbulence. It is shown how a line profile is related to the probability density function (PDF) of fluid fields; an application of formalism is then made to describe Doppler broadening of Da line (transition 3 → 2 of deuterium) and Stark broadening of D10 line (transition 10 → 2). Consequences for diagnostic interpretation are discussed
Galassi, Davide. „Numerical modelling of transport and turbulence in tokamak edge plasma with divertor configuration“. Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0632/document.
Der volle Inhalt der QuelleNuclear fusion could offer a new source of stable, non-CO2 emitting energy. Today, tokamaks offer the best performance by confining a high temperature plasma by means of a magnetic field. Two of the major technological challenges for the operation of tokamaks are the power extraction and the confinement of plasma over long periods. These issues are associated with the transport of particles and heat, which is determined by turbulence, from the central plasma to the edge zone. In this thesis, we model turbulence in the edge plasma. We study in particular the divertor configuration, in which the central plasma is isolated from the walls by means of an additional magnetic field. This complex magnetic geometry is simulated with the fluid turbulence code TOKAM3X, developed in collaboration between the IRFM at CEA and the M2P2 laboratory of the University of Aix-Marseille.A comparison with simulations in simplified geometry shows a similar intermittent nature of turbulence. Nevertheless, the amplitude of the fluctuations, which has a maximum at the equatorial plane, is greatly reduced near the X-point, where the field lines become purely toroidal, in agreement with the recent experimental data. The simulations in divertor configuration show a significantly higher confinement than in circular geometry. A partial inhibition of the radial transport of particles at the X-point contributes to this improvement. This mechanism is potentially important for understanding the transition from low confinement mode to high confinement mode, the intended operational mode for ITER
Leybros, Robin. „Etude des vitesses de dérive fluides dans le plasma de bord des tokamaks : modélisation numérique et comparaison simulation/expérience“. Thesis, Ecole centrale de Marseille, 2015. http://www.theses.fr/2015ECDM0006/document.
Der volle Inhalt der QuelleThe transport of heat and particles in the edge of tokamaks plays a key role in both the performance of the confined plasma and the extraction of power and thus the lifetime of the plasma facing components. It’s in this context that this thesis is inscribed, which focuses on the role played by the transverse magnetic field flows in the balance between parallel and perpendicular dynamic that governs the edge region of a tokamak. These flows can produce poloidal asymmetries of heat and particles deposit on plasma facing components and generally asymmetries of various amounts in plasma. The radial drift velocities are due to the presence of a radial electric field resulting from charge balance (electric drift velocity) or related to effects of the toroidal geometry inducing a magnetic field inhomogeneity (curvature drift velocity). To advance the understanding of these phenomena, numerical modeling of transport and turbulence in complex geometries is essential. In addition, synthetic diagnostic tools for modeling the measurement process in numerical plasmas are developed to enable a realistic comparison between models and experiments. Modeling of perpendicular drift velocities was introduced into the SOLEDGE2D code describing the transport of the density, momentum and energy of a tokamak plasma. We first studied the impact of a prescribed electric field on plasma equilibrium to understand the mechanisms behind plasma asymmetries and study the establishment of parallel flows and asymmetry of the heat flux on plasma facing components. Then we implemented a self-consistent model solving the electric potential in SOLEDGE2D fluid equations to understand the equilibrium of the electric field and to study the effect of the magnetic configuration of the tokamak and the curvature drift velocity on it. In the second part of this thesis, a synthetic diagnosis modeling the experimental measurements of Doppler backscattering was developed and tested in order to be applied to simulations of 3D turbulent fluid code TOKAM3X. This diagnosis measures the perpendicular velocity of the plasma from the movement of the density fluctuations. It was used to compare the perpendicular velocity asymmetries observed experimentally to asymmetries measured in numericalsimulations
Salem, Rania. „Modélisation des plasmas micro-ondes utilisés pour le dépôt de diamant intrinsèque ou dopé au bore“. Thesis, Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCD013.
Der volle Inhalt der QuelleThis thesis deals with modelling of high power density microware plasmas of H2/CH4 and H2/CH4/B2H6 mixtures used for growing intrinsic and boron-doped diamond films. The aim of this work is to establish chemical kinetic schemes in order to describe the gas phase composition and to manage limitations of physical models of high power density H2/CH4 and H2/CH4/B2H6 plasmas. This investigation relies on a numerical approach using different physical models (ID and 2D) as well as chemical models according to differents experimental parameters (pressures, power, gas composition). Comparisons are carried out with integrated densities of CH4, CH3, C2H2, C2H4, C2H6, B2H6 and B measured by TDLAS and OES in order to validate the models. Significant discrepancies highlight limitation of ID approach for high power density whereas the use of a 2D fluid model (Fluent based) proposes better description of transport phenomena. The chemical analysis of H2/CH4, H2/B2H6 and H2/CH4/B2H6 MW plasmas also shows a limitation of the current kinetic schemes for a wide range of operating conditions. In particular C/B mechanisms do not reproduce the strong influence of methane addition on B. At least, a numerical study of spatial composition of boron species near the substrate is compared to experimental results on doping efficiency
Kaeppelin, Vincent. „Caractérisation d'une source de plasma hélicon et application à l'implantation ionique par immersion plasma“. Aix-Marseille 1, 2002. http://www.theses.fr/2002AIX11027.
Der volle Inhalt der QuelleElhenshir, Omar Said Ali. „Cold atmospheric plasma : studies on inactivation mechanisms in food-borne pathogens and laboratory strains“. Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/28391/.
Der volle Inhalt der QuelleFavia, Paola. „Le bore, du cristal à l'amorphe et ses réactions en présence d'un plasma /“. [S.l.] : [s.n.], 1997. http://library.epfl.ch/theses/?nr=1622.
Der volle Inhalt der QuelleBonnement, Audrey. „Modélisation numérique par approximation fluide du plasma de bord des tokamaks (projet ITER)“. Nice, 2012. http://www.theses.fr/2012NICE4088.
Der volle Inhalt der QuelleMagnetic confinement fusion allows to favour fusion reactions and energy production with toric devices, called tokamaks, using an electro-magnetic field in order to confine the plasma. To study the edge plasma of tokamak, we use a fluid model, obtained from the Vlasov-Maxwell kinetic model and the Braginskii closure. A finite volume/element method is chosen to approach the model. The system is similar to the Euler or anisotropic Navier-Stokes systems, with additional terms to model the plasma confinement. We propose some methods to approach these terms and to model Bohm boundary conditions, characteristic of tokamak. Moreover, a finite volume method in cylindrical coordinates is proposed in order to preserve the conservative form of the equations. Thus, we consider as elementary volume, the cell which is given by rotation around the tokamak axis of the 2D cell. Several numerical results are given, e. G. For an anisotropic diffusion problem with radiation and also for simulations of pellet injections (matter ice cubes) to refuel the tokamak
Luce, Benjamin. „Impact of 3D non axisymmetrical magnetic perturbations on the transport and turbulence in the edge plasma of tokamaks“. Electronic Thesis or Diss., Aix-Marseille, 2020. http://www.theses.fr/2020AIXM0602.
Der volle Inhalt der QuelleThe power exhaust and the increase of the confinement time are two major challenges for tokamaks. These are linked to the perpendicular, mostly turbulent transport toward the wall. The H-mode reduces the perpendicular transport but is associated with deleterious relaxation events, the ELMs, which lead to unreasonnable transient heat fluxes. In order to control the ELMs. 3D magnetic perturbations (MP) have been added. If some impacts of MPs have been studied, few data exist on their impact on the turbulent transport.In this thesis, we model the edge plasma, from the outer core to the Scrape-Off Layer (SOL), with a 3D electrostatic fluid turbulent code, TOKAM3X and a mean-field one, SOLEDGE3X_HDG. With the TOKAM3X, we observe the impact of 3D MPs on edge turbulence. We start with an electrostatic isothermal model with single mode MP in a limiter circular geometry. This study reproduces some experimental observations. The MPs only moderately impact turbulence properties. A complexification of the model is done, with non isothermal simulations. We show that the decoupling of particles and energy is important. Experimental trends are recovered. The impact on turbulence is still moderated. An analysis of the consequences of such findings for mean-field simulations is then proposed through a direct comparison. It shows a significant difference with turbulentsimulations. Finally, first results in the direction of more realistic MPs spectra are presented, using TOKAM3X mean-field cases as a start. An extension of this work is done on SOLEDGE3X_HDG in more complex geometries and even simulating a realistic ripple in WESTgeometry
Gallo, Alberto. „Impact of the plasma geometry on the divertor power exhaust in a magnetic fusion reactor“. Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0001/document.
Der volle Inhalt der QuelleA deep understanding of plasma transport at the edge of a magnetically confined fusion device is mandatory for a sustainable and controlled handling of the power exhaust. In the next-generation fusion device ITER, technological limits constrain the peak heat flux on the divertor. For a given exhaust power the peak heat flux is determined by the extent of the plasma footprint on the wall. Heat flux profiles at the divertor targets of X-point configurations can be parametrized by using two length scales for the transport of heat in SOL. In this work, we challenge the current interpretation of these two length scales by studying the impact of divertor geometry modifications on the heat exhaust. In particular, a significant broadening of the heat flux profiles at the outer divertor target is diagnosed while increasing the length of the outer divertor leg. Modelling efforts showed that diffusive simulations well reproduce the experimental heat flux profiles for short-legged plasmas. Conversely, the broadening of the heat flux for a long divertor leg is reproduced by a turbulent model, highlighting the importance of turbulent transport not only in the main SOL but also in the divertor. These results question the current interpretation of the heat flux width as a purely main SOL transport length scale. In fact, long divertor leg magnetic configurations highlighted the importance of asymmetric divertor transport. We therefore conclude that main SOL and divertor SOL transport cannot be arbitrarily disentangled and we underline the importance of the divertor magnetic geometry in enhancing asymmetric turbulent transport with the potential benefit of an unexpected power spreading
Kuhn, Matthieu. „Calcul parallèle et méthodes numériques pour la simulation de plasmas de bords“. Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAD023/document.
Der volle Inhalt der QuelleThe main goal of this work is to significantly reduce the computational cost of the scientific application Emedge3D, simulating the edge of tokamaks. Improvements to this code are made on two axes. First, innovations on numerical methods have been implemented. The advantage of semi-implicit time schemes are described. Their inconditional stability allows to consider larger timestep values, and hence to lower the number of temporal iteration required for a simulation. The benefits of a high order (time and space) are also presented. Second, solutions to the parallelization of the code are proposed. This study addresses the more general non linear advection-diffusion problem. The hot spots of the application have been sequentially optimized and parallelized with OpenMP. Then, a hybrid MPI OpenMP parallel algorithm for the memory bound part of the code is described and analyzed. Good scalings are observed up to 384 cores. This Ph. D. thesis is part of the interdisciplinary project ANR E2T2 (CEA/IRFM, University of Aix-Marseille/PIIM, University of Strasbourg/ICube)
Gallo, Alberto. „Impact of the plasma geometry on the divertor power exhaust in a magnetic fusion reactor“. Electronic Thesis or Diss., Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0001.
Der volle Inhalt der QuelleA deep understanding of plasma transport at the edge of a magnetically confined fusion device is mandatory for a sustainable and controlled handling of the power exhaust. In the next-generation fusion device ITER, technological limits constrain the peak heat flux on the divertor. For a given exhaust power the peak heat flux is determined by the extent of the plasma footprint on the wall. Heat flux profiles at the divertor targets of X-point configurations can be parametrized by using two length scales for the transport of heat in SOL. In this work, we challenge the current interpretation of these two length scales by studying the impact of divertor geometry modifications on the heat exhaust. In particular, a significant broadening of the heat flux profiles at the outer divertor target is diagnosed while increasing the length of the outer divertor leg. Modelling efforts showed that diffusive simulations well reproduce the experimental heat flux profiles for short-legged plasmas. Conversely, the broadening of the heat flux for a long divertor leg is reproduced by a turbulent model, highlighting the importance of turbulent transport not only in the main SOL but also in the divertor. These results question the current interpretation of the heat flux width as a purely main SOL transport length scale. In fact, long divertor leg magnetic configurations highlighted the importance of asymmetric divertor transport. We therefore conclude that main SOL and divertor SOL transport cannot be arbitrarily disentangled and we underline the importance of the divertor magnetic geometry in enhancing asymmetric turbulent transport with the potential benefit of an unexpected power spreading
Cadier, Benoît. „Fibres autorenforcées pour modules d'abonnés : optimisation, caractérisation“. Poitiers, 1998. http://www.theses.fr/1998POIT2289.
Der volle Inhalt der QuelleVadon, Mathieu. „Extraction de bore par oxydation du silicium liquide pour applications photovoltaïques“. Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI067/document.
Der volle Inhalt der QuelleBoron extraction from liquid silicon is a step within a new chain of processes aimed to purify silicon that meets purity requirements specific to photovoltaic applications. This thesis focuses mostly on cold gas processes that involve the injection of a mixture of Ar-H2-H2O gases onto electromagnetically stirred liquid silicon. A second similar method ("plasma processes") that involves the injection of thermal plasma made from an Ar-H2-H2O mixture has also been studied. A model is needed to minimize energy consumption by optimizing the process.We want to be able to predict the flow of silicon from the reactive surface (oxidation speed), the flow of boron from the surface (to have the purification speed) and the passivation threshold. For a given setting, the passivation threshold is the limit oxydant partial pressure at injection beyond which a passivating silica layer appears on the surface of the liquid silicon, which interrupts the purification. In order to minimize the energy consumption, and for that matter , in order to speed up the process, we want to inject oxydant in a quantity just below the passivation threshold.Previous studies have shown that the limiting factor for the oxidation and purification speed is the transport of oxidant in the gas phase. That's why we have made a 1D reactive-diffusive model at thermodynamical equilibrium of the gaseous boundary layer. According to this model the effect of the formation of silica aerosols is to divide by two the flow of oxydant towards the surface, which is useful for the simplification of CFD simulations. This effect of the formation of silica aerosols on oxidant flows can also be found without the hypothesis of thermodynamical equilibrium of silica aerosols with the gas phase, as confirmed by simulations and experiments.Regarding the estimation of the purification speed, we have selected the most realistic values of the enthalpy of formation of HBO(g) and of the activity coefficient of boron in liquid silicon.We could get good estimates of the purification speed at different temperatures and levels of oxidant concentrations at injection, by using the selected thermodynamical values and by supposing that the surface reaction products HBO(g) and SiO(g) diffuse similarly. A reason for this similar diffusion of SiO(g) and HBO(g) might be a common and simultaneous precipitation , due to specific dynamics of nucleation and growth that need to be investigated further. Those results for cold gas processed could also be obtained for a plasma experiment.However for the plasma experiment, silica aerosols can be formed only in a very thin layer near the surface and this result needs confirmation from other experiments.Temperature measurement and control for electromagnetically levitating liquid silicon under a flow of oxidant were achieved. With more time, quantitative results could be achieved to measure thermodynamical data on impurities without contaminations.Regarding the prediction of the passivation threshold, we justified a thermodynamical equilibrium at surface of SiO(g) with Si(l) and SiO2(s/l) at passivation threshold with the spreading of silica particles over the liquid silicon surface with the stirring. We show that the passivation layer is compatible with silica aerosols only if those aerosols are not in equilibrium with the gas phase. Therefore the kinetics of formation of silica aerosols should be studied further. A previous empirical formula on the prediction of the passivation threshold for experiments where H2O is the oxidant has been confirmed using our CFD model. A passivation experiment has shown the absence of impact of silica aerosols on oxidant transport when the oxidant is O2
Fernandez, Vincent. „Etude de l'influence du bore et de l'oxygène sur les propriétés de thermodésorption du carbone après exposition à un plasma de deutérium“. Aix-Marseille 1, 1992. http://www.theses.fr/1992AIX11039.
Der volle Inhalt der QuelleGuillemaut, Christophe. „Modélisation du bord d'un plasma de fusion en vue d'ITER et validation expérimentale sur JET“. Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4081/document.
Der volle Inhalt der QuelleThe conditions required for fusion can be obtained in tokamaks. In most of these machines, the plasma wall-interaction and the exhaust of heating power are handled in a cavity called divertor. However, the high heat flux involved and the limitations of the materials of the plasma facing components (PFC) are problematic. Many researches are done this field in the context of ITER which should demonstrate 500 MW of DT fusion power during ~ 400 s. Such operations could bring the heat flux on the PFC too high to be handled. Its reduction to manageable levels relies on the divertor detachment involving the reduction of the particle and heat fluxes on the PFC. Unfortunately, this phenomenon is still difficult to model. The aim of this PhD is to use the modelling of JET experiments with EDGE2D-EIRENE to make some progress in the understanding of the detachment. The simulations reproduce the observed detachment in C and Be/W environments. The distribution of the radiation is well reproduced by the code for C but with some discrepancies in Be/W. The comparison between different sets of atomic physics processes shows that ion-molecule elastic collisions are responsible for the detachment seen in EDGE2D-EIRENE. This process provides good neutral confinement in the divertor and significant momentum losses at low temperature, when the plasma is recombining. Comparison between EDGE2D-EIRENE and SOLPS4.3 shows similar detachment trends but the importance of the ion-molecule elastic collisions is reduced in SOLPS4.3. Both codes suggest that any process capable of improving the neutral confinement in the divertor should help to improve the modelling of the detachment
Tamain, Patrick. „Etude des flux de matière dans le plasma de bord des tokamaks : alimentation, transport et turbulence“. Aix-Marseille 1, 2007. http://www.theses.fr/2007AIX11060.
Der volle Inhalt der QuelleParticle transport in the edge of tokamaks plays a decisive role both in the center on plasma performances, since it governs the building of density profiles from external particle fuelling, and in the edge on the lifetime of plasma facing components, since it determines particle and energy fluxes reaching the wall. However, this subject has been little explored due to the complexity of modelling the interaction, in the same volume, of the plasma with strong particle, momentum and energy sources and sinks. In the perspective of ITER, the capability of gas puffing systems to reach required density levels without degrading the confinement, as well as the properties of density profiles and flows near the pedestal and in the SOL, remain open questions. This thesis contributes to the effort aiming at giving a better understanding of the mechanisms governing particle fluxes in the edge plasma and their impact on these questions. In a first phase of our work, we present an original approach for the modelling of fuelling by gas puffing, focusing on the thermal impact of the injection on the plasma. On the basis of analytical and numerical models with a reduced number of dimensions, we demonstrate the existence of thermal bifurcations trigerred by the injection and their importance in the dynamics of the neutral penetration and of the plasma relaxation. In the case of Tore Supra, we show that the local cooling linked to a strong injection allows a deeper penetration of particles (r/a = 1. 1 to r/a = 0. 9), but can also lead to a thermal instability of the whole plasma below a given ratio heating power / particle source. The extrapolation of this study for ITER remains pessimistic on the penetration depth of neutrals. However, the sensitivity of the results of these simplified models to the interaction between the parallel and perpendicular directions show that the developpement of numerical tools modelling coherently particle transport in both directions is necessary to progress on these questions. This led to the design of a 3D code presented in the second part of this work. This new tool is a full-torus code, including curvature effects. It solves electrostatic fluid drift equations without scale separation hypothesis, which allows to address with the same tool issues linked to large scale transport as well as micro-turbulence. Two versions of the code have been developped and validated : one treats exclusively closed field lines ; the other, more demanding from the numerical point of view, includes both the Scrape Off Layer (SOL) and the external part of the confined plasma. In a last part, the code is used to address the issue of poloidal asymmetries of parallel flows in the SOL which are observed experimentally but whose origin is not fully clear yet. Simulations reproduce the order of magnitude of measured amplitudes and evidence two different mechanisms which are likely to play a role in this phenomenon, the first at large scales, the other linked to turbulence. The former leans on a coupling between large scale drifts and curvature effects in the SOL while the latter is linked to the ballooning of the radial turbulent flux on the low field side. Finally, the importance of the plasma parallel resistivity on the characteristics of the turbulent transport is analysed as well as the impact of a localized particle injection on the local properties of turbulence
Lediankine, Andrei͏̈. „Mesures spectroscopiques de la densité et de la température électronique au bord du plasma dans TORE SUPRA“. Aix-Marseille 1, 1996. http://www.theses.fr/1996AIX11043.
Der volle Inhalt der QuelleKlungsupya, P. „Nucleotide excision repair of the plasmid borne NFA2 gene in Saccharomyces cerevisiae“. Thesis, Swansea University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637808.
Der volle Inhalt der QuelleSousa, R?mulo Ribeiro Magalh?es de. „Nitreta??o i?nica sem efeito de borda :desenvolvimento e avalia??o de uma nova t?cnica“. Universidade Federal do Rio Grande do Norte, 2006. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12793.
Der volle Inhalt der QuelleCoordena??o de Aperfei?oamento de Pessoal de N?vel Superior
The ionic nitriding process presents some limitations related with the control of the thickness of the layer and its uniformity. Those limitations that happen during the process, are produced due to edge effects, damage caused by arcing arc and hollow cathode, mainly in pieces with complex geometry and under pressures in excess of 1 mbar. A new technique, denominated ASPN (active screen shapes nitriding) it has been used as alternative, for offering many advantages with respect to dc plasma conventional. The developed system presents a configuration in that the samples treated are surrounded by a large metal screen at high voltage cathodic potencials, (varying between 0 and 1200V) and currents up to 1 A. The sample is placed in floting potential or polarized at relatively lower bias voltages by an auxiliary source. As the plasma is not formed directly in the sample surface but in the metal screen, the mentioned effects are eliminated. This mechanism allows investigate ion of the transfer of nitrogen to the substrate. Optical and electronic microscopy are used to exam morphology and structure at the layer. X-ray difration for phase identification and microhardness to evaluate the efficiency of this process with respect to dc conventional nitriding
O processo de nitreta??o i?nica apresenta uma s?rie de limita??es relacionadas com o controle da espessura da camada e de sua uniformidade. Essas limita??es s?o produzidas devido a efeitos de bordas e de c?todo oco que ocorrem durante o processo, principalmente em pe?as com geometria complexa e em press?es do processo superiores a 2 mbar. Assim uma nova t?cnica, denominada ASPN (Active screen plasma nitriding) est? sendo usada como alternativa, por oferecer muitas vantagens em rela??o ao plasma dc convencional. O sistema desenvolvido apresenta uma configura??o em que as amostras a serem tratadas permanecem envolvidas por uma tela que atua como c?todo com tens?o dc variando entre 0 e 1200V e correntes de at? 1 A. A amostra pode permanecer em potencial flutuante ou ser polarizada por uma fonte auxiliar. Como o plasma n?o ? formado diretamente na superf?cie das amostras e sim na tela, os efeitos citados s?o eliminados. Este mecanismo permite investigar a transfer?ncia de nitrog?nio para o substrato por microscopia ?ptica e microscopia eletr?nica de varredura para exames da morfologia e da estrutura, difra??o de raios-X para identifica??o de fases e os ensaios de microdureza permitem avaliar a efici?ncia deste processo em rela??o ? nitreta??o dc convencional
Eliaoui, Morad. „Caractérisation, modèlisation et synthèse de films minces de nitrure de bore (BN) par dépôt chimique en phase vapeur assisté par plasma (PECVD)“. Metz, 2006. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2006/Eliaoui.Mourad.SMZ0605.pdf.
Der volle Inhalt der QuelleBoron nitride (BN) is a compound that exists under two crystallographic structures, the hexagonal form (h-BN), and the cubic form (c-BN). The latter one is a very valuable material for applications in optics and electronics. The first part of this work, was to study the deposition of thin films of boron nitride in a microwave plasma enhanced chemical vapor deposition (PECVD) reactor, and in particular to study how to synthesize the cubic phase. For that purpose, it is necessary to optimize the ionic bombardment, and for that aim, an RF signal was applied to the sample holder, to polarize it by self bias effect. In order to get a control on it, we did perform some characterisations of the plasma properties by Langmuir probe measurements. The second part was to characterize the deposited layers by infra-red transmission spectroscopy. It appears that the films of h-BN are nanocrystallized and texturated, the orientation of the optical axis of the crystallites being dependent on the deposition conditions. In order to simulate the spectra, we have developed an optical model of thin films transmission, and we have used it to determine the optical parameters of h-BN, by fitting the experimental spectra. The optical behavior of films is modelized thanks to the expression of the dielectric function of the medium, which has been expressed, on the one hand, by an expression of the effective dielectric function of the literature, and on the other hand, by an iterative calculation which we have developed
Aguiar, Gyselle Viana. „Individual effect and of the time of the year on the composition of the plasma seminal and teh quality of the coast of the the state of the CearÓ. Universidade Federal do CearÃ, 2008. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=4707.
Der volle Inhalt der QuelleThis study aimed to evaluate rainy and dry season effect on plasma seminal composition and semen quality of 17 crossbred male goats raised in tropical region and to investigate if the biochemical composition of seminal plasma (SP) is correlated to semen quality in relation to the season of the year. Other objective of this experiment was to evaluate if the phospholipase A2 (PLA2) activity level in the SP affects the ejaculate and epididymal spermatozoa. This study was divided into three experiments: in the first phase, seventeen male goats were used and then eight animals with low or high PLA2 activity in SP were separated to the second and third phases. In the first experiment, the ejaculates were collected in artificial vagina, weekly, the SP was separated to evaluate the biochemical parameters and biweekly for quality semen determination. The sperm was diluted in coconut water added 2,5% of egg yolk (200 x 106 sperm/mL) and stored at 4 oC for 48 hours. The vigor (0-5) and motility (1-100%) were measured at 2, 24 and 48 hours after cooling by thermoresistance test (TRT). Slides of sperm were made during TRT and 200 cells were classified as normal or abnormal cellular morphology. The fructose, citric acid, total proteins, calcium, phosphorus, magnesium level and the PLA2 activity level in the SP were measured. In the second experiment, eight bucks were separated in two groups according to PLA2 activity level in SP, in group I (<6.7U/mL) and group II (> 11.0 U/mL). The semen was obtained by artificial vagina, diluted and separate in two samples: the first aliquot was the control treatment (nonwashed semen) and the second aliquot was centrifuged at 550 g for 10 minutes to remove the SP (washed semen). In the third experiment, the semen of the eight bucks was collected and the SP obtained by centrifugation. The SP of each buck was added to aliquots of epididymal spermatozoa pool collected from another male goat and a ninth aliquot was added only to diluent (control). After that, the final dilution (200 x 106 sperm/mL) was made in all samples. In the second and third experiments, after the treatment and final dilution, the semen samples were stored at 4 oC for 48 hours and an aliquot was incubated at 38 oC and evaluated to vigor and motility at 0, 2, 12, 24 and 48 hours of cooling. Slides of sperm were made during TRT and 200 cells were classified as normal or abnormal morphology. In all experiments, the semen quality decreased with time (p<0,001). In the first experiment, the semen obtained in the rainy season was better quality than semen collected in the dry season of the year. In addition, the fructose, citric acid, total proteins, phosphorus and magnesium levels in the SP were higher in rainy season, while the PLA2 activity was lower in this period. The fructose, citric acid and total proteins concentration showed positive correlations to vigor and motility in both seasons. The total sperm morphology alterations (TSMA) showed negative correlation with fructose level and positive correlations with citric acid, total proteins concentrations and PLA2 activity level. In the second experiment, the treatment (washed semen) improved the seminal quality, mainly in washed semen of the group I. The PLA2 activity level showed no effect on sperm performance in the ejaculate spermatozoa, except at 48h in washed semen and at 24h in the non-washed semen. Finally, in the third experiment, the SP addition on epididymal spermatozoa decreased the seminal parameters and this effect was higher in group II. However, the TSMA were lower when the PLA2 activity was higher. These results indicated that male goats raised in tropical region showed better seminal quality in the rainy season. In addition, the fructose, citric acid, total proteins, phosphorus and magnesium concentration levels in the SP were higher in rainy season, while the PLA2 activity was lower in this period. The correlations between the seminal and biochemical parameters in SP could indicate that the differences in the semen parameters in the rainy and dry season occurred due the biochemical parameter variations. The SP addition during the semen storage at 4 oC decreased the seminal quality. However the PLA2 activity level was not a determinant factor of the seminal quality in the ejaculate spermatozoa. Therefore, it cannot be used as an indicative of the spermatic quality of male goats raised in tropical region
Este trabalho teve por objetivo avaliar o efeito da Ãpoca chuvosa e seca do ano sobre a composiÃÃo do plasma seminal (PS) e os parÃmetros seminais de 17 caprinos sem padrÃo racial definido (SPRD), criados em clima tropical, alÃm de avaliar se a composiÃÃo bioquÃmica do PS apresenta correlaÃÃo com os parÃmetros seminais, em funÃÃo da Ãpoca do ano, assim como, investigar se o nÃvel de atividade da fosfolipase A2 (FLA2) no PS de caprinos pode ser utilizado como indicativo da qualidade espermÃtica e se esse nÃvel exerce influÃncia na preservaÃÃo dos espermatozÃides ejaculados e epididimÃrios quando conservados a 4 ÂC, por 48 horas. O estudo foi realizado em trÃs etapas: na primeira foram utilizados dezessete machos caprinos e a partir desta, oito bodes com diferentes nÃveis de atividade de FLA2 no PS foram selecionados para realizaÃÃo da segunda e terceira etapas. No primeiro experimento durante a Ãpoca chuvosa e seca, os ejaculados dos animais foram coletados semanalmente, em vagina artificial, para avaliaÃÃo bioquÃmica do PS e a cada 14 dias para determinaÃÃo dos parÃmetros seminais. O sÃmen foi diluÃdo em Ãgua de coco-2,5% gema (200 x 106 sptz/mL), resfriado a 4 ÂC por 48 horas e avaliado o vigor e a motilidade Ãs 2, 24 e 48 horas de resfriamento (T2, T24 e T48), pelo teste de termorresistÃncia lento (TTR). EsfregaÃos do sÃmen diluÃdo foram confeccionados durante o TTR e 200 cÃlulas foram avaliadas e classificadas morfologicamente em normais ou anormais. Determinaram-se ainda as concentraÃÃes de frutose, Ãcido cÃtrico, proteÃnas totais, Ca, P, MG e nÃvel de atividade da FLA2. No segundo experimento, oito caprinos divididos, em funÃÃo do nÃvel de atividade da FLA2 no PS em: grupo I (<6,70 U/mL) e o grupo II (>11,00 U/mL). O sÃmen foi coletado, diluÃdo e dividido em duas alÃquota : a primeira constituiu o tratamento controle (sÃmen nÃo lavado) e a segunda foi centrifugada para remoÃÃo do PS (sÃmen lavado). No terceiro experimento, o sÃmen dos oito animais foi coletado e centrifugado para recuperaÃÃo do PS e adicionados a alÃquotas de um Ãnico âpoolâ de espermatozÃides epididimÃrios obtidos de caprinos castrados cirurgicamente. Uma nona alÃquota foi adicionada apenas de diluidor (grupo controle). Em seguida, procedeu-se a diluiÃÃo final em todas as amostras utilizando o mesmo diluidor. No segundo e terceiro experimentos, apÃs a realizaÃÃo dos tratamentos e diluiÃÃo final, o sÃmen foi resfriado a 4 ÂC por atà 48 horas e amostra de cada tratamento foi avaliada pelo TTR Ãs 0 (fresco), 2, 12, 24 e 48 horas de resfriamento. EsfregaÃos do sÃmen foram confeccionados para avaliaÃÃo da morfologia espermÃtica. Em todos os experimentos, a qualidade espermÃtica diminuiu à medida que se prolongou o tempo de preservaÃÃo (p < 0,001). No experimento 1, o sÃmen apresentou qualidade superior na Ãpoca chuvosa e tambÃm as concentraÃÃes de frutose, Ãcido cÃtrico, proteÃnas totais, P e Mg foram maiores nesta Ãpoca. A FLA2 apresentou menor atividade na Ãpoca chuvosa (p < 0,05). A concentraÃÃo de frutose, Ãcido cÃtrico e proteÃnas totais mostraram correlaÃÃes positivas com o vigor e a motilidade e negativas com a TDM, nas duas Ãpocas. Em relaÃÃo Ãs alteraÃÃes morfolÃgicas totais (AMT), a concentraÃÃo de frutose mostrou correlaÃÃes negativas, enquanto as de Ãcido cÃtrico, proteÃnas totais e atividade da FLA2, positivas. Os nÃveis de fÃsforo no PS apresentaram correlaÃÃo com os parÃmetros seminais apenas na Ãpoca seca, sendo negativa para vigor, motilidade e AMT e positiva para TDM. A concentraÃÃo de Mg correlacionou-se positivamente com a motilidade na Ãpoca chuvosa e AMT na seca. No segundo experimento, o tratamento influenciou a qualidade seminal principalmente no grupo I, sendo o desempenho espermÃtico superior no sÃmen lavado. O nÃvel de atividade da FLA2 nÃo afetou a qualidade dos espermatozÃides ejaculados, exceto em T48 do sÃmen lavado e T24 do sÃmen nÃo lavado. Enquanto no terceiro experimento, a adiÃÃo do PS aos espermatozÃides epididimÃrios diminuiu a qualidade espermÃtica e este efeito foi mais pronunciado quando o nÃvel de atividade de FLA2 foi maior. Contudo, no que se refere e AMT, a adiÃÃo do PS foi benÃfica, reduzindo o nÃmero de alteraÃÃes. Os resultados do presente estudo indicam que caprinos criados em clima tropical apresentam melhor qualidade espermÃtica no perÃodo chuvoso, alÃm das concentraÃÃes de frutose, acido cÃtrico, proteÃnas totais, P e Mg serem mais elevados nesta Ãpoca, enquanto a atividade da FLA2 foi menor neste perÃodo. As correlaÃÃes entre os parÃmetros seminais e a composiÃÃo bioquÃmica do PS podem indicar que as diferenÃas detectadas quanto à qualidade espermÃtica entre as Ãpocas do ano deve-se justamente Ãs variaÃÃes na concentraÃÃo destes componentes. A presenÃa do PS durante a conservaÃÃo do sÃmen caprino a 4 ÂC reduziu a qualidade espermÃtica, contudo o nÃvel de atividade da FLA2 nÃo foi um fator determinante da qualidade seminal para os espermatozÃides ejaculados, por isso, nÃo deve ser utilizado como indicativo de qualidade espermÃtica de caprinos criados em regiÃo de clima tropical
Boussadi, Amine. „Optimisation d'un procédé de dépôt plasma micro-onde pour l'élaboration de substrats de diamant fortement dopés au bore“. Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCD065/document.
Der volle Inhalt der QuelleThe main objective of this PhD thesis is the optimization of diamond growth conditions in a MPACVD reactor in order to one hand, synthesize single crystal diamond films with low dislocation density, prerequisite to their use in the field of power electronics and on the other hand, synthesize thick intrinsic and boron doped monocrystalline diamond films (>100 microns) on (111)-oriented substrates, crystallographic orientation which is well known to promote twinning. In a first part, a process of inflection and confinement of the dislocations has been developed using (100) pyramidal shape substrates coupled with specific growth conditions. This innovative and original study open the way for the fabrication of single crystal diamond films with low defect density. In a second part, the effect of different growth parameters has been studied to optimize our growth process for (111) orientation. It was thus demonstrated the existence of a narrow window of growth parameters pressure, microwavepower, temperature and methane concentration which ensures a good trade-off between crystalline quality and growth rate, allowing the synthesis of heavily boron-doped diamond thick films on this specific orientation, thus opening the possibility of combining the n-type doping efficiency and achieving vertical bipolar components for applications in hightemperaturehigh-voltage electronics
Kocan, Martin. „Ion tempeture measurements in the scrape-off layer of the Tore Supra Tokamak“. Thesis, Nancy 1, 2009. http://www.theses.fr/2009NAN10116/document.
Der volle Inhalt der QuelleThe thesis describes measurements of the scrape-off layer (SOL) ion temperature Ti – an important but yet rarely measured parameter – with a retarding field analyzer (RFA) probe in the limiter tokamak Tore Supra. The thesis is organized in four chapters. In the first chapter, some well known facts about nuclear fusion, limiter SOL, Langmuir probes, etc. are briefly recalled. Various diagnostics for SOL Ti measurements developed in the past are addressed as well. The second chapter is dedicated to the RFA. The principle of the RFA, technical details and operation of the Tore Supra RFA, and the influence of instrumental effects on RFA measurements are addressed. It is concluded that the influence of instrumental effects on RFA Ti measurements is relatively small. In the third chapter, the systematic measurements of Ti (as well as other parameters) in the Tore Supra SOL are presented. It is shown that Ti / Te >1 (with Te being the electron temperature) in the SOL but also in the confined plasma, and increases with radius. Also important result is that while SOL Ti changes significantly, following the core properties rather closely, SOL Te hardly changes at all. In the final chapter the present status of three ongoing projects aimed at the independent validation of SOL Ti measurements in Tore Supra is presented: the development of the segmented tunnel probe for fast SOL Ti measurements, the measurement of edge ion temperature in Joint European Torus (JET) tokamak, and the comparison of RFA with charge exchange recombination spectroscopy in Tore Supra
Baehr, Olivier. „Elaboration par dépôt chimique en phase vapeur assisté par plasma (PECVD) de films minces de nitrure de bore (BN) sur phosphure d'indium (InP)“. Metz, 1997. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1997/Baehr.Olivier.SMZ9737.pdf.
Der volle Inhalt der QuelleIn the present work, Boron Nitride (BN) thin films, which are known as being electrically insulating, chemically and thermally stable, have been proposed as gate insulator on Indium Phosphide (InP) for the realisation of metal-insulator-semiconductor field affect transistor (misfet). The important requirement for the deposition process on InP, is the use of a low substrate temperature in order to reduce surface damage and therefore to maintain good electrical metal-insulator-semiconductor (mis) characteristics. In this way, we have developed both radio-frequency plasma enhanced chemical vapor deposition (RF-PECVD) and microwave-PECVD. The films were characterized by several techniques, infrared and ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, ellipsometry, X-ray diffraction. The electrical properties of the Au/BN/InP MIS structures have been evaluated by capacitance-voltage, current-voltage measurements and deep level transients spectroscopy (DLTS). The deposited layers were identified as being essentially hexagonal-Bn, with a certain amount of carbon, resulting from the boron precursor. The optical index and the optical band gap have been evaluated in the 1. 50-1. 77 and 3. 7-5. 9 eV ranges respectively, according to the PECVD technique. The BN films deposited by both RF and microwave PECVD techniques, are consistent with the results reported in the literature. These considerations show that the PECVD processes are well adapted for the growth of BN thin films. The elctrical Au/BN/InP MIS characteristics have not been improved significantly, the results being vey similar to those obtained in the literature, with more classical materials (SiO2, Si3N4. . . ) as gate insulator on InP. To date, the eeffective reduction of the interface state density on InP and consequently the industrial InP-MISFET production, seem to be compromised in a general way
Mekkaoui, Mohamed. „Transport des atomes et des molécules dans les plasmas fluctuants de bord des machines de fusion“. Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4784/document.
Der volle Inhalt der QuelleEdge plasma of tokamaks manifests high level of fluctuations amplitude (>50%). It has been demonstrated that such a fluctuations affect significantly the transport of neutral particles, and in particular the slow particles as molecules and sputtered impurities. That is their penetration depth in the plasma is enhanced in the average. Then turbulent fluctuations are now implemented in the monte carlo transport code EIRENE used for the design of ITER
Nascimento, Antonia SÃmia Fernandes do. „ExpressÃo, purificaÃÃo e caracterizaÃÃo estrutural da bdh-2 recombinante, uma espermadesina presente no plasma seminal de bode (Capra hircus)“. Universidade Federal do CearÃ, 2010. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=4513.
Der volle Inhalt der QuelleO cDNA da bodesina Bdh-2 presente no plasma seminal de caprino (Capra hircus) foi subclonado no vetor de expressÃo pTrcHis TOPO utilizado para transformar cÃlulas E.coli Top 10 One Shot. Os clones recombinantes foram selecionados atravÃs de crescimento em meio LB-Broth contendo 50 μg/mL de ampicilina e amplificaÃÃo do gene por PCR. A sÃntese da proteÃna recombinante rBdh-2 fusionada com cauda de histidina foi monitorada atravÃs de SDS-PAGE seguido por immunobloting usando anticorpo monoclonal anti histidina. A produÃÃo da rBdh-2 atravÃs da induÃÃo a baixas temperaturas nÃo se mostrou satisfatÃria. A maior produÃÃo da rBdh-2 ocorreu com IPTG 1,5 mM apÃs 2 horas de induÃÃo. O mÃtodo utilizado para a purificaÃÃo da proteÃna recombinante rBdh-2 foi atravÃs de cromatografia de afinidade em coluna His-Trap seguida por cromatografia de troca-iÃnica em coluna de DEAE-Sephacel. A estrutura secundÃria da rBdh-2 foi avaliada atravÃs do perfil espectral de dicroÃsmo circular (CD) que confirmou a predominÃncia de estruturas secundÃrias do tipo folhas-β, a presenÃa de um baixo conteÃdo de estruturas nÃo-ordenadas e de hÃlices-. A rBdh-2 manteve sua estrutura estÃvel atà 35 ÂC. No entanto, mudanÃas significativas foram observadas a partir de 40 ÂC referentes à descaracterizaÃÃo do espectro de CD.
The Bdh-2 bodhesin cDNA present in seminal plasma of goat was subcloned in the expression plasmid pTrcHis TOPO used to transform E. coli Top10 One shot cells. The recombinant clones were selected by growth in 50 μg/mL ampicillin-containing LB-Broth medium and PCR amplifications. The recombinant protein synthesis was monitored by SDS-PAGE followed by immunoblotting using monoclonal anti-His antibody. The production of the rBdh-2 through low temperature was not satisfactory. A greater production of the rBdh-2 occurred with IPTG 1.5 mM after 2 h of induction. The method utilized to the purification of the rBdh-2 was realized in affinity chromatography on a His-Trap column following ion-exchange chromatography on a DEAE-Sephacel column. The secondary structure of the rBdh-2 was evaluated through spectral profile circular dichroism (CD) and confirmed the prevalence of secondary structures like β-sheets, the presence of a low content of unfolded structures and helices-. The rBdh-2 structure remained stable up to 35 ÂC. However, significant changes were observed from 40 ÂC related to a distortion of the spectrum of CD.
Nascimento, Antonia Sâmia Fernandes do. „Expressão, purificação e caracterização estrutural da bdh-2 recombinante, uma espermadesina presente no plasma seminal de bode (Capra hircus)“. reponame:Repositório Institucional da UFC, 2010. http://www.repositorio.ufc.br/handle/riufc/15683.
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The Bdh-2 bodhesin cDNA present in seminal plasma of goat was subcloned in the expression plasmid pTrcHis TOPO used to transform E. coli Top10 One shot cells. The recombinant clones were selected by growth in 50 μg/mL ampicillin-containing LB-Broth medium and PCR amplifications. The recombinant protein synthesis was monitored by SDS-PAGE followed by immunoblotting using monoclonal anti-His antibody. The production of the rBdh-2 through low temperature was not satisfactory. A greater production of the rBdh-2 occurred with IPTG 1.5 mM after 2 h of induction. The method utilized to the purification of the rBdh-2 was realized in affinity chromatography on a His-Trap column following ion-exchange chromatography on a DEAE-Sephacel column. The secondary structure of the rBdh-2 was evaluated through spectral profile circular dichroism (CD) and confirmed the prevalence of secondary structures like β-sheets, the presence of a low content of unfolded structures and helices-. The rBdh-2 structure remained stable up to 35 °C. However, significant changes were observed from 40 °C related to a distortion of the spectrum of CD.
O cDNA da bodesina Bdh-2 presente no plasma seminal de caprino (Capra hircus) foi subclonado no vetor de expressão pTrcHis TOPO utilizado para transformar células E.coli Top 10 One Shot. Os clones recombinantes foram selecionados através de crescimento em meio LB-Broth contendo 50 μg/mL de ampicilina e amplificação do gene por PCR. A síntese da proteína recombinante rBdh-2 fusionada com cauda de histidina foi monitorada através de SDS-PAGE seguido por immunobloting usando anticorpo monoclonal anti histidina. A produção da rBdh-2 através da indução a baixas temperaturas não se mostrou satisfatória. A maior produção da rBdh-2 ocorreu com IPTG 1,5 mM após 2 horas de indução. O método utilizado para a purificação da proteína recombinante rBdh-2 foi através de cromatografia de afinidade em coluna His-Trap seguida por cromatografia de troca-iônica em coluna de DEAE-Sephacel. A estrutura secundária da rBdh-2 foi avaliada através do perfil espectral de dicroísmo circular (CD) que confirmou a predominância de estruturas secundárias do tipo folhas-β, a presença de um baixo conteúdo de estruturas não-ordenadas e de hélices-. A rBdh-2 manteve sua estrutura estável até 35 °C. No entanto, mudanças significativas foram observadas a partir de 40 °C referentes à descaracterização do espectro de CD.
Auphan, Thomas. „Analyse de modèles pour ITER ; Traitement des conditions aux limites de systèmes modélisant le plasma de bord dans un tokamak“. Phd thesis, Aix-Marseille Université, 2014. http://tel.archives-ouvertes.fr/tel-00977893.
Der volle Inhalt der QuelleGireesh, Guruprasad. „INFLUENCE OF PROCESSING VARIABLES ON MICROSTRUCTURE DEVELOPMENT AND HARDNESS OF BULK SAMPLES OF TWO NOVEL CERAMICS PREPARED BY PLASMA PRESSURE COMPACTION“. University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1144246756.
Der volle Inhalt der QuelleAngleraud, Benoit. „Etude de l'ablation par laser U. V. De cibles de nitrure de bore : application à la réalisation de couches minces“. Limoges, 1995. http://www.theses.fr/1995LIMO0022.
Der volle Inhalt der QuelleEliaoui, Morad Bath Armand Ahaitouf Ali. „Caractérisation, modèlisation et synthèse de films minces de nitrure de bore (BN) par dépôt chimique en phase vapeur assisté par plasma (PECVD)“. [S.l.] : [s.n.], 2006. ftp://ftp.scd.univ-metz.fr/pub/Theses/2006/Eliaoui.Mourad.SMZ0605.pdf.
Der volle Inhalt der QuelleSoltani, Ali. „Croissance de films minces de nitrure de bore hexagonal et cubique par dépôt chimique en phase vapeur assisté par plasma : caractérisations optiques et électriques“. Metz, 2001. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2001/Soltani.Ali.SMZ0134.pdf.
Der volle Inhalt der QuelleThe aim of this work was to synthesise cubic boron nitride thin films (c-BN) by chemical vapour deposition assisted by microwave plasma (2,45 GHZ), in order to carry out a device based on surface acoustic waves (SAW). We initially obtained the hexagonal phase (h-BN), analysed the deposition parameters ad the conditions of the growth which led to a good reproducibility of the layers. The growth c-BN thin films is very delicate and is generally obtained with physical vapour deposition methods (PVD). We succeeded in the fabrication of cubic phase (c-BN) by a chemical vapour deposition (CVD) method and we could elaborate this material successfully by applying an RF bias (13,56 MHz) to the substrates. The BN films were characterized by infrared (IRTF), MicroRaman (MRS), m-lines spectroscopies, as by electrical (I(V), C(V)) and physicochemical (XPS) methods. We developed a method of determination of the orientation of the optical axis "c" of the h-BN films by infrared spectroscopy, while working at oblique incidence. Indeed, with this technique is possible to excite the Lo modes due to the Berreman effect. This allowed us to extract a new "effect" dielectric function which takes into account the preferential orientation of crystallites. Using this method, we show that it is possible to modify the "c" axis orientation by changing the plasma power or the bias of the substrates. The synthesized films correspond to a mixture of h-BN and c-BN phases. The technique developed using IR allows us to show that the "c" axis of the h-BN sublayer is parallel to the substrate surface, allowing thus the growth of c-BN. These results were also corroborated by high resolution transmission electron microscopy measurements (HRTEM). As for PVD techniques, the two important parameters for the synthesis of the c-BN by PECVD are the energies and the magnitude of the incident flux of ions. In addition, electric analyses allowed us to put forward some properties of the BN as its rather large sensitivity to room moisture and its high resistivity, which should make it possible to determinate better precautions of use in the realization of microelectronic devices
Soltani, Ali Bath Armand. „Croissance de films minces de nitrure de bore hexagonal et cubique par dépôt chimique en phase vapeur assisté par plasma Caractérisations optiques et électriques /“. [S.l.] : [s.n.], 2001. ftp://ftp.scd.univ-metz.fr/pub/Theses/2001/Soltani.Ali.SMZ0134.pdf.
Der volle Inhalt der QuelleDuchaine, Julian. „Caractérisation de l'implantation par immersion plasma avec pulsion(r) et intégration dans la fabrication de transistors FD-SOI et Trigate“. Toulouse 3, 2012. http://www.theses.fr/2012TOU30197.
Der volle Inhalt der QuelleThe industry of microelectronics will update regularly its "roadmap" for its international technological developments. The development of new technological processes is accelerating, driven by the need for portable electronics, personal computers with more powerful, telecommunications and multimedia, as well as the very important development of electronics in the automobile world. This race requires the integration of implantation processes with low energy and high dose (based on components). To meet the demand of industrial, IBS has developed its own prototype of plasma immersion ion implanter (PULSION (r)). This type of tool is very attractive to manufacturers because it offers performance and production rates (wafer / hour) with a lower manufacturing cost than conventional implanter (ion beam). This thesis aims to characterize the processes of P-type implantation by plasma immersion using the tool installed at the LETI "PULSION "to integrate in the manufacture of new transistors generations (FD-SOI ultimate Trigate for nano-wires). Many experimental studies have been performed to understand the physical and chemical mechanisms involved during the plasma immersion implantation. Understanding these mechanisms is much more complicated than ion beam implantation because the substrate is constantly immersed in the plasma and all ion species are implanted into the substrate. So, we observed different behavior of the implanted boron atoms between the two implantation techniques. The plasma and implantation conditions were optimized in order to integrate Pulsion (r) processes in the manufacture of FD-SOI and Trigate transistors. The first results show that plasma immersion implantation provides, on planar components (FD-SOI), the same electrical performance as ion beam implanter. Against by performance improved significantly on Trigate transistors. Further developments processes should improve again its performance
Gracias, William Agnelo. „The numerical study of filament dynamics in tokamak scrape-off layer plasmas“. Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0731.
Der volle Inhalt der QuelleFilamentary transport has been experimentally observed in a multitude of magnetically confined fusion devices, especially of the tokamak type. Filaments are carriers of large quantities of particles and heat and as such, their presence in the SOL has implications for the target surface design in future fusion reactors. To better understand their nature, this doctoral thesis studies filaments through computer simulations as isolated structures and spontaneously forming structures, using a 3D fluid model called the TOKAM3X. Parametric studies using the model for studying the effect of the plasma's parallel resistivity and magnetic shear, and also the filament's parallel extension and size/density amplitude are performed and analysed. The studies reveal the strong impact of the parallel resistivity on filament velocities and hence their lifetimes in the SOL. The doctoral work also looked at the impact of strong local magnetic shear and the separatrix on the motion and generation of filaments. The results from the simulations performed reveal that strong shear mechanisms may be key to the destruction and formation of filaments. Further, a comparison of spontaneously forming and seeded filaments shows that seeded filaments do not behave completely the same way as spontaneously forming ones. But their mean velocity characteristics are still retained to a good degree