Orientador: Edison Bittencourt / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-09T15:54:46Z (GMT). No. of bitstreams: 1 Vieira_AdalenaKennedy_D.pdf: 3876527 bytes, checksum: 24d0e24d715ff4f8fefc97ffd5a4e1b9 (MD5) Previous issue date: 2007 / Resumo: Em todo o mundo inicia-se uma nova era. A qualidade de vida e segurança dependem cada vez mais da capacidade de toda humanidade em resolver problemas cada dia mais complexos e demorados. Com o advento da comunicação e a globalização o tempo cada vez mais torna-se um bem escasso e precioso. Os materiais semicondutores usados para desempenhar as funções lógicas e de memória de alta velocidade utilizados no processamento de informação e hardware de armazenagem são os materiais mais difíceis de serem produzidos. Com relação a estes materiais nesta indústria, a capacidade de transformação é enorme, pois o que era o equipamento mais moderno num piscar de olhos passa a ser obsoleto. Assim, avanços nas áreas de tecnologias de informação estão relacionados a avanços em semicondutores e conseqüentemente em materiais. Conforme aumenta a funcionalidade dos chips, aumentam também substancialmente as alternativas para melhorá-los, porque a demanda por este produto não para de crescer e aumenta exponencialmente com relação à população que os consome. Para satisfazer à demanda por densidades mais elevadas nos chips, serão necessárias novas tecnologias de empacotamento e interconexão e a integração destas com toda a tecnologia microeletrônica. É, pois, neste contexto que se insere o presente trabalho. Um dos objetivos principais foi a obtenção de uma cobertura que pode ser um início de uma nova tecnologia para o desenvolvimento de um ¿microchip¿ sobre materiais poliméricos. É o nascer de uma nova era na área de materiais e dispositivos eletro-eletrônicos. Para a indústria nacional e para o Pólo Industrial de Manaus, talvez seja uma tecnologia de ponta com um material mais barato e acessível a todos. Para a execução deste trabalho foram feitos planejamentos experimentais visando melhorar as condições ¿ótimas¿ para o recobrimento por spin coating. Através da deposição de filmes de óxido de silício sobre lentes oftálmicas produziu-se os filmes de óxido de sílicio que foram depositados através de um reator de Microwave Electron Cyclotron Resonance, com o auxílio de um campo magnético em um plasma constituído por uma mistura de argônio, oxigênio e silana. Esse método de deposição é conhecido como ¿ECR¿. A estrutura dos filmes de óxidos de silício depositados foi estudada através de transmitância na região do visível. A morfologia das superfícies recobertas com os filmes foi analisada por Microscopia Óptica e também através de Microscopia de Varredura Eletrônica (MEV). Os resultados de transmitância para os filmes mostram que na medida em que a camada é depositada são formadas estruturas que melhoram a proteção oferecida pela cobertura. As micrografias ópticas revelaram que as lentes sofrem um ¿stress¿ em razão da diferença do coeficiente de expansão entre os dois materiais. As micrografias de MEV mostraram, também, que as superfícies melhores protegidas pelo óxido de silício são as obtidas através de fabricação e moldagem feita com resina acrílica, como comprovam os testes anti-risco. A análise de ângulo de contato do filme mostrou que a cobertura serve como camada aderente ao polímero, mas não como camada hidrofóbica, pois o polímero ainda assim absorve água. As medidas de parâmetros S encontradas foram tiradas com base nas características dos protótipos ensaiados e de acordo com as limitações da resposta em frequência do equipamento utilizado para o ensaio. O resultado dos ensaios também não pode ser melhor detalhado, pois o material foi depositado sem a expectativa dessa finalidade inicialmente. Podemos, entretanto, comprovar que a metodologia é viável e a partir do mesmo principio poderão ser desenvolvidas diversas utilidades para essa técnica inovadora / Abstract: A new era has begun all around the world. The quality of life and health depends more and more on the human capacity of resolving problems that are becoming longer and more complex day by day. As communication and globalization advance, time becomes scarcer and more precious. The semiconductor materials which are used to activate the logical functions, the high velocity memory used in processing information and the storage ¿hardware¿ are the most difficult materials produced in this area. The ability to change is enormous, due to the fact that what was considered the most modern equipment has become obsolete in the blink of an eye. Consequently, the advances in the areas of technological information are related to the advances in those in semiconductors and as result in materials. As the use of the ¿chip¿ increases, the alternatives also become varied, with the objective of improving the chip¿s functions, this is because the demand for the product is getting stronger, increasing, when referring to the population, the search for these products. This study has achieved a covering which can be perceived as a beginning to New Technology, in order to create a ¿microchip¿ with polymeric materials. It¿s the start of a new era when dealing with the area of electro-electronic materials and models. For the National Industry and for Manaus¿ Industry Pole, it might be viewed as cheaper and more accessible technology for all. An adaptation of a reactor has become full filled that produces electronic components for a deposition on a polymer substratum (ophtalmic lenses) for the attainment of a treatment of alternative anti-reflexive. This methodology is used in the industry of electronic components, more known as "chip". In this work they had been experiment design facts to optimize the excellent conditions for the covering for spin coating. Through the deposition of silicon oxide films on ophtalmic lenses one produced the silicon oxide films that had been deposited through a reactor of Microwave Electron Cyclotron Resonance, with aid of a magnetic field, a plasma constituted by a mixture of argon, oxygen and silane.This method of deposition is known as "ECR". The structure of deposited the silicon oxide films was studied through transmittance in the region of the visible light. The morphology of the surfaces re-covered with the films was analyzed by Optic Microscopy and also through Scanning Electron Microscopy Analysis (MEV). The results of transmittance for the films show that the measure where the layer is deposited form structures that improve the protection offered for the covering. The MEV micrographs had shown, also, that the surfaces best protection for silicon oxide are the gotten ones through acrylic resin, as they prove the anti-risk tests. The analysis of angle of contact of the film showed that the covering does not serve as hydrophobic layer. The measurements of parameter S which were found, were based on characteristics of the resulted prototypes and the answer limitations regarding the frequency of the equipment used for these readings. Moreover, the overall results can¿t be better detailed due to the fact that the material wasn¿t deposited with this objective. The methodology is viable, and based on the same principles it can develop diverse utilities to this innovate technique / Doutorado / Ciencia e Tecnologia de Materiais / Doutor em Engenharia Química

Orientador: Caio Glauco Sánchez / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-23T14:06:22Z (GMT). No. of bitstreams: 1 Neves_RenatoCruz_M.pdf: 25784234 bytes, checksum: ce1b9833db6f80c61b19cd8781d17a52 (MD5) Previous issue date: 2013 / Resumo: O desafio da tecnologia de reforma de gás de gaseificação é realizar a conversão de alcatrão e particulados em um gás, pois estes contaminantes podem trazer diversos problemas ao sistema de gaseificação como entupimento de filtros e corrosão. Dentre os equipamentos e métodos para a reforma do gás de gaseificação, encontra-se o plasma. Neste trabalho foi projetado, construído e ensaiado um sistema de reforma de gás de gaseificação proveniente de um reator de gaseificação utilizando a tocha de plasma. O sistema de reforma a plasma é constituído pela tocha de plasma inserida na garganta de um tubo convergente-divergente instalado na tubulação de saída do reator de gaseificação. A fonte de alimentação da tocha de plasma é o modelo Powermax1250 e a tocha é o modelo T80M, ambos da marca Hypertherm. A tocha de plasma utiliza nitrogênio como gás de trabalho, opera com pressão de 4; 0 bar no modo arco elétrico com corrente contínua, plasma térmico, não-transferido e alcança temperaturas superiores a 1673 K em distâncias menores que 30 mm. Na gaseificação foi utilizada a serragem de Peroba e Garapeira, fator de ar de 0; 22, velocidade de fluidização de 0,57 m.s-1 e utilizou-se 550 mm de altura do leito fixo de areia quartzosa. A coleta de alcatrão e particulado foi adaptada da norma CEN/BT/TF 143 ("Biomass gasification - Tar and particules in product gases - sampling and analysis"). Nas condições estudadas e analisadas deste trabalho, o valor obtido para a vazão mássica de alcatrão e material particulado foi de (5; 26+0; 58)10-3 g.s-1 para a gaseificação convencional enquanto que para a gaseificação utilizando a tecnologia da reforma de plasma foi de (3; 97+0; 14)10-3 g.s-1, que representou uma redução de 24; 52 % / Abstract: The technologic challenge on reformation of gasification gas is to convert tar and particulate matter into gas, because they can cause various problems on gasification system as corrosion and filters clogging. Among the equipment and methods for gasification gas reformation, it is used the plasma. In this work was designed, built and tested a system for gasification gas reformation from a gasification reactor using a plasma torch. The plasma system is formed by plasma torch inserted in the throat of a convergent-divergent tube installed in the outlet pipe of the gasification reactor. The power supply of the plasma torch is Powermax1250 and the model T80M plasma torch, both from Hypertherm brand. The plasma torch uses nitrogen as working gas, operates at a pressure of 4; 0 bar with arc current mode, thermal plasma, non-transferred and reaches temperatures above 1673 K in distances of less than 30 mm. In the gasification was used Peroba and Garapeira sawdust, air factor 0:22, fluidization velocity 0,57 m.s-1and 550 mm height fixed bed of quartz sand. The tar and particulate collection was adapted from CEN/BT/TF 143 (Biomass gasification - tar and particules in product gases - sampling and analysis). Under the conditions studied and analyzed in this work, the value obtained for the mass flow of tar and particulate material was (5; 26+0; 58)10-3 g.s-1 for conventional gasification while for using the reformation of gasification gas was de (3; 97+0; 14)10-3 g.s-1, which represented a reduction of 24:52 % / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica

Orientadores: Munemasa Machida, José Helder Facundo Severo / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-23T20:24:15Z (GMT). No. of bitstreams: 1 Nascimento_Fellypedo_D.pdf: 5773174 bytes, checksum: 260b32bb9f860cd7cda3a4c349ce7817 (MD5) Previous issue date: 2013 / Resumo: Este trabalho tinha como objetivo desenvolver um diagnostico para medir temperaturas e densidades de elétrons (Te e ne) em plasmas de tokamaks, utilizando espectroscopia no visível de emissões de impurezas presentes no plasma. Foram obtidos resultados para medidas locais de temperaturas e densidades de elétrons no plasma dos tokamaks NOVA-UNICAMP e TCABR, a partir de medidas de emissões espectrais de íons de carbono e oxigênio. Para este propósito foi utilizada a relação entre o fluxo de partículas de impurezas e as emissões espectrais provenientes delas. Esta relação foi combinada com um método interativo para obter valores de Te e ne. Tais resultados foram alcançados baseados na teoria de que o fluxo de partículas de um determinado elemento presente no plasma não depende do comprimento de onda em que seus íons estão emitindo radiação, no regime de equilibrio colisional-radiativo. No tokamak NOVA-UNICAMP foram obtidos resultados utilizando emissões espectrais de carbono e oxigênio, porem apenas em um nível de ionização de tais elementos (C1+ e O1+). Nesta maquina, as medidas de três linhas de emissão provenientes de cada íon foram efetuadas de forma simultânea, ou seja, em um único disparo. Já no tokamak TCABR foram gerados resultados com emissões de três níveis de ionização do carbono (C1+, C2+ e C5+), mas as aquisições de dados nesta maquina foram realizadas em descargas diferentes, tendo sido medido um comprimento de onda emitido por um dado íon em cada disparo. Para todos os íons utilizados, e nas duas maquinas em que foram feitas medidas, os valores obtidos para as temperaturas de elétrons estão de acordo com os esperados para as regiões do plasma onde e maior a probabilidade de que cada íon em questão emita radiação. No caso especifico do TCABR, onde foram feitas medidas de emissões de três níveis de ionização do carbono, isto fica mais evidente, pois valores mais elevados de temperatura foram observados para maiores níveis de ionização. As densidades de elétrons que foram obtidas concordam em ordem de grandeza com os valores esperados, para todos os íons utilizados no trabalho, nos dois tokamaks. Porem os valores medidos estão acima do esperado, exceto para os resultados obtidos no TCABR com emissões de C5+. No tokamak TCABR foi possível comparar os resultados de ne obtidos pelo nosso método com os que são medidos por interferometria de micro-ondas. Na comparação, notou-se que o perfil temporal de ne medido com o nosso método esta em bom acordo com que foi obtido com o interferômetro. De um modo geral, os resultados obtidos foram bons, e podemos considerar que os objetivos deste trabalho de tese foram cumpridos / Abstract: In this work we got results for measurements of local electron temperatures and densities (Te and ne) at NOVA-UNICAMP and TCABR tokamak plasmas, by using visible spectroscopy of line emissions from carbon and oxygen ions, which are impurities in the plasma. For this purpose, we used the relationship between the particle flux and the photon flux emitted by an element (or an ion) at a fixed wavelength. That relationship was combined with an interactive method in order to determine Te e ne values. Such results were achieved based on the theory that the particle flux of a given ion specie in the plasma does not depend on the wavelength of the light emitted by the ion. For NOVA-UNICAMP tokamak we got results using spectral emissions of carbon and oxygen for only one ionization stage of these elements (C1+ and O1+). In this machine, we have made simultaneous measurements of each set of three spectral emissions from each ion specie in the same tokamak shot. For TCABR tokamak we got results using spectral emissions from three ionization stages of carbon (C1+, C2+ and C5+). But the data acquisition in this machine were made in different tokamak discharges, where we measured one spectral emission per time for each ion. The electron temperatures obtained with all ion emissions used in this work and in both machines are in good agreement with the expected values at the plasma position where each kind of ion has larger probability of be radiating. This fact become more evident in the TCABR tokamak, where we have emissions measurements of three carbon ionization stages, because higher Te values were measured for ions at higher ionization stages. All results obtained for electron densities agree in magnitude order, for both machines, with the expected values for this parameter. But the measured values are higher than the expected, except for the results obtained using C5+ emissions at TCABR tokamak. In TCABR was possible to compare the ne results obtained in our method with measurements made using a microwave interferometer. In that comparison we noted that the temporal profile of both diagnostics are in good agreement. The general conclusion is that the results obtained with our method were good and we consider that the objectives of this work were fulfilled / Doutorado / Física / Doutor em Ciências

When an electrically conducting fluid moves through a magnetic field, fluid mechanics and electromagnetism are coupled.<p>This interaction is the object of magnetohydrodynamics, a discipline which covers a wide range of applications, from electromagnetic processing to plasma- and astro-physics.<p><p>In this dissertation, the attention is restricted to turbulent liquid metal flows, typically encountered in steel and aluminium industries. Velocity measurements in such flows are extremely challenging because liquid metals are opaque, hot and often corrosive. Therefore, non-intrusive measurement devices are essential. One of them is the Lorentz force flowmeter. Its working principle is based on the generation of a force acting on a charge, which moves in a magnetic field. Recent studies have demonstrated that this technique can measure efficiently the mean velocity of a liquid metal. In the existing devices, however, the measurement depends on the electrical conductivity of the fluid. <p><p>In this work, a novel version of this technique is developed in order to obtain measurements that are independent of the electrical conductivity. This is particularly appealing for metallurgical applications, where the conductivity often fluctuates in time and space. The study is entirely numerical and uses a flexible computational method, suitable for industrial flows. In this framework, the cost of numerical simulations increases drastically with the level of turbulence and the geometry complexity. Therefore, the simulations are commonly unresolved. Large eddy simulations are then very promising, since they introduce a subgrid model to mimic the dynamics of the unresolved turbulent eddies. <p><p>The first part of this dissertation focuses on the quality and reliability of unresolved numerical simulations. The attention is drawn on the ambiguity that may arise when interpretating the results. Owing to coarse resolutions, numerical errors affect the performances of the discrete model, which in turn looses its physical meaning. In this work, a novel implementation of the turbulent strain rate appearing in the models is proposed. As opposed to its usual discretisation, the present strain rate is in accordance with the discrete equations of motion. Two types of flow are considered: decaying turbulence located far from boundaries, and turbulent flows between two parallel and infinite walls. Particular attention is given to the balance of resolved kinetic energy, in order to assess the role of the model.<p><p>The second part of this dissertation deals with a novel version of Lorentz force flowmeters, consisting in one or two coils placed around a circular pipe. The forces acting on each coil are recorded in time as the liquid metal flows through the pipe. It is highlighted that the auto- or cross-correlation of these forces can be used to determine the flowrate. The reliability of the flowmeter is first investigated with a synthetic velocity profile associated to a single vortex ring, which is convected at a constant speed. This configuration is similar to the movement of a solid rod and enables a simple analysis of the flowmeter. Then, the flowmeter is applied to a realistic three-dimensional turbulent flow. In both cases, the influence of the geometrical parameters of the coils is systematically assessed. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

In this thesis we mainly focus on the study of the turbulent transport of impurity particles in the plasma due to the electrostatic drift wave microinstabilities. In a fusion reactor, the helium produced as a result of the fusion process is an internal source of impurity. Moreover, impurities are released from the material surfaces surrounding the plasma by a variety of processes: by radiation from plasma, or as a result of sputtering, arcing and evaporation. Impurities in tokamak plasmas introduce a variety of problems. The most immediate effect is the radiated power loss (radiative cooling). Another effect is that the impurity ions produce many electrons and in view of the operating limits on density and pressure, this has the effect of replacing fuel ions. For example, at a given electron density, $n_{e}$, each fully ionized carbon ion (used in the wall materials in the form of graphite) replaces six fuel ions, so that a 7\\% concentration of fully ionized carbon in the plasma core, would reduce the fusion power to one half of the value in a pure plasma. Therefore, for all tokamaks it become an immediate and continuing task to reduce impurities to acceptably low concentrations. However, the presence of impurities, with control, can be beneficial for the plasma performance and reduction of strong plasma heat loads on the plasma facing walls. The radiative cooling effect which was mentioned above can be used at the edge of the plasma in order to distribute the plasma heat more evenly on the whole surface of the vessel walls and therefore, reduce significantly plasma heat bursts on the small regions on the divertor or limiter tiles. The experiments at TEXTOR show that the presence of the impurities at the plasma edge can also improve the performance and reduce the turbulent transport across the magnetic field lines. The observed behavior was explained trough the proposed mechanism of suppression of the most important plasma drift wave microinstability in this region, namely, the Ion Temperature Gradient mode (ITG mode) by the impurities. The impurity's positive impact on the plasma performance offered a possibility to better harness the fusion power, however, it is vital for a fusion reactor to have feedback controls in order to keep impurities at the plasma edge and limit their accumulation in the plasma core where the fusion reactions are happening. In order to have control over the impurity transport we first need to understand different mechanisms responsible for its transport. <p><p>One of the least understood areas of the impurity transport and indeed any plasma particle or heat transport in general, is the turbulent transport. Extensive efforts of the fusion plasma community are focused on the subject of turbulent transport. Motivated by the fact that impurity transport is an important issue for the whole community and it is an area which needs fundamental research, we focused our attention on the development of turbulent transport models for impurities and their examination against experiments. In a collaboration effort together with colleagues (theoreticians as well as experimentalist) from different research institutes, we tried to find, through our models, physical mechanisms responsible for experimental observations. Although our main focus in this thesis has been on the impurity transport, we also tried a fresh challenge, and started looking at the problem of drift wave turbulent transport in a different framework all together. Experimental observation of the edge turbulence in the fusion devices show that in the Scrape of Layer (SOL: the layer between last closed magnetic surface and machine walls) plasma is characterized with non-Gaussian statistics and non-Maxwellian Probability Distribution Function (PDF). It has been recognized that the nature of cross-field transport trough the SOL is dominated by turbulence with a significant ballistic or non-local component and it is not simply a diffusive process. There are studies of the SOL turbulent transport using the 2-D fluid descriptions or based on probabilistic models using the Levy statistics (fractional derivatives in space). However, these models are base on the fluid assumptions which is in contradiction with the non-Maxwellian plasmas observed. Therefore, we tried to make a more fundamental study by looking at the effect of the non-Maxwellian plasma on the turbulent transport using a gyro-kinetic formalism. We considered the application of fractional kinetics to plasma physics. This approach, classical indeed, is new in its application. Our aim was to study the effects of a non-Gaussian statistics on the characteristic of the drift waves in fusion plasmas.<p><p>Ce travail de thèse porte sur le transport turbulent d'impuretés dans les plasmas de fusion<p>par confinement magnétique. C'est une question de la plus haute importance pour le développement<p>de la fusion comme source d'énergie. En effet, une accumulation d'impuretés au coeur<p>du plasma impliquerait des pertes d'énergie par radiation, conduisant par refroidissement à<p>l'extinction des réactions de fusion. Il est par contre prévu d'injecter des impuretés dans le<p>bord du plasma, afin d'extraire la chaleur par rayonnement sans endommager les éléments de<p>la première paroi. Ces contraintes contradictoires nécessitent un contrôle précis du transport<p>d'impuretés, afin de minimiser la concentration d'impuretés au coeur du plasma tout en la<p>maximisant au bord. Une très bonne connaissance de la physique sous-jacente au transport<p>est donc indispensable. L'effet de la turbulence, principal mécanisme de transport, sur les impuretés<p>est alors une question centrale. Dans cette thèse, un code numérique, AFC-FL, a été développé sur la base d'une approche ``fluide' linéaire pour la turbulence d'ondes de dérive. Il calcule les taux de croissance qui caractérisent la rapidité de l'amorçage des instabilités. L'analyse de stabilité est complétée par l'évaluation des taux de croissance en présence d'un gradient de densité, un cisaillement magnétique ou un nombre arbitraire de différentes espèces d'impureté. Les formules complètes du flux turbulent d'impuretés pour ces taux de croissance calculés des instabilités des ondes de dérive ont été dérivées. Un modèle de transport anormal qui nous permet d'étudier la dépendence du transport en fonction de la charge d'impureté a été développé. Ce modèle prend en compte les effets collisionnels entre les ions, l'impureté et les particules principales de plasma. Une telle dépendence du transport anormal en fonction de la charge de l'impureté est observée dans les expériences et il a été montré que les résultats obtenus sont en bon accord avec les observations expérimentales. Nous avons également étudié l'effet des impuretés sur le confinement de l'énergie dans les plasmas du tokamak JET. La modélisation de transport a été exécutée pour des plasmas avec injection de néon dans la périphérie du tokamak. Cette technique est utilisée afin d'extraire la chaleur par rayonnement sans endommager la paroi et pour réduire certaines instabilités (ELM). Des simulations du code RITM ont été comparées à des mesures effectuées lors d'expériences au JET. Il a été montré que l'injection de néon mène toujours à une dégradation du confinement par rapport aux décharges sans néon. Cependant, l'augmentation de la charge effective, en raison du presence du néon peut diminuer le taux de croissance d'autres instabilité (ITG) et amèliorer le confinement du coeur du plasma. Ce confinement amélioré du coeur peut alors compenser la dégradation au bord et le confinement global du plasma peut s'améliorer. <p> / Doctorat en sciences, Spécialisation physique / info:eu-repo/semantics/nonPublished

Thermonuclear fusion has potential to offer an economically, environmentally and socially acceptable supply of energy. A promising reactor design to execute thermonuclear fusion is the toroidal magnetic confinement device, tokamak. The tokamak still faces challenges in the major areas which can be categorised into confinement, heating and fusion technology. This thesis addresses the problem of confinement, in particular the role of transport along magnetic field lines perturbed by diverse MHD instabilities.<p><p>Unstable modes such as ideal ballooning-peeling, tearing etc. break closed magnetic surfaces and destroy the axisymmetry of the magnetic configuration in a tokamak, providing deviation of magnetic field lines from unperturbed magnetic surfaces. Radial gradients of plasma parameters have nonzero projections along such lines and drive parallel particle and heat flows which contribute to the radial transport. Such transport can significantly affect confinement as this takes place by the development of neoclassical tearing modes (NTMs) in the core and edge localised modes (ELMs) at the plasma periphery.<p><p>In this thesis, transport of heat through non-overlapped magnetic island chains is first investigated using the 'Optimal path' approach, which is based on the principal of minimum entropy production. This model shows how the effective heat conduction through islands increases with parallel heat conduction and with the perturbation level. A more standard analytical approach for the limit cases of "small" and "large" islands is also presented. Transport of heat through internally heated magnetic islands is next investigated by further development of the 'Optimal path' method. In addition the approach by R. Fitzpatrick, has been extended for this investigation. By application of these approaches to experimental observations made at TEXTOR tokamak, heat flux limit, limiting parallel heat conduction in low collisional plasmas, is elucidated.<p><p>Models to study transport of heat and particles due to ELMs have also been developed. Energy losses during ELMs have been estimated considering contribution from parallel conduction due to electrons and parallel convection of ions, with constant level of the magnetic field perturbation, steady profiles for density and temperature, and by accounting for the heat flux limit. The estimate shows good agreement with experimental observations. The model is developed further by accounting for the time evolution of the perturbation level due to ballooning mode, and of density and temperature profiles. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

No description available.

Active feedback control in magnetic confinement fusion devices is desirable to mitigate plasma instabilities and enable robust operation. Among various diagnostics, optical high-speed cameras provide a powerful, non-invasive diagnostic and can be suitable for these applications. This thesis reports the first application of high-speed imaging videography and deep learning as real-time diagnostics of rotating MHD modes in a tokamak device. The developed system uses a convolutional neural network (CNN) to predict the amplitudes of the ?=1 sine and cosine mode components using solely optical measurements acquired from one or more cameras. Using the newly assembled high-speed camera diagnostics on the High Beta Tokamak – Extended Pulse (HBT-EP) device, an experimental dataset consisting of camera frame images and magnetic-based mode measurements was assembled and used to develop the mode-tracking CNN model. The optimized models outperformed other tested conventional algorithms given identical image inputs. A prototype controller based on a field-programmable gate array (FPGA) hardware was developed to perform real-time mode tracking using the high-speed camera diagnostic with the mode-tracking CNN model. In this system, a trained model was directly implemented in the firmware of an FPGA device onboard the frame grabber hardware of the camera’s data readout system. Adjusting the model size and its implementation-related parameters allowed achieving an optimal trade-off between a model’s prediction accuracy, its FPGA resource utilization and inference speed. Through fine-tuning these parameters, the final implementation satisfied all of the design constraints, achieving a total trigger-to-output latency of 17.6 ?s and a throughput of up to 120 kfps. These results are on-par with the existing GPU-based control system using magnetic sensor diagnostic, indicating that the camera-based controller will be capable to perform active feedback control of MHD modes on HBT-EP.

CNPq, CAPES, FINEP / Devido à alta resistência a corrosão, os aços inoxidáveis possuem uma larga aplicabilidade em diversos setores industriais, seja indústria química, petroquímica ou alimentícia. Buscando atender solicitações ainda mais severas, métodos que melhorem a relação resistência à corrosão e propriedades mecânicas destes aços tem sido objeto de estudo de diversos pesquisadores. Com o objetivo de aumentar a resistência mecânica, dureza superficial e resistência à corrosão dos aços inoxidáveis propôs-se a introdução de nitrogênio em solução sólida pelo processo de SHTPN (Solution Heat Treatment after Plasma Nitriding), em desenvolvimento no GrMaTS/UTFPR. O nitrogênio apresenta algumas vantagens como a redução da tendência à precipitação, e a estabilização da camada passiva. Além disso, o nitrogênio reage na área anódica, o que neutraliza o efeito da acidez melhorando assim a resistência a corrosão. Neste trabalho avaliou-se a resistência à corrosão do aço inoxidável ferrítico AISI 409, após a obtenção de uma camada martensítica enriquecida com nitrogênio em solução solida por meio do processo SHTPN. Em seguida foram avaliados os efeitos da temperatura de revenimento (200, 400 e 600 °C) e da temperatura de austenitização (950 e 1050 °C) na microestrutura, dureza e resistência à corrosão da camada martensítica obtida. A resistência à corrosão foi avaliada pela técnica de polarização cíclica em solução de NaCl 0,5 mol/L e os perfis de dureza obtidos por medição de dureza Vickers com carga de 0,05 Kgf (0,49 N). A microestrutura foi avaliada por Microscopia Óptica, Eletrônica de Varredura e por Difração de Raios-X. Os resultados indicam que o tratamento de SHTPN promoveu a formação de uma camada martensítica de nitrogênio, com consequente acréscimo de dureza de 160 HV para 580 HV. O tratamento têmpera após SHTPN não afetou significativamente a dureza do aço, contudo, refinou e melhorou a distribuição da martensita de nitrogênio. Os resultados de corrosão para as condições tratadas e revenidas a 200 °C indicam resistência à corrosão superior ou equivalente à da ferrita do material não tratado (AISI 409). Já as amostras revenidas nas temperaturas de 400 e 600 °C apresentaram um decréscimo na resistência à corrosão, bem como foi observada uma diminuição da dureza da amostra revenida a 600 °C. / Due to high corrosion resistance, stainless steels have a wide applicability in many industrial sectors, such as, chemical, petrochemical and food industries. With the demand for corrosion resistance materials becoming more stringent, methods that improve the relation corrosion resistance and mechanical properties of these steels has been studied by many researchers. In order to increase the mechanical strength, surface hardness and corrosion resistance of stainless steels we proposed the introduction of nitrogen in solid solution by the process of SHTPN (Solution Heat Treatment after Plasma Nitriding), under development in GrMaTS/UTFPR . Nitrogen in solid solution has some advantages over materials that have only carbon in the structure such lower tendency for precipitation and stabilization of the passive layer. In addition, the nitrogen reacts in the anodic area, which neutralizes the effect in the acidity thus improving the corrosion resistance. This research evaluate the corrosion resistance of ferritic stainless steel AISI 409, after obtaining a martensitic layer enriched with nitrogen, in solid solution, by SHTPN process. Effects of tempering temperature (200, 400 and 600 °C) and austenitization temperature (950 to 1050 °C) in the microstructure, hardness and corrosion resistance of martensitic layer obtained. Corrosion resistance was evaluated by cyclic polarization technique, with a NaCl solution 0.5 mol/L, and hardness profiles obtained by measuring the Vickers hardness with a load of 0.05 kgf (0.49 N). Samples microstructure was investigated by optical microscopy, scanning electron microscopy and X- ray diffraction. Results indicate that the treatment of SHTPN promoted the formation of a martensitic nitrogen layer, with consequent increase of hardness of 160 HV to 580 HV on sample surface. Tempering treatments, realized after SHTPN did not significantly affect the hardness of steel, however, has refined and improved the distribution of nitrogen martensite. Corrosion results of sample treated and annealed at 200 °C indicate higher or equal resistance to that of the untreated ferrite materials (AISI 409) corrosion. Samples that were annealed at temperatures of 400 and 600 °C showed a decrease in the corrosion resistance as well as a decrease in hardness was observed in the sample tempered at 600 °C.

CNPq, CAPES, FINEP / Devido à alta resistência a corrosão, os aços inoxidáveis possuem uma larga aplicabilidade em diversos setores industriais, seja indústria química, petroquímica ou alimentícia. Buscando atender solicitações ainda mais severas, métodos que melhorem a relação resistência à corrosão e propriedades mecânicas destes aços tem sido objeto de estudo de diversos pesquisadores. Com o objetivo de aumentar a resistência mecânica, dureza superficial e resistência à corrosão dos aços inoxidáveis propôs-se a introdução de nitrogênio em solução sólida pelo processo de SHTPN (Solution Heat Treatment after Plasma Nitriding), em desenvolvimento no GrMaTS/UTFPR. O nitrogênio apresenta algumas vantagens como a redução da tendência à precipitação, e a estabilização da camada passiva. Além disso, o nitrogênio reage na área anódica, o que neutraliza o efeito da acidez melhorando assim a resistência a corrosão. Neste trabalho avaliou-se a resistência à corrosão do aço inoxidável ferrítico AISI 409, após a obtenção de uma camada martensítica enriquecida com nitrogênio em solução solida por meio do processo SHTPN. Em seguida foram avaliados os efeitos da temperatura de revenimento (200, 400 e 600 °C) e da temperatura de austenitização (950 e 1050 °C) na microestrutura, dureza e resistência à corrosão da camada martensítica obtida. A resistência à corrosão foi avaliada pela técnica de polarização cíclica em solução de NaCl 0,5 mol/L e os perfis de dureza obtidos por medição de dureza Vickers com carga de 0,05 Kgf (0,49 N). A microestrutura foi avaliada por Microscopia Óptica, Eletrônica de Varredura e por Difração de Raios-X. Os resultados indicam que o tratamento de SHTPN promoveu a formação de uma camada martensítica de nitrogênio, com consequente acréscimo de dureza de 160 HV para 580 HV. O tratamento têmpera após SHTPN não afetou significativamente a dureza do aço, contudo, refinou e melhorou a distribuição da martensita de nitrogênio. Os resultados de corrosão para as condições tratadas e revenidas a 200 °C indicam resistência à corrosão superior ou equivalente à da ferrita do material não tratado (AISI 409). Já as amostras revenidas nas temperaturas de 400 e 600 °C apresentaram um decréscimo na resistência à corrosão, bem como foi observada uma diminuição da dureza da amostra revenida a 600 °C. / Due to high corrosion resistance, stainless steels have a wide applicability in many industrial sectors, such as, chemical, petrochemical and food industries. With the demand for corrosion resistance materials becoming more stringent, methods that improve the relation corrosion resistance and mechanical properties of these steels has been studied by many researchers. In order to increase the mechanical strength, surface hardness and corrosion resistance of stainless steels we proposed the introduction of nitrogen in solid solution by the process of SHTPN (Solution Heat Treatment after Plasma Nitriding), under development in GrMaTS/UTFPR . Nitrogen in solid solution has some advantages over materials that have only carbon in the structure such lower tendency for precipitation and stabilization of the passive layer. In addition, the nitrogen reacts in the anodic area, which neutralizes the effect in the acidity thus improving the corrosion resistance. This research evaluate the corrosion resistance of ferritic stainless steel AISI 409, after obtaining a martensitic layer enriched with nitrogen, in solid solution, by SHTPN process. Effects of tempering temperature (200, 400 and 600 °C) and austenitization temperature (950 to 1050 °C) in the microstructure, hardness and corrosion resistance of martensitic layer obtained. Corrosion resistance was evaluated by cyclic polarization technique, with a NaCl solution 0.5 mol/L, and hardness profiles obtained by measuring the Vickers hardness with a load of 0.05 kgf (0.49 N). Samples microstructure was investigated by optical microscopy, scanning electron microscopy and X- ray diffraction. Results indicate that the treatment of SHTPN promoted the formation of a martensitic nitrogen layer, with consequent increase of hardness of 160 HV to 580 HV on sample surface. Tempering treatments, realized after SHTPN did not significantly affect the hardness of steel, however, has refined and improved the distribution of nitrogen martensite. Corrosion results of sample treated and annealed at 200 °C indicate higher or equal resistance to that of the untreated ferrite materials (AISI 409) corrosion. Samples that were annealed at temperatures of 400 and 600 °C showed a decrease in the corrosion resistance as well as a decrease in hardness was observed in the sample tempered at 600 °C.