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Law, Daniel A. "Dusty plasmas and plasma crystals." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298743.
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Mercieca, Kayron. "Plasma spectroscopy in pinch plasmas." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/7118.
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Magnetic fields play a very important role in the dynamics of plasmas. Through interactions with the ions and electrons within plasmas, their behaviour and evolution can be drastically influenced. It is the Zeeman effect that is responsible for the splitting of radiative lines observed. Zeeman spectroscopy is a tool used for the diagnosis of these magnetic fields within plasmas when the extent of this line splitting is observable. Aluminium is chosen as an element to model as it is easy to place within a pinch plasma. It is also relatively easy to ionise Aluminium into being Hydrogen-like within the conditions of pinch plasmas. The calculation of Lyman Alpha and Lyman Beta spectral lineshapes for a Hydrogen-like Aluminium plasma is presented from a fundamental standpoint. The Stark and Zeeman effects are explored and modelled. Modelling of the former is aided by an adapted version of the APEX code by R. Lee in order to calculate the probability distribution of electric fields around a radiator ion in the plasma. Both effects are calculated together as a quantum perturbation to the π = 1, 2, 3 atomic energy levels including fine structure. The lineshapes resulting from this calculation are compared with H-Line’s models (a code also by R. Lee) and shown to be significantly more detailed, including visible Zeeman splitting for test external magnetic fields of B = 100 T and B = 1000 T. Natural and Doppler broadening are also modelled. These extra broadening effects (in particular Doppler) are shown to be destructive to discernable lineshape detail, largely preventing magnetic field diagnosis through Zeeman spectroscopy. Lastly, Lyman Alpha and Lyman Beta are modelled for plasmas with Z-pinch and X-pinch conditions in order to determine the viability of visible Zeeman line splitting.
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Ridenti, Marco Antonio 1986. "Diagnóstico e modelagem de plasmas gerados por micro-ondas e aplicações." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276981.
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Orientadores: Jayr de Amorim Filho, Marco Aurélio Pinheiro de LimaTese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: Neste trabalho plasmas não térmicos gerados em pressão atmosférica e sustentados por ondas de superfície em micro-ondas, tendo o argônio como gás de alimentação, foram estudados experimentalmente e teoricamente tendo em vista aspectos pouco compreendidos de suas propriedades físicas e aplicações voltadas ao tratamento de biomassa. Medições da composição elementar e dos parâmetros físicos foram realizados por meio de técnicas de diagnóstico baseadas em espectrometria de massa e espectroscopia óptica de emissão. O sistema físico foi modelado por meio das equações de continuidade das espécies neutras e carregadas, da equação do calor e da equação de Boltzmann dos elétrons, que foram acopladas utilizando um procedimento auto-consistente. Uma vez obtido o quadro geral das propriedades do plasma, foi estabelecida a condição de operação adequada ao tratamento das amostras derivadas de biomassa. O tratamento foi realizado sobre quatro tipo de amostras: lignina, xilana, celulose e bagaço de cana-de-açúcar. Dentre as contribuições importantes deste trabalho podem ser destacadas: (i) a verificação experimental do papel dos íons moleculares do argônio no processo de contração da descarga; (ii) a determinação do perfil axial no plasma dos principais íon positivos e negativos, da densidade e temperatura eletrônicas, da temperatura do gás e da densidade do estado metaestável Ar(1s5); (iii) verificação da seletividade do tratamento a plasma, tendo sido observada uma alteração significativa dos espectros de absorção no infravermelho nos casos da lignina e da xilana, mas não no caso da celulose. Esse último resultado sugere uma rota inusitada para novas tecnologias de deslignificação e síntese de novos materiais a partir de biomassa
Abstract: In this work non-thermal argon plasmas produced at atmospheric pressure and sustained by microwave surface waves were theoretically and experimentally studied in view of their non understood aspects and also the applications aimed at biomass treatment. Measurements of elemental composition and physical parameters were carried by means of plasma diagnostic techniques such as mass spectrometry and optical emission spectroscopy. Plasma modelling based on the self-consistent solution of the continuity equations of the neutral and charged species, the heat equation and the electron Boltzmann equation was developed to describe the plasma properties. Once a complete picture of the plasma behaviour was obtained, a promising condition for plasma treatment was established. Four types of biomass derived material were plasma treated: lignin, cellulose, xylan and sugarcane bagasse. Among the important contributions of this work one may highlight the following: (i) the experimental verification of the crucial role of argon molecular ions in the discharge contraction; (ii) axial profile determination of the main positive and negative ions, the electronic temperature and density, the gas temperature and the metastable state Ar(1s5) density; (iii) important modification of the infrared absorption spectra after plasma treatment in the cases of lignin and xylan, but not in the case of cellulose, suggesting a unexpected route for delignification and new materials synthesis from biomass
Doutorado
Física
Doutor em Ciências
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Iwamae, Atsushi. "Plasma polarization spectroscopy on magnetically confined plasmas." 京都大学 (Kyoto University), 2005. http://hdl.handle.net/2433/144851.
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Kyoto University (京都大学)0048
新制・論文博士
博士(工学)
乙第11656号
論工博第3848号
新制||工||1351(附属図書館)
23469
UT51-2005-D574
京都大学大学院工学研究科機械物理工学専攻
(主査)教授 藤本 孝, 教授 斧 髙一, 教授 木田 重雄
学位規則第4条第2項該当
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Litwinczik, Vítor. "Irradiação sonora de placas planas com descontinuidades /." Florianópolis, SC, 1998. http://repositorio.ufsc.br/xmlui/handle/123456789/77388.
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Dissertação (Mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico.Made available in DSpace on 2012-10-17T03:39:53Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T23:04:45Z : No. of bitstreams: 1 140044.pdf: 28854372 bytes, checksum: 5a1cc766103148dda01e48fdc863c824 (MD5)
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Colina, Delacqua Ligia Maria. "Modélisation/diagnostic de production de poussières dans un plasma H₂au contact d’une cible C/W : Contribution à l’étude des interactions plasma/surface dans les machines de fusion thermonucléaire." Paris 13, 2012. http://scbd-sto.univ-paris13.fr/intranet/edgalilee_th_2012_colina_delacqua.pdf.
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Ce travail de thèse a porté sur la caractérisation expérimentale d’un plasma d’hydrogène au contact de cibles de carbone ou tungstène généré dans le réacteur microonde multi dipolaire CASIMIR II. Ce dernier, développé pendant ce projet de thèse, a pour objectif de simuler quelques des processus plasma/surface ayant lieu sous le dome du divertor et dans les régions à l’ombre du plasma (SOL) dans les tokamaks. CASIMIR II se compose de 16 sources dipolaires microondes disposées de manière circulaire le long du périmètre de l’enceinte à vide de manière à obtenir un plasma basse pression (10⁻³ à 10⁻² mbar), haute densité (10⁹ - 10¹¹ cm⁻³) homogène dans tout le volume du réacteur. Des cibles C/W ont été exposées à de tels plasmas. La mise en oeuvre de plusieurs diagnostics in situ spectroscopie optique d’émission, spectrométrie de masse et sonde de langmuir) ont permis d’identifier la nature de quelques produits d’érosion et de constater leur incidence sur les paramètres plasma (Vp' Tₑ‚ nₑ et nᵢ). Un premier modèle 1D collisionnel radial du plasma d’hydrogène généré par une source dipolaire microonde a été développé dans le but de valider et d’aider à l’interprétation des résultats expérimentauxThe work presented in the frame of this thesis dealt with the experimental characterization of a hydrogen plasma in contact with carbon or tungsten target generated in the microwave multidipolar plasma reactor CASIMIR II. This reactor, developed during this thesis project, is envisioned to simulate some plasma / surface processes occuring under the divertor dome and in the far Scrape-off Layer (SOL) regions of tokamaks. The CASIMIR II device is composed of 16 dipolar plasma sources close enough together to ensure large enough homogenous plasma density (10⁹ - 10¹¹ cm⁻³) at low presure (10⁻³ à 10⁻² mbar). Carbon/tungsten targets have been exposed to such plasma. The implementation of several in situ diagnostics (optical emission spectroscopy, mass spectrometry and Langmuir probe) provided us the possibility to identify the nature of some erosion products and observe their effect on plasma parameters (Vp' Tₑ‚ nₑ et nᵢ). A ID collisional radial model of the hydrogen plasma generated by a single microwave dipolar source was developed to validate and help understanding of the experimental results
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Gulko, Ilya Dmitrievich. "Ns Pulse / RF Hybrid Plasmas for Plasma Chemistry and Plasma Assisted Catalysis Applications." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1598271986860656.
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Lavagna, Luis Guillermo Moscoso. "Aerodinâmica da placa plana em movimento não-permanente." Instituto Tecnológico de Aeronáutica, 1992. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=1797.
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Considere-se uma placa plana, imersa num fluido que escoa, a qual executa um movimento não-permanente qualquer. O objetivo básico deste trabalho é calculas numericamente o campo de escoamento em torno da placa e, dessa forma, obter-se os coeficientes aerodinâmicos de sustentação e momento de arfagem. As principais hipóteses simplificadoras são: fluido não-viscoso, escoamento incompressível e irrotacional. O modelo que daí resulta permite a simulação da placa mediante uma distribuição de dipolos normais de intensidade uniforme. Para se obter o campo de velocidades lança-se mão do método dos painéis, sendo que o calculo dos coeficientes aerodinâmicos é feito utilizando-se a equação de Bernoulli linearizada. Os casos considerados para o movimento da placa são: mudança brusca do ângulo de incidência em relação a um escoamento uniforme (problema de Wagner), entrada paulatina numa rajada de canto vivo (problema de Kussner), entrada paulatina numa rajada de intensidade harmonicamente variável (problema de Sears) e movimento harmônico combinado de translação e rotação (problema de Theodorsen). O procedimento de calculo proposto é validado, para cada caso, via comparação com resultados analíticos encontrados na literatura.
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Aguera, João Júlio Mendes 1985. "Estudos dos espectros atômicos e moleculares de plasmas DBD atmosféricos." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278561.
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Orientador: Munemasa MachidaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: Os plasmas DBD, Descargas com Barreira de Dielétrico, em pressões atmosféricas têm despertado grande interesse nas pesquisas nos últimos anos, principalmente pelas suas aplicações práticas: deposição de materiais, tratamento de superfícies, tratamento de cáries, esterilização de bactérias e destruição de células cancerígenas. Estes plasmas são chamados de plasmas não-térmicos e diferem dos plasmas de alta temperatura (estelares e de reatores de fusão nuclear) e dos plasmas térmicos (tochas de plasmas e plasmas industriais), por possuírem temperaturas translacional, eletrônica, vibracional e rotacional distintas. Para determinar a temperatura de plasmas DBD em descargas elétricas nos gases Ar e He, utilizamos um método indireto que avalia a temperatura por meio de um plasma de Nitrogênio molecular formado pela colisão dos plasmas de Ar e He com o Nitrogênio presente no ar. O espectro luminoso deste plasma é medido, as principais linhas de emissão catalogadas e depois analisado com um software específico para determinação de temperaturas de gases moleculares. Também são mostradas aqui algumas das principais técnicas de espectroscopia usadas na captação de espectros luminosos de plasmas laboratoriais, realizadas em dois dispositivos, plasma DBD produzido com jato de seringa, e plasma fracamente ionizado produzido com uma descarga DC entre dois eletrodos
Abstract: Research on DBD (Dieletrical Barrier Discharges) plasmas at atmospheric pressure have attracted attention and great interest on its research upon the last few years, mostly because of its practical applications: material deposition, surface treatment, cavity treatment, bacterial sterilization and cancer cell destruction. These plasmas are called nonthermal plasmas and differ from the high temperature plasmas (stellar and fusion reactors) and thermal plasmas (plasma torches and industrial plasmas) because of its distinct translational, electronic, vibrational and rotational temperatures. For temperature determination in DBD plasmas formed by electrical discharges on Ar and He gases, an indirect method is used evaluating the temperature of molecular nitrogen plasma formed by collision between the Ar and He plasmas with the nitrogen present in air. The luminous specter of this plasma is measured, the principal emission lines cataloged and then analyzed with specific software for molecular gases temperature determination. The main spectroscopic techniques used for analysis of the luminous spectra obtained from two devices: DBD plasma generated by a syringe jet and weakly ionized plasma produced by a DC discharge between two electrodes, are show on this thesis
Mestrado
Física
Mestre em Física
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Wattieaux, Gaëtan. "Détection et métrologie de nanoparticules en suspension dans un plasma froid basse pression." Thesis, Orléans, 2010. http://www.theses.fr/2010ORLE2080.
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Face au développement actuel des nanotechnologies il apparaît important de pouvoir contrôler la taille des nano-objets mis en oeuvre par les industriels aussi bien pour la qualité des produits manufacturés que pour la sécurité des personnes et la protection de l'environnement. Le travail qui a été accompli au cours de cette thèse concernait la recherche de solutions innovantes pour mesurer la taille de nanoparticules en voie sèche. Pour cela nous nous sommes plus particulièrement concentrés sur la physique des plasmas poudreux. En effet l'utilisation d'un plasma permet de favoriser la désagglomération de l'échantillon de poudre que l'on souhaite caractériser et la présence de poussières dans un plasma modifie sensiblement les caractéristiques électriques de ce dernier. Nous avons montré dans un premier temps qu'il est possible de déterminer la taille moyenne de poussières piégées dans une décharge capacitive RF à basse pression à partir de la mesure de la variation des paramètres électriques de cette dernière quand de la poudre s'y forme ou y est injectée. Nous avons également développé une nouvelle technique de granulométrie par sédimentation à basse pression et assistée par plasma. Cette technique consiste à disperser l'échantillon de poudre en l'injectant dans un plasma puis à en déduire sa taille à partir de la mesure de sa vitesse de sédimentation après l'extinction du plasma. Ainsi, il est possible de déterminer la fonction de distribution en taille de l'échantillon de poudre que l'on analyse. Le système que nous avons conçu a été utilisé avec succès pour contrôler en temps réel une ligne de production de nanopoudres au CEA SaclayThe recent development of nanotechnology has made nanoparticle sizing more and more important for the quality of manufactured products as well as for human health and environmental protection. The aim of this thesis was to look for innovative solutions to measure the size and the concentration of nanoparticles in dry environnement. To meet this requirement we focused on the physics of dusty plasmas because the desagglomeration of a powder sample is enhanced when it is exposed to a plasma and the dusts modify signifcantly the electrical properties of the plasma where they are trapped. The first result of this work is the determination of the mean size of dusts that are injected or formed in a RF low pressure capacitive discharge from the variations of the electrical parameters of the plasma and of the discharge. A new particle sizing technique has also been developed. It consists of determining the powder size distribution from the measurement of its sedimentation speed following the extinction of the discharge. The system that has been designed was successfully used to monitor in real time a nanopowder production line based at the CEA Saclay
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Brown, George Scott. "Exploring plasma sheath solutions for planar and cylindrical anodes." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/43771.
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Anode sheaths impact the operation of many practical plasma devices. This complex region is explored in detail for collisional, isothermal (identical specie temperatures), low-temperature plasmas, where sheath dimensions are in the micron range. The selected approach involves postulation of a specific electric field distribution with two shape factors. Previous research regarding planar anodes is verified and expanded upon using greater parameter ranges. 'Z', a dimensionless quantity specifying plasma composition and condition, groups diverse plasmas into 'families' exhibiting similar sheath characteristics. Eta, a nondimensional ratio of electrical energy to thermal energy in the sheath, allows temperature effects to be studied. The investigation focuses on three disparate plasma families that span a range of 1.1729 to 2,1493, at eta values defined by plasma temperatures of 6000 K, 3000 K, and 3000 K. Results indicate that at lower temperatures, charge production in the outer sheath is generic to the electric field distribution, and that the sheaths themselves are nearly unaffected by substantial changes in temperature (i.e., eta). Conversely, sheath density and extent are shown to vary significantly for differing z values. Newly-derived equations governing cylindrical anodes generate sheaths that are virtually identical to corresponding planar cases. It is shown that only those anodes whose radii are comparable to the plasma's characteristic radius (gamma) must be treated with the cylindrical formulation; non-vacuous plasma would require micron-width anodes to be thus affected. Finally, an analytical approach yields solutions that confirm the numerical results, and offers an algebraic approximation for high-eta plasmas.
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Martinelli, Valdisley Jose. "Escoamento natural entre placas planas verticais com aquecimento assimetrico." [s.n.], 1998. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263392.
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Orientador: Kamal Abdel Radi IsmailDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: O objetivo deste trabalho é estudar o desenvolvimento de transferência de calor laminar por convecção natural em canais de placas planas verticais sujeito a aquecimento assimétrico. São analisadas condições de contorno com fluxo de calor uniforme nas paredes das placas e temperatura da parede uniforme. Soluções para escoamento em regime permanente são obtidos para o ar para diferentes fluxos de calor e diferentes temperaturas nas paredes (acima da temperatura do fluido na entrada do canal); bem como para diferentes geometrias do canal (variação da distância entre as placas (b)). As equações foram escritas em diferenças finitas utilizando variáveis primitivas e resolvidas implicitamente, usando discretização central em todos os termos das equações governantes, exceto para o caso de fluxo de calor que foi utilizado diferença unilateral de três níveis nos termos da derivada da temperatma. Os resultados indicam que existe uma distância ótima entre as placas onde ocorre a máxima troca de calor entre as placas e o fluido. Os resultados foram comparados com a literatura, tanto trabalhos numéricos como experimentais
Abstract: This work studies the developm.entof laminar free convection in vertical flat parallel plates with asymmetric heating. Thermal boundary conditions of uniform wall heat fluxes and uniform wall temperature are considered. Solutions of the flow on steady state are obtained for air at different wall heat fluxes and wall temperature differences (above the temperature of the fluid at the channel) and also different geometries of the channel (distance between the plates (b)). The equations were written in finite difference using primitive variables and they were solved by implicitesqueme all the terms of the governing equations, and by means of a three point derivative formula the terms wall temperature at heat fluxes. The results show there is one optimal distance between the plates to maximize the heat transfer. The results were compared with the literature, both numerical and experimentalworks
Mestrado
Termica e Fluidos
Mestre em Engenharia Mecânica
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Ng, Lun Chiu. "Spatial and temporal probing of particle density in UV laser generated plasma and high pressure TE discharge plasma." HKBU Institutional Repository, 1994. http://repository.hkbu.edu.hk/etd_ra/11.
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Lui, Siu Lung. "Spectrochemical analysis of solid samples using resonance-enhanced laser-induced plasma spectroscopy." HKBU Institutional Repository, 2005. http://repository.hkbu.edu.hk/etd_ra/620.
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Lerche, Ernesto Augusto. "Aquecimento do plasma por ondas de Alfvén no tokamak TCABR." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-17072012-141903/.
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Os resultados de uma extensa campanha experimental, realizada no tokamak TCABR, para se investigar a física das ondas de Alfvén e suas aplicações para o aquecimento de plasmas em tokamaks são apresentados. Ao longo das investigações, foram testados dois tipos de antena, tendo sido observado aquecimento considerável do plasma com ambas, mesmo com valor moderado da potência RF injetada no plasma. Diversas configurações de excitação e diversas condições do plasma foram investigadas, e foi verificado que a escolha correta da helicidade da onda excitada PE crucial para se reduzir o acoplamento parasítico com o plasma periférico. Também foi verificada a importância de uma limpeza periódica da superfície das antenas, realizada durante as descargas de limpeza do tokamak, para melhorar o desempenho dos experimentos com aquecimento por ondas de Alfvén. Com a antena original, que produz um espectro poloidal bastante selecionado, a tensão de polarização dinâmica induzida nas antenas observada durante os experimentos era alta, aumentando a taxa de sputtering em seus elementos e podendo, inclusive, levar à disruptura do plasma em potêncis RF mais elevadas. Com o novo tipo de antena, projetado com dimensões poloidais reduzidas, a tensão de polarização induzida caiu pela metade. No entanto, o acoplamento parasítico com a borda do plasma aumentou, como foi indicado por maiores perturbações observadas nos potenciais do SOL, nesse caso. Ademais, a taxa de injeção/ionização de impurezas parece ser maior do que a observada com a antena original em condições semelhantes, como foi indicado pór um aumento maior no sinal do bolômetro durante o pulso RF e por medidas de espectroscopia. Esses fatos sugerem que o espectro excitado pela antena nova é menos seletivo quanto à componente poloidal M, e os modos eletrostáticos devem estar sendo excitados com amplitude considerável. As modificações causadas pela absorção das ondas de Alfvén no perfil radial da temperatura eletrônica do plasma puderam ser estudadas com um radiômetro heteródino de varredura ECE. Esses estudos nos permitiram determinar experimentalmente os perfis radiais de deposição de potência RF no plasma, que estão em surpreendente concordância com os perfis de deposição de potência RF no plasma, que estão surpreendente concordância com os perfis de deposição teóricos, calculados com um código cinético-toroidal para as condições típicas do TCABR. Esses resultados são inéditos em pesquisas com ondas de Alfvén, e reforçam a sua utilização para aquecimento localizado de plasmas e controle de fluxos cizalhados em tokamaks.The results of na extensive experimental campaign performed in the TCABR tokamak to investigate the Physics of the Alfvén wave and its application to tokamak plasma heating are presented. In the course of the experiments, Téo types of Alfvén Wave antennae were studied, and considerable plasma heating was observed in both cases, even with rather small amount of RF Power injected in the plasma. Many antennae configurations and plasma conditions were tried out, and it was verified that the correct choice of the helicity of the excited wave is crucial to reduce the parasitic coupling with the edge plasma. It was also noticed that periodic conditioning of the antenna surface, performed together with the daily tokamak cleaning discharges, also contributes to improve the performance of the heating experiments. With the first antenna type, which produced a rather well defined poloidal spectrum, the dynamic polarication voltage induced in the antennae during the RF experiments was high, causing increased sputtering of its elements and, for higher RF powr input, even plasma disruptions. With the new antenna type, designed with smaller poloidal dimensions, the dynamic polarization voltage of the antenna was reduced twice. However the parasitic coupling with the plasma hás increased, as indicated by stronger perturbations of the electrostatic potentials in the scrape-off layer observed in this case. In addition, the impurity injection/ionization rate also seems to have increased with respect to the previous antenna type in approximately the same conditions, as indicated by a stronger rise in the bolometer signal observed during the RF pulse, and by spectroscopic measurements. These facts suggest that, with the new antenna type, the excited wave spectrum is rather broad with respect to the poloidal wave number M, and electrostatic modes must be excited with quite high amplitude. The change in the radial profiles of the electron temperature due to the Alfvén wave absorption could be studied with a heterodyne sweping ECE radiometer. These sutidies allowed us to determine experimentally the RF Power deposition profiles inside the plasma, which were in surprisingly good agreement with the theoretical deposition profiles, calculated with a kinetic-toroidal code for the TCABR plasma conditions. These results are unprecedented in experimental Alfvén wave research, and strengthen the use of these waves for localized plasma heating and shear flow control in tokamaks.
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Morel, Pierre. "Le modèle "water bag" appliqué aux équation cinétiques des plasmas de Tokamak." Phd thesis, Université Henri Poincaré - Nancy I, 2008. http://tel.archives-ouvertes.fr/tel-00453088.
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Ce travail a porté sur l'étude des instabilités de gradient de température ioniques (ITG) en géométrie cylindrique, le champ magnétique étant supposé constant et dirigé selon l'axe du cylindre. Une fonction de distribution discrète en forme de marche d'escalier est utilisée pour décrire la direction de vitesse parallèle au champ magnétique. L'équation de Vlasov se résume à un système de type multi fluides couplés par l'équation de quasi neutralité. Chaque fluide est décrit par un système fermé d'équations (continuité, Euler et fermeture adiabatique), caractéristiques d'un fluide incompressible, d'ou la dénomination de sac d'eau ou “water bag”. Le recours à cette description water bag est particulièrement intéressant dans le cas de problèmes à une seule dimension en vitesse. Ainsi, dans le cas des plasmas fortement magnétisés, un modèle water bag peut se combiner avantageusement aux modèles dits girocinétiques. Les paramètres associés a la représentation water bag ont pu être identifiés et reliés aux grandeurs macroscopiques par le biais d'une méthode originale d'équivalence au sens des moments. L'analyse water bag des ITG a permis de valider le modèle et les méthodes choisies. Ce travail a également permis de montrer que le concept de water bag peut sans problème prendre en compte des effets variés comme ceux liés a l'introduction d'un rayon de Larmor fini, tout comme à la description d'un plasma composé de plusieurs espèces d'ions.
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Jacobson, Craig Michael. "Electron transport in plasmas with lithium-coated plasma-facing components." Thesis, Princeton University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3615076.
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The Lithium Tokamak Experiment (LTX) is a spherical tokamak designed to study the lowrecycling regime through the use of lithium-coated shells conformal to the last closed flux surface (LCFS). A lowered recycling rate is expected to flatten core Te profiles, raise edge Te, strongly affect n e profiles, and enhance confinement.
To study these unique plasmas, a Thomson scattering diagnostic uses a ≤ 20 J, 30 ns FWHM pulsed ruby laser to measure Te and ne at 11 radial points on the horizontal midplane, spaced from the magnetic axis to the outer edge at a single temporal point for each discharge. Scattered light is imaged through a spectrometer onto an intensified CCD. The diagnostic is absolutely calibrated using a precision light source and Raman scattering. Measurements of n e are compared with line integrated density measurements from a microwave interferometer. Adequate signal to noise is obtained with ne ≥ 2 ×10 18 m–3.
Thomson profiles of plasmas following evaporation of lithium onto room-temperature plasmafacing components (PFCs) are used in conjunction with magnetic equilibria as input for TRANSP modeling runs. Neoclassical calculations are used to determine Ti profiles, which have levels that agree with passive charge exchange recombination spectroscopy (CHERS) measurements. TRANSP results for confinement times and stored energies agree with diamagnetic loop measurements. Results of χe result in values as low as 7 m2/s near the core, which rise to around 100 m2/s near the edge. These are the first measurements of χe in LTX, or its predecessor, the Current Drive Experiment-Upgrade (CDX-U), with lithium PFCs.
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Bazani, Marcio Antonio. "Resfriamento de placas planas por um jato confinado de ar." [s.n.], 2001. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263015.
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Orientador: Carlos Alberto C. AltemaniTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Este trabalho considerou o resfriamento convectivo de placas planas localizadas na superfície de incidência de um jato confinado de ar. Inicialmente o problema foi simulado numericamente, considerando a superfície de incidência do jato aquecida e isotérmica, utilizando dois modelos de turbulência de alto Reynolds distintos: k-e RNG (grupos de renormalização). As simulações foram efetuadas para um escoamento bidimensional incompressível de ar. O método dos volumes de controle foi usado para resolver iterativamente as equações de conservação de massa, quantidade de movimento e energia, bem como as equações de energia cinética turbulenta e taxa de dissipação de energia cinética turbulenta. Os resultados obtidos da simulação de escoamento e da transferência de calor foram comparados com resultados numéricos e experimentais obtidos na literatura numa faixa do número de Reynolds na seção de entrada (8000 < Rej < 20000) e da razão de aspecto (1,0 < H/w < 8,0) do jato. Em seguida, uma montagem experimental foi construída, com três placas planas aquecidas montadas na superfície do jato. Os resultados de testes experimentais de laboratório foram comparados com resultados correspondentes de simulação numérica. Sob condições distintas de aquecimento das três placas, o coeficiente adiabático de transferência de calor, descrito por Moffat (1998), foi utilizado e comparado com resultados do coeficiente convectivo baseado na temperatura de entrada do jato. Nos testes experimentais, o número de Reynolds do jato variou na faixa (9000 < Re < 16000) e a razão de aspecto foi mantida fixa (H/w = 6,0). Foi verificado, pelos resultados experimentais e de simulação, que o coeficiente adiabático (had) depende apenas das condições do escoamento, enquanto que o coeficiente baseado na temperatura de entrada do ar (hin) depende tanto do escoamento quanto da potência dissipada nas placas a montante. Os resultados deste estudo tem aplicações no resfriamento de componentes eletrônicos
Abstract: The convective cooling of discrete heated plates flush mounted on the incidence surface of a confined slot jet was investigated in this Thesis. Initially numerical simulations were performed considering a heated isothermal impingement plate, using two high-Reynolds turbulence models: k-e and RNG (Groups of Renormalization). A control volumes method was used to solve a two-dimensional incompressible airflow. The conservation equations (mass, momentum and energy), and those associated to the turbulence mo del (the turbulent kinetic energy equation and that of its dissipation rate) were solved iteratively by the contral volumes method. The numerical simulation results for the flow and heat transfer were compared with numerical and experimental data obtained from the literature to explore the effects of the jet Reynods number (8000 < Re < 20000), and the aspect ratio (1 < H/w < 8). An experimental apparatus was built, with three heated plates flush mounted on the impingement plate. The obtained experimental results were compared with corresponding numerical simulations. Under distinct heating conditions of the three plates, the adiabatic heat transfer coefficient, described by Moffat (1998), was compared with the convective coefficient based on the inlet air temperature. The experimental tests were performed for a range of 9000 < Rej < 16000 and for a single aspect ratio, Hlw = 6. It was verified, by the experimental results and the numerical simulations, that the adiabatic heat transfer coefficient (had) depends on the flow conditions, while that based on the inlet air temperature (hin) depends both on the flow conditions and power dissipated in the upstream plates. The results of this investigation are relevant to applications in electronics cooling
Doutorado
Termica e Fluidos
Doutor em Engenharia Mecânica
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Gracio, Bilro Castela Maria Luis. "Direct Numerical Simulations of plasma-assisted ignition in quiescent and turbulent flow conditions." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC042/document.
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La combustion assistée par plasma a reçu une attention croissante dans les deux communautés de plasma et de combustion. Les décharges Nanoseconde Répétitive Pulsée (NRP) sont des techniques prometteuse et efficaces pour initier et contrôler les processus de la combustion en particulier quand les systèmes d’allumage conventionnels sont inefficaces ou trop coûteux en énergie. Néanmoins, les phénomènes rencontrés dans la combustion assistée par plasma sont encore mal connus. Les études numériques présentées dans la littérature sont limitées à des simulations 1-D et 2-D dans des conditions au repos. La complexité du problème augmente dans les configurations pratiques où le phénomène d’allumage est contrôlé par le mouvement du fluide ainsi que le mélange autour de la zone de décharge. La simulation numérique directe (DNS) est un outil de recherche puissant pour la compréhension des interactions plasma/combustion/écoulement. Toutefois, le coût de calcul de la combustion turbulente avec un nombre de Reynolds élevé et la cinétique chimique détaillée couplée avec le plasma hors-équilibre est prohibitif. Cette thèse présente un nouveau modèle de couplageplasma-combustion pour introduire les effets des décharges de plasma hors-équilibre dans le système d’équations qui décrit le phénomène de la combustion. Le modèle est construit en analysant les chemins par lesquels l’énergie électrique est transférée au gaz. Ce modèle de décharges NRP permet des simulations multidimensionalesDNS de la combustion et l’allumage assistés par plasma. Les phénomènes physiques complexes de l’allumage assisté par décharges multiples de plasma dans des mélanges au repos et en régime d’écoulement turbulent sont analysés dans cette thèsePlasma-assisted combustion has received increasing attention in both plasma and combustion communities. Nanosecond Repetitively Pulsed (NRP) discharges are a promising and efficient technique to initiate and control combustion processes particularly when conventional ignition systems are rather ineffective or too energy costly. Even though a promising technique, the phenomena occurring in NRP discharges-assisted combustion are still poorly understood. The numerical studies presented in the literature are limited to 1-D and 2-D simulations in quiescent conditions. The problem complexity increases in practical configurations as ignition phenomena are also controlled by the flow and mixing field characteristics in and around the discharge channel. Direct Numerical Simulations (DNS) is a powerful research tool to understand these plasma/combustion/flow interactions. However, the computational cost of fully coupled detailed non-equilibrium plasma and combustion chemistry, and high Reynolds number simulations is prohibitive. This thesis presents a model to describe the effects of non-equilibrium plasma discharges in the set of equations governing the combustion phenomena. Based on the results reported in the literature, the model is constructed by analyzing the channels through which the electric energy is deposited. The two main channels by which the electrons produced during the discharge impact the reactive mixture are considered: 1) the excitation and the subsequent relaxation of the electronic states of nitrogen molecules, which leads to an ultrafast increase of the gas temperature and dissociation of species; and 2) the excitation and relaxation of vibrational states of nitrogen molecules which causes a much slower gas heating. This high level model of NRP discharges allows DNS studies of plasma-assisted combustion / ignition in high turbulent Reynolds number. The complex physics underlying plasma-assisted ignition by multiple discharges in both quiescent and turbulent flow conditions are discussed in the present thesis
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Dubois, Jérôme. "Nouvelle technologie utilisant les plasmas H2 et He pour contrôler la gravure de couches ultraminces à l’échelle nanométrique." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAT079/document.
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Pour la réalisation des transistors FDSOI 22 nm et 3D FinFET 10 nm, la gravure de couches ultraminces de quelques nanomètres d’épaisseur doit être réalisée sans endommagement de la couche sous-jacente et n’est plus envisageable avec les procédés reposant sur les plasmas continus à haute densité. Une nouvelle technologie de gravure est étudiée dans cette thèse : elle consiste à modifier la surface d’un matériau sous l’action d’un plasma et à retirer par voie chimique le matériau modifié sélectivement par rapport au matériau non modifié. Nous nous focalisons ici sur la compréhension de la modification du matériau SiN induite par les plasmas de H2 et He, suivie d’une gravure chimique réalisée en solution de HF. Tout d’abord, un dépôt de conditionnement est développé pour prévenir la contamination du substrat et la dégradation des parois. Des diagnostics en plasmas de H2 et He sont ensuite réalisés pour déterminer la nature des ions, leurs flux et leurs énergies. Après exposition du SiN au plasma d’hélium, les caractérisations de surface (FTIR, SIMS) indiquent premièrement que la composition chimique du SiN est inchangée. De plus, la bonne corrélation entre les vitesses de gravure en HF avec les simulations de l’implantation des ions sous SRIM permet de conclure que l’augmentation de la vitesse de gravure est due aux dégâts induits par les ions dans le matériau. Après exposition au plasma d’hydrogène, la vitesse de gravure du SiN en HF dépend essentiellement de la concentration en hydrogène dans le matériau. Une synergie a lieu entre les radicaux H du plasma et le bombardement ionique : les ions créent des liaisons pendantes qui sont indispensables à la formation de liaisons Si-H et N-H par les radicaux. En outre, nous montrons que le temps de plasma de H2 et la dose d’ions ont une importance capitale dans la formation de la couche modifiée qui n’atteint parfois un état stationnaire qu’au bout d’un temps relativement longTo fabricate 22 nm FDSOI and 10 nm 3D FinFET transistors, ultrathin layers of several nanometers thickness must be etched without damaging the under layer, which can no longer be managed using processes based on high density continuous plasmas. To meet those new challenges, we study in this thesis a new etching technology where the surface of the material is modified under plasma exposure and then removed chemically selectively with respect to the non modified material. We focus here on the understanding of the modification of the SiN material induced by H2 and He plasmas, followed by a chemical etching in HF aqueous solution. First, a protective coating is developed to prevent the contamination of the substrate and the degradation of the wall. Diagnostics in H2 and He plasmas were then carried out to determine the nature of the ions, their fluxes and their energies. After He plasma exposure of the SiN, surface characterizations (FTIR, SIMS) first show that the SiN chemical composition is unchanged. Moreover, the good correlation between the etch rates in HF and the ion implantation profiles calculated by SRIM allows to conclude the increase of the etch rate is due to the ion-induced damages on the material. After H2 plasma exposure, the etch rate of SiN in HF mainly depends on the hydrogen concentration of the film. A synergetic effect occurs between H radicals and the ionic bombardment: the ions induce dangling bonds which are unavoidable to form Si-H and N-H bonds with the radicals. In addition, we show the plasma exposure time and the ion dose play a key role in the formation of the modified layer who sometimes only reaches a steady state after a relatively long time
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Giraldez, Douglas Cavalli. "Ressonância Eletromagnética em Cavidades Toroidais - Teoria e Experiência." Universidade de São Paulo, 1997. http://www.teses.usp.br/teses/disponiveis/43/43131/tde-04122013-183817/.
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Este trabalho procura caracterizar uma cavidade eletromagnética ressonante toroidal teórica e experimentalmente. Do ponto de vista teórico, foi obtida a relação de dispersão para as auto-frequências da cavidade resolvendo as equações de Maxwell usando teoria de perturbação. Duas soluções em ordem zero foram obtidas: uma em termos de funções hipergeométricas e outra em termos de uma série de Frobenius. Os resultados foram comparados com a literatura. Baseado nestes autovalores calculados foi projetado e construído um toróide em cobre, com secção transversal circular e razão de aspecto 1,25 (R IND.0=0.125m e R IND.0=0.100m). As medidas experimentais realizadas incluem as auto-frequências e seus respectivos índices de mérito. Pelo que se sabe, estas medidas foram as primeiras feitas num toróide. Os dados experimentais também foram comparados com os resultados teóricos, permitindo estabelecer qual dos tratamentos e mais compatível com a realidade e fornecendo elementos para um aprimoramento da teoria.Electromagnetic resonances in a toroidal cavity are studied both theoretically and experimentally. In the theory dispersion relation is obtained solving Maxwells equations in the cavity using perturbation theory, as in the literature, but with two different expansions which keep the singularity for unit aspect ratio. The results are obtained in zeroth order, including teroidal effects, in terms of Frobenius series and in terms of hypergeometric functions for which the values of the eigenfrequencies can be calculated. Based on these results, a toroidal cavity in copper was constructed with aspect ratio 1.25 (R IND.0=0.125m e R IND.0=0.100m) and circular cross section. In the experiment the eigenfrequenceis and quality factor Q are measured. These measurements are the first realized in a toroidal cavity. The experimental measurements are compared with the theoretical results, establishing the better approach and indicating new direction to the theory.
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Keiter, Paul A. "Experimental investigation of ion temperature anisotropy driven instabilities in a high beta plasma." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=995.
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Thesis (Ph. D.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains iv, 131 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 127-131).
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AMORIM, L. S. "Efeito Casimir em Placas de Plasma e a Energia de Condensação do Supercondutor do Tipo (Hg, Pb) Ba2-xSrxCa2Cu3O8+δ." Universidade Federal do Espírito Santo, 2010. http://repositorio.ufes.br/handle/10/7417.
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Previous issue date: 2010-06-08Neste trabalho é apresentada uma descrição do comportamento da temperatura crítica (Tc ) em supercondutores do tipo (Hg, Pb ) Ba2-x Srx Ca2 Cu3 O8+δ (Hg-1223). Aqui é sugerido que energia de condensação do supercondutor se dá pela energia de Casimir dos planos de CuO, considerando que estes sejam placas finas de plasma. A partir dessa hipótese chega-se a uma equação para a temperatura de transição que depende de variáveis da estrutura cristalina do supercondutor, bem como de constantes universais, e dentre essas variáveis, está o parâmetro de correção de massa efetivados pares de Cooper (α ). O objetivo aqui visado é obter uma aproximação de Tc para a família cerâmica supracitada em comparação a dados experimentais, e com valores de α arbitrariamente ajustados, mas de forma consistente e plausível.
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Sedghinasab, Ahad. "Experimental deterimination of argon atomic transition probabilities using non-LTE diagnostics." Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/17969.
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Campos, Edevaldo Donizetti de. "Geração e deteção de ondas de Langmuir em um plasma quiescente confinado por campo multi-dipolo magnético." Instituto Tecnológico de Aeronáutica, 1991. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=1843.
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Panousis, Emmanouïl. "Réalisation et optimisation d'un réacteur plasma froid fonctionnant à pression atmosphérique : application aux traitements de surfaces." Pau, 2006. http://www.theses.fr/2006PAUU3027.
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Le travail porte sur l'étude d'un plasma d'azote issu d'une décharge à barrière diélectrique à la pression atmosphérique dans un double but : une meilleure compréhension des mécanismes physico-chimiques gouvernant une telle décharge et son application au traitement de surface de métaux. Ici, le traitement s'effectue dans des conditions de post-décharge spatiale. Ainsi les produits de la décharge (principalement les espèces actives) sont acheminés en dehors de l'espace inter-électrodes. Cette configuration permet de traiter des pièces de grandes dimensions ou présentant des parties concaves, et d'envisager un procédé industriel en défilé. Les matériaux étudiés sont les alliages métalliques Al-2024 et TiA6V4, Le but du traitement est de rendre compatible les surfaces avec des applications de collage et de peinture. Ce travail est dirigé suivant 3 axes principaux : - Etude théorique de la décharge à barrière diélectrique par la modélisation et la simulation numérique : les résultats ici obtenus décrivent de façon qualitative le comportement électrodynamique de la décharge, permettant également d'estimer son efficacité à produire des espèces actives. - Etude expérimentale de la DBD et de la post-décharge. Les mesures électriques ont été employées pour l'étude comparative des deux réacteurs DBD utilisés. Puis, le diagnostic optique a permis d'identifier une part importante des espèces produites pendant la DBD et de "suivre" leur trajet dans la post-décharge en flux, dans deux modes distincts de fonctionnement (sortie libre ou guidage par un tube de quartz). Les mécanismes réactionnels dominants ont été identifiés et étudiés. - Application de la DBD au traitement des surfaces métalliques en conditions de post-décharge spatiale. Il a été constaté, par des moyens macroscopiques mais aussi microscopiques de caractérisation de la surface, que le traitement effectue un nettoyage de la contamination organique de la surface mais aussi une désoxydation partielleA dielectric barrier discharge (DBD) in Nitrogen at atmospheric pressure was the object of this work. The aim was primarily to gain insight to the physico-chemical mechanisms governing such a discharge and to also apply this configuration to the surface treatment of metals. Here, the surface treatment takes place in spatial afterglow conditions. The discharge products (active species in particular) are blown out of the inter-electrode space due to the special plasma reactors' geometry and the high gas flow. This enables the treatment of large areas and hollow objects and could easily be used in an industrial production line. The surfaces of Al-2024 and TiA6V4 metal alloys were treated during this work in an effort to render them compatible to applications involving adhesion. This work is thus composed of 3 main parts: - Numerical modeling of the DBD: results here obtained permit to qualitatively describe the discharge's electrodynamical behavior and estimate its yield in the production of active species. - Experimental study of the DBD and the afterglow: electrical diagnostic techniques were used in order to compare the two reactors studied. Optical diagnostics were then applied that helped identify the active species produced by the DBD and “follow” them in the flowing afterglow in two different configurations: the unguided and the quartz tube guided afterglow. The dominant physico-chemical mechanisms for the active species were thus identified for these conditions. - Application of the DBD in the treatment of metallic surfaces in afterglow conditions: By macroscopic and microscopic means of surface characterization it was observed that the DBD flowing afterglow were studied induces a cleaning of organic contaminants of the surface as well a possible partial de-oxidation
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Nagai, Mikio, Masaru Hori, and Toshio Goto. "Properties of atmospheric pressure plasmas with microwave excitations for plasma processing." American Institute of Physics, 2005. http://hdl.handle.net/2237/7072.
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Armengol, Jan Mateu 1988. "Estudo numérico de crescimento de gelo poroso entre placas planas paralelas." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265814.
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Orientador: Carlos Teofilo Salinas SedanoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Neste trabalho é apresentado um modelo para a formação de gelo poroso entre placas planas paralelas baseado em um novo tratamento bidimensional da taxa de crescimento. O modelo considera as equações de transporte de quantidade de movimento, energia e massa. Para a resolução do modelo, as equações são discretizadas usando o método de volumes finitos em um domínio bidimensional composto por ar e gelo poroso. A interface móvel ar-gelo é tratada utilizando a formulação de malha fixa. O domínio computacional inclui a região frontal das placas planas com a finalidade de estudar o crescimento do gelo poroso nessa região. O código numérico é verificado por partes de acordo com artigos de referência na literatura e o modelo é validado com dados experimentais. Os dados experimentais, reportando temperatura e crescimento de forma locais, coincidem com os resultados numéricos com um erro relativo inferior a 10 \% para o caso intermediário de taxa de umidade
Abstract: In this study, a frost formation model is presented based on a new two-dimensional approach for the growth rate. For modeling the frost formation over parallel cold plates, the basic transport equations of mass, energy and momentum have been discretized using the finite volume method in a two-dimensional domain in which air and frost are considered. A volume tracking method employing a fixed grid formulation is used to deal with the air-frost moving boundary. An extended domain in the inlet boundary has been considered in order to study the frost formation in the leading edge of the plate. The numerical code is gradually verified using benchmarking references. The numerical results have been validated against experimental data in which frost growth and temperature as a function of time are reported as local values. The model predictions of the frost thickness as a function of time agree with the experimental data within 10 \% of deviation for the case of intermediate humidity ratio
Mestrado
Termica e Fluidos
Mestre em Engenharia Mecânica
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Kawamura, Gakushi. "Gyrokinetic Theory for Peripheral Plasmas and its Application to Plasma Sheath." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/57265.
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Winters, Caroline. "Laser Diagnostics of Reacting Molecular Plasmas for Plasma Assisted Combustion Applications." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503306596261748.
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Surdu-Bob, Carmen Cristina. "Surface : plasma interactions in GaAs subjected to capacitively coupled RF plasmas." Thesis, Aston University, 2002. http://publications.aston.ac.uk/8000/.
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Surface compositional changes in GaAs due to RF plasmas of different gases have been investigated by XPS and etch rates were measured using AFM. Angular Resolved XPS (ARXPS) was also employed for depth analysis of the composition of the surface layers. An important role in this study was determination of oxide thickness using XPS data. The study of surface - plasma interaction was undertaken by correlating results of surface analysis with plasma diagnosis. Different experiments were designed to accurately measure the BEs associated with the Ga 3d, Ga 2P3/2 and LMM peaks using XPS analysis and propose identification in terms of the oxides of GaAs. Along with GaAs wafers, some reference compounds such as metallic Ga and Ga2O3 powder were used. A separate study aiming the identification of the GaAs surface oxides formed on the GaAs surface during and after plasma processing was undertaken. Surface compositional changes after plasma treatment, prior to surface analysis are considered, with particular reference to the oxides formed in the air on the activated surface. Samples exposed to ambient air for different periods of time and also to pure oxygen were analysed. Models of surface processes were proposed for explanation of the stoichiometry changes observed with the inert and reactive plasmas used. In order to help with the understanding of the mechanisms responsible for surface effects during plasma treatment, computer simulation using SRIM code was also undertaken. Based on simulation and experimental results, models of surface phenomena are proposed. Discussion of the experimental and simulated results is made in accordance with current theories and published results of different authors. The experimental errors introduced by impurities and also by data acquisition and processing are also evaluated.
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Moser, Matthew A. "Micro-and pulsed-plasmas fine tuning plasma energies for chemical analysis /." Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2534.
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Thesis (Ph. D.)--West Virginia University, 2002.Title from document title page. Document formatted into pages; contains ix, 99 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
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Nascimento, Fellype do 1980. "Obtenção de temperaturas e densidades de elétrons em plasmas de Tokamaks através de espectroscopia no visível de emissões de impurezas." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278079.
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Orientadores: Munemasa Machida, José Helder Facundo SeveroTese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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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
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Liu, Jingjing. "Generation and characterisation of cold atmospheric liquid-containing plasmas." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/7761.
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This thesis presents an experimental study of non-thermal atmospheric pressure gas plasmas in presence of liquid as an efficient source of transient and reactive species to initiate chemical reactions necessary for many important applications. Two types of liquid-containing plasmas are considered: discharges formed between a needle electrode and a liquid electrode, and plasma jets formed in a water vapour flow mixed in helium or argon gas. Two plasma modes (the pulsed and the continuous mode) are observed in the needle-to-liquid plasma. A comparative study of the needle-to-liquid plasma in the continuous mode with DC and AC excitations reveals that the plasmas are glow discharges, and AC excited plasmas have the highest energy efficiency. A study of helium/water vapour plasma jet shows that “plasma bullets” are formed even with water vapour in the gas mixture, but become quenched when the moist helium flow rate is above 300sccm (~1800ppm water concentration). Moderate amount of water vapour (~250ppm water concentration) is beneficial for active species production mainly due to the high electron density. Hydrogen peroxide production in saline solution with three different plasma sources is investigated due to the importance of H2O2 in several important applications. Long lifetime of H2O2 in the liquid after plasma treatment indicates an exciting possibility of plasma pharmacy.
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Lin, Jiashu. "La formation et le transport des particules dans le plasma froid." Thesis, Orléans, 2020. http://www.theses.fr/2020ORLE3029.
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Les plasma poudreux sont des plasmas qui contiennent des particules solides dont les tailles vont quelques nanomètres à quelques dizaines de micromètres. La présence de ces particules solides, dans les plasmas, a été découverte dans les procédés de l'industrie de microélectronique. Les particules dans le plasma étaint considérées comme la source principale de la contamination de ces procédés. Les premiers travaux de recherche était focalisées sur les méthodes et moyens de les éliminer et d'empêcher leur formation. Suite à l'identification des différentes phase de formation et la découverte de la structure cristalline des nanoparticules qui se forment dans la première phase des applications très prometteuses ont commencé à se développer dans différents domaines tels que le photovoltaïque, la nanoélectronique etc., Ceci a donné une nouvelle impulsion aux activités de recherches sur les propriétés du plasma poudreux ont attiré l'attention de plus en plus de chercheurs à travers le monde.Les plasmas poudreux sont des plasmas qui contiennent des particules solides dont les tailles vont de quelques nanomètres à quelques dizaines de micromètres. La présence de ces particules solides, dans les plasmas, a été découverte dans les procédés de l'industrie de microélectronique. Les particules dans le plasma étaient considérées comme la source principale de la contamination de ces procédés. Les premiers travaux de recherche étaient focalisées sur les méthodes et moyens deles éliminer et d’empêcher leur formation. Suite à l’identification des différentes phases de formation et la découverte de la structure cristalline des nanoparticules qui se forment dans la première phase des applications très prometteuses ont commencé à se développer dans différents domaines tels que le photovoltaïque la nanoélectronique etc…, Ceci a donné une nouvelle impulsion aux activités de recherches sur les propriétés du plasma poudreux et ont attiré l’attention de plus en plus de chercheurs à travers le monde.Les travaux de recherche, entrant dans le cadre de cette thèse, sur les plasmas poudreux, ont été focalisés essentiellement sur le contrôle de la formation des particules solides et leur transport dans le plasma. Par conséquent, cette thèse est composée par deux parties, la première concerne la formation des particules en phase gazeuse dans le plasma et la deuxième traitera du comportement et du transport du nuage dense de particules dans le plasma. Ces travaux ont été effectués au sein du laboratoire GRMI (Université d’Orléans, France) et du Département d’électronique du Kyoto Institute of technology (Japon), respectivement, dans le cadre d’une co-tutelle.Les travaux sur la formation des particules a été réalisée dans un plasma RF généré dans un mélange gazeux composé d’Argon (Ar, 98%) et d’Acétylène (C2H2, 2%). Le processus de formation des particules s’effectue en trois étapes: la nucléation (phase chimique), l'agglomération, et la croissance par dépôt radicalaire sur la surface des particules. Nous sommes intéressés à l'étape de nucléation. L'influence de la puissance, la pression et la température des gaz sur le temps de nucléation est étudiée. L'évolution temporelle de la tension d'auto polarisation de la décharge est utilisée comme un indice pour détecter la fin de l'étape de nucléation. Les résultats montrent que le temps de nucléation augment avec l'augmentation de la température mais diminue avec celle de la puissance et de la pression. Cela dit, plus la température est basse, la puissance et la pression sont élevées, plus la phase de nucléation est rapide. La dépendance de la nucléation de la température est expliquée par le mécanisme de la relaxation de l’excitation translationnelle-vibrationnelle des molécules du gaz précurseur. En effet l’énergie d’excitation vibrationnelle joue le rôle d’énergie d’activation pour les réactions chimiques ayant lieu lors de cette phase. Par contre, celles sur la puissance et la pression, elles sont expliquéThis thesis studies the dust particles in plasmas. It consists of two parts. The first part is the formation of dust particles, that is to study how the dust particles are generated from the reactive gas in the plasmas. The second part is the transport behaviour of dust particles, that is to study how the dust particles act in the plasmas.In the part of the formation of dust particles, carbon dust particles are generated in the plasmas. It is known that the formation process of dust particles in plasmas can be determined by 3 steps: nucleation, agglomeration and surface grow. The nucleation step is focused. The results of experiments show that the nucleation process occurs faster in higher power, higher pressure and lower temperature. The dependency of the nucleation time on the temperature is explained by the vibration-transition energy relaxation mechanism, and that on the RF power and pressure is explained by the ratio of the charge and diffusion time of the small dust particles.In the part of the transport behaviours of dust particles, industrially fabricated particles with determined size are injected into Ar plasmas. The particles in the plasmas are observed by laser scattering with a CCD camera. The diagnostics of plasma are performed by a double langmuir probe. Pulse-time modulation to the Ar RF plasmas is studied to be a factor to influence and to control the transport of dust particles. Particles of mono-dispersed size are firstly studied in the plasmas. It is shown that the levitating positions and falling down processes can be controlled by the RF power and pulse-time modulation. Secondly, two sizes particles are injected into the plasma at same time. The different transport behaviours, as like the segmentation of levitation and different timing of falling down basis on their size, are observed. Particles of mixture sizes can be separated one size particles from other sizes. The mechanisms of transport behaviours of the dust particles are investigated by the combination of the diagnostic of plasma parameters (electron temperature and ion density in principle) by the double langmuir probe and calculation of the forces acting on the dust particles. Calculation methods adjusting to the specific experiment setup are established. The calculation results have a good agreement with that of the experiments
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Fukumoto, Hiroshi. "Model Analysis of Plasma-Surface Interactions during Silicon Oxide Etching in Fluorocarbon Plasmas." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/158076.
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Meige, Albert. "Simulations numériques de plasmas basse pression : applications aux doubles couches." Toulouse 3, 2006. http://www.theses.fr/2006TOU30203.
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Un modèle particle-in-cell / Monte Carlo collisions (pic/mcc) unidimensionnel est utilsé pour simuler un plasma inductif. Un champ électrique radiofréquence (rf) est utilisé pour modéliser le chauffage inductif. L’amplitude du champ est non-uniforme et sa direction perpendiculaire à celle du déplacement des électrons. Ce modèle de plasma inductif permet de confirmer de récents résultats expérimentaux démontrant la possibilité de former des doubles couches électriques au sein de plasmas sans courant. Les doubles couches étudiées par le passé, aussi bien numériquement qu’expérimentalement, ont toujours été imposées par différence de potentiel ou en forçant un courant électrique dans le plasma. C’est en ce sens que les résultats présentés ici diffèrent de ceux précédemment reportés. La simulation prédit la formation d’un faisceau d’ions supersoniques résultant des ions accélèrés par le saut de potentiel de la double couche. L’existence de ce faisceau d’ions supersoniques est confirmée par fluorescence induite par laser (nonperturbative laser-induced fluorescence). La simulation montre aussi qu’à basse pression, lorsque le libre parcours moyen des électrons est du même ordre de grandeur ou plus grand que le système, la fonction de distribution en énergie des électrons (eedf) est quasi-Maxwellienne, à l’exception de sa queue, dépeuplée pour des énergies supérieures au potentiel plasma. Ce dépeuplement est principalement dû à la perte aux parois des électrons les plus rapides. Un nouveau schéma de simulation hybride (ions particulaires et électrons particulaires et Boltzmann), permettant de simuler des plasmas hautes pressions et hautes densités, en des temps de calculs relativement faibles, est proposé. Les résultats obtenus avec ce modèle hybride “amélioré” sont bien plus proches de ceux d’une simulation pic, que le sont ceux d’une simulation hybride classique. Ce modèle est appliqué à la simulation de décharges électronégatives et confirme des résultats expérimentaux démontrant la possibilité de formation de doubles couches propagatives. En particulier, les paramètres critiques contrôllant cette formation dans la simulation corroborent ceux de l’expérienceInductive plasmas are simulated by using a one-dimensional particle-in-cell simulation including Monte Carlo collision techniques (pic/mcc). To model inductive heating, a non-uniform radio-frequency (rf) electric field, perpendicular to the electron motion is included into the classical particle-in-cell scheme. The inductive plasma pic simulation is used to confirm recent experimental results that electric double layers can form in current-free plasmas. These results differ from previous experimental or simulation systems where the double layers are driven by a current or by imposed potential differences. The formation of a super-sonic ion beam, resulting from the ions accelerated through the potential drop of the double layer and predicted by the pic simulation is confirmed with nonperturbative laser-induced fluorescence measurements of ion flow. It is shown that at low pressure, where the electron mean free path is of the order of, or greater than the system length, the electron energy distribution function (eedf) is close to Maxwellian, except for its tail which is depleted at energies higher than the plasma potential. Evidence supporting that this depletion is mostly due to the high-energy electrons escaping to the walls is given. .
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Brichon, Paulin. "Vers une gravure plasma de précision nanométrique : simulations de dynamique moléculaire en chimie Si-Cl." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GRENT010/document.
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Ce travail de thèse aborde le problème de la gravure de matériaux ultraminces pour la réalisation de nouvelles générations de transistors (FDSOI, FinFET) dans les dispositifs nanoélectroniques avancés. Ces transistors doivent être gravés avec une précision nanométrique pour ne pas endommager les propriétés électroniques des couches actives. Afin d'atteindre une telle précision, les dommages surfaciques et l'épaisseur des couches réactives formées lors de l'exposition plasma doivent être maintenus en-deçà du nanomètre, véritable défi auquel les plasmas ICP continus ne sont plus à même de répondre. Pour assister le développement de nouveaux procédés de gravure, des simulations de dynamique moléculaire ont été développées afin étudier l'influence de nouvelles technologies plasma (plasmas pulsés, plasma basse Te, gaz pulsés) sur les interactions entre silicium et plasmas chlorés. Les simulations montrent que l'énergie ionique (Eion) est le paramètre numéro un pour contrôler la gravure de couches de Si ultraminces, une diminution de l'énergie réduisant à la fois l'épaisseur de couche endommagée SiClx et le taux de gravure. Le rapport du flux de neutres sur flux d'ions (Γ) est le 2nd paramètre clé : son augmentation entraîne une diminution sensible l'épaisseur de couche perturbée tout en augmentant le taux de gravure. Quantitativement, cette étude montre que des plasmas caractérisés par de faibles énergies ioniques (< 15 eV) ou des rapports Γ importants (⩾ 1000) permettre d'obtenir des couches réactives d'épaisseur sub-nanométrique (cf. plasmas basse Te ou synchronisés pulsés). En mode "bias pulsé", les simulations montrent que pour une valeur Vbias donnée, pulser le bias permet de diminuer à la fois l'épaisseur de couche réactive et le taux de gravure. Cet effet est d'autant plus marqué que le rapport de cycle DC est faible, ce qui élargit la fenêtre des paramètres opératoires. Pour contrôler la gravure, une autre solution pourrait consister à contrôler l'épaisseur des couches réactives de manière dynamique. Inspiré de l'ALE (Atomic Layer Etching), ce nouveau concept consiste à pulser rapidement et alternativement différents gaz pour décomposer le procédé de gravure en cycles répétitifs de deux étapes plasma distinctes. La 1ère étape vise à limiter la formation de la couche mixte à 1nm d'épaisseur dans un plasma réactif (Cl2) en optimisant le temps d'injection du gaz; la 2nde étape vise à graver la couche ainsi formée dans un plasma de gaz rare (Ar, Xe) sans endommager le matériau sous-jacent. Nos simulations confirment la faisabilité et la répétabilité d'un tel conceptThis thesis focuses on technological challenges associated with the etching of ultrathin materials used for new generations of transistors (FDSOI, FinFET) in advanced nanoelectronics devices. These transistors must be etched with a nanometric precision in order to preserve the electronic properties of active layers. To reach such a precision, plasma-induced damage and reactive layers thicknesses formed during the etch must remain below 1nm, a challenge which cannot be addressed by continuous-waves ICP plasmas. To assist the development of new etching processes, molecular dynamics simulations have been developed to study the influence of new plasma technologies (pulsed plasmas, low-Te plasmas, gaz pulsing) on interactions between silicon and chlorine plasmas. Simulations show that the key parameter to control the etching of ultrathin Si layers is the ion energy (Eion), which lowers both the SiClx damaged layer thickness and the etch rate when it is decreased. The neutral-to-ion flux ratio (Γ) is the second key parameter: its increase strongly reduces the reactive layer thickness while the etch rate grows. Quantitatively, this study shows that plasmas with low ion energies (< 15 eV) and high Γ ratios (⩾ 1000) allow to obtain sub-nanometer thick reactive layers (cf. low-Te or synchronized pulsed plasmas). In « pulsed bias » mode, simulations show that for a given Vbias value, pulsing the bias decreases both the reactive layer thickness and the etch rate. This effect is stronger at low duty cycle DC, which can improve the control of the etching process. To control the etching of ultrathin films, another solution may be to control dynamically the reactive layers formation. Inspired from ALE (Atomic Layer Etching) principle, this new concept consists in pulsing quickly and alternatively several gases to divide the etching process into repetitive cycles of two distinct plasma steps. The first step aims to limit the mixed layer formation at 1nm in a reactive (Cl2) plasma by optimizing the gas injection time; the 2nd step aims to remove the so-formed layer in a noble gas plasma (Ar, Xe) without damaging the material below. Our simulations confirm the feasibility and the repeatability of such a concept
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Gangoli, Shailesh Pradeep Gutsol Alexander Fridman Alexander A. "Experimental and modeling study of warm plasmas and their applications /." Philadelphia, Pa. : Drexel University, 2007. http://hdl.handle.net/1860/1864.
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Gangoli, Shailesh Pradeep Gutsol Alexander Fridman Alexander A. "Design and preliminary characterization of the magnetically stabilized gliding arc discharge /." Philadelphia, Pa. : Drexel University, 2007. http://hdl.handle.net/1860/1860.
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Raji, Rufai Odutayo. "Nonlinear low frequency wave phenomena in space plasmas." Thesis, University of the Western Cape, 2013. http://hdl.handle.net/11394/4036.
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Philosophiae Doctor - PhDIn this thesis, using multispecies fluid plasma models, nonlinear electrostatic solitary wave fluctuations will be investigated in magnetized plasmas. The different models used for the investigation will be guided by the satellite observations in different regions of the Earth magnetosphere. These investigations will enable us to attempt theoretical explanations for the nonlinear potential structures observed in the satellite data. Multispecies plasma consisting of cool and hot electrons with Maxwellian distributions and fluid ions will be considered to study low frequency solitons. The ions will be considered as magnetized. The study will be extended to include magnetized oxygen ions. The model will be modified for regions of the magnetosphere consisting of two ions having Maxwellian distributions and magnetized electrons. The nonthermal distributions of energetic hot electrons and the Maxwellian distributions of cool electrons with magnetized cold ions fluid will also be considered. For all the models, the effect of ion and electron densities, temperatures, magnetic field strength and propagation angle will be studied during the investigation of soliton structures. In all the above mentioned studies, arbitrary amplitude theory is carried out by the Sagdeev pseudo-potential method. Further investigations on the charateristics and existence domains of the solitons is found both analytically and numerically, using satellite data where applicable
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COURTEILLE, CATHERINE. "Etude d'une grande source multipolaire hybride d'ions negatifs d'hydrogene et de deuterium. Developpement des techniques de mesures par photodetachement laser." Caen, 1993. http://www.theses.fr/1993CAEN2020.
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En analysant l'evolution du rapport de la densite des ions negatifs sur celle des electrons, en fonction du courant de decharge, pour differentes pressions, nous avons pu mettre en evidence la forte dependance de ce terme en fonction de la temperature electronique. Les observations des signaux de photodetachement, observes au centre de la source et dans la region proche de l'extracteur, nous ont conduit a ameliorer la comprehension de ce signal. Nous en avons conclu que le signal de photodetachement est la superposition de deux signaux: un signal capacitif de courte duree plus un signal conductif beaucoup plus long. Nous avons mis en evidence la dependance du signal capacitif en fonction de la densite des ions negatifs, et developpe une nouvelle technique de mesure de la temperature des ions negatifs, par sondes capacitives
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Couëdel, Lénaïc Gaël Hervé Fabien. "Nanoparticle formation and dynamics in a complex (dusty) plasma : from the plasma ignition to the afterglow." Connect to full text, 2008. http://hdl.handle.net/2123/4121.
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Thesis (Ph. D.)--University of Sydney, 2009.Includes graphs and tables. Cotutelle thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Complex Plasma Laboratory, School of Physics, Faculty of Science, University of Sydney and the degree of Docteur de l'Université Orléans. Title from title screen (viewed May 5, 2009) Degree awarded 2009; thesis submitted 2008. Includes bibliographical references. Also available in print form.
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Blais, Alexandre. "Modélisation tridimensionnelle stationnaire d'un arc transféré influencé par un champ magnétique externe." Sherbrooke : Université de Sherbrooke, 2001.
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Gallagher, Michael J. Fridman Alexander A. "Partial oxidation and autothermal reforming of heavy hydrocarbon fuels with non-equilibrium gliding arc plasma for fuel cell applications /." Philadelphia, Pa. : Drexel University, 2010. http://hdl.handle.net/1860/3199.
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Cremonez, Victor Gonçalves. "Estufa solar para secagem de madeira serrada : uso de placas planas fotovoltaicas." reponame:Repositório Institucional da UFPR, 2016. http://hdl.handle.net/1884/45775.
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Orientador : Prof. Dr. Ricardo Jorge KlitzkeCoorientador : Prof. Dr. Márcio Pereira da Rocha
Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Agrárias, Programa de Pós-Graduação em Engenharia Florestal. Defesa: Curitiba, 24/02/2016
Inclui referências : f. 89-101
Área de concentração : Tecnologia e utilização de produtos florestais
Resumo: A secagem da madeira é um processo essencial para se agregar valor a esse produto e o método mais utilizado para esse fim é a secagem em câmara convencional. Entretanto, essa tecnologia possui um alto custo de implementação e em energia. O emprego de técnicas que diminuam esses valores são de grande importância tanto para a indústria, quanto para pequenos produtores. Considerando o exposto, o presente trabalho teve por objetivo avaliar a eficiência de uma estufa solar para secagem de madeira serrada, aferindo o uso de placas fotovoltaicas planas, visando máximo rendimento da radiação solar e do equipamento. Para isso, foi construída uma estufa solar do tipo greenhouse com capacidade aproximada de 1m³ de madeira serrada e com ventilação forçada. Com esse equipamento foram secas tábuas de Eucalyptus spp de 2,5 cm de espessura e comparadas com a secagem de tábuas em câmara convencional. Como análise preliminar da madeira foi avaliada a massa específica e o teor de umidade inicial, sendo antes e após o processo de secagem avaliados os parâmetros de qualidade e de secagem da madeira. Para a análise das variáveis ambientais envolvidas na estufa solar, foram utilizados dados de temperatura e umidade relativa do ar dentro e fora dela, e dados de radiação solar, calculando-se a eficiência térmica dos coletores. Paralelamente, foi realizado um estudo da eficiência de placas fotovoltaicas planas de silício policristalino e foi avaliada a viabilidade técnica desse elemento para gerar energia ao ventilador da estufa solar. O tempo de secagem solar foi quatro vezes menor que a secagem convencional. A Estufa solar mostrou-se eficiente termicamente, obtendo temperaturas próximas as ideais para secagem de eucaliptos nesse método. As variáveis ambientais demonstraram que o ponto crítico na secagem solar no dia é durante as 15 horas. As placas fotovoltaicas apresentaram viabilidade técnica para aplicação no protótipo. A secagem solar apresentou uma qualidade final melhor que a secagem convencional e um teor de umidade final similar, mostrando-se competitiva no mercado. Palavras-chave: Estufa solar. Secagem solar. Eficiência térmica. Eucalyptus spp.
Abstract: The wood drying is an essential process to add value to this product and the most widespread method used for this purpose is a kiln dryer, however, there is a high cost of energy for this technology and techniques that reduce these values are of great importance for the industry and for smaller producers as well. Considering these facts, this present study aimed to evaluate the efficiency of a greenhouse for lumber drying, checking the use of flat photovoltaic panels, seeking maximum efficiency of solar radiation and of the equipment. In order to do so, a solar kiln was built with approximate capacity of 1m³ and with forced ventilation. With this equipment Eucalyptus spp. boards with 2.5 cm thickness were dried and compared with boards dried with a standard kiln dryer. As a preliminary analysis of the wood, it was measured the specific gravity and the initial moisture content, with quality parameters of the wood drying being evaluated after and before the process. For the analysis of the environmental variables involved in solar drying it was used temperature and relative humidity inside and outside, and data of solar radiation, calculating the thermal efficiency of the collectors. In parallel, it was conducted a study of the efficiency of flat photovoltaic panels of polycrystalline silicon and it was verified the technical viability of this element to generate power to the fan of the solar drying. The solar drying time was four times less than conventional drying. The solar kiln was efficient thermally, obtaining temperatures near ideal for drying eucalyptus in this method. The environmental variables showed that the critical point in the solar drying is around 3 PM. The photovoltaics panels presented technical viability for use in the prototype. Solar drying presented a better final quality than conventional drying and a similar final moisture content, being competitive in the market. Key-words: Solar kiln. Solar drying. Thermal efficiency. Eucalyptus spp.
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Tatsch, Peter Jürgen 1949. "Estudo da viabilidade da oxidação do silicio por plasma em reator planar." [s.n.], 1988. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260389.
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Orientador : Edmundo da Silva BragaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica
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Resumo: Neste trabalho é apresentado um estudo da viabilidade da oxidação do silício por plasma, em reator planar, como prcesso de baixa temperatura para a fabricação de circuitos integrados. No capítulo inicial coloca-se o contexto do trabalho assim como a sua proposiçao. No segundo capítulo apresenta-se uma descrição concisa da fenomenologia e do rnodelamento atinentes ao plasma utilizados no desenvolvimento do trabalho. No terceiro capítulo descreve-se sinteticamente a estrutura do sistema silício-dióxido de silício. O quarto capítulo versa sobre o projeto do reator planar utilizado e sobre os procedimentos experimentais aplicados na , preparação das amostras e na sua caracterização. As amostras foram oxidadas em plasmas de oxigênio e misturas de oxigênio e tetracloreto de carbono. O plasma foi analisado por espectrometria óptica e os filmes de óxido foram estudados através de medidas C-V de alta frequência, elipsometria e taxa de corrosão em reagente P. No último capítulo apresentam-se os resultados experimentais e sua análise. Obtiveram-se densidades efetivas de carga na faixa de 10 11 cm-2 e taxas de oxidação entre 0,4 nm min-l e 1,3 nm min-l, fortemente dependentes das condições do plasma. As medidas de espectrometria óptica mostram que o oxigênio atômico é a espécie principal envolvida no mecanismo da oxidação
Abstract: Not informed.
Doutorado
Doutor em Engenharia Elétrica
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Santos, Marcio Bueno dos. "Transferência de calor no escoamento turbulento em desenvolvimento entre placas planas paralelas." Instituto Tecnológico de Aeronáutica, 1991. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=1849.
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O presente trabalho tem por finalidade a análise experimental do problema de convecção forçada entre placas paralelas no escoamento com transição laminar-turbulento, com condições assimétricas do perfil de temperatura. A determinação dos valores locais dos coeficientes de transferência de calor é obtida aplicando-se a técnica se Sublimação de Naftaleno. De acordo com a analogia entre transferência de calor e transferência de massa as condições experimentais correspondem a situação de transferência de calor onde uma das placas esta a uma temperatura uniforme e a outra é isolada. A seção de testes constitui-se de um canal retangular construido por duas laterais e uma base de duralumínio e uma tampa de acrílico, a qual simula a placa isolada. Sobre a base são instaladas as placas de naftaleno que simulam a superfície isotérmica. Na entrada da seção de testes foi montada uma contração do tipo "boca de sino" que tem por finalidade uniformizar o pérfil de velocidade. As experiências foram realizadas succionando-se ar através da seção de testes o que provoca a sublimação nas superfícies das placas da naftaleno, desgastando-as. Os coeficientes locais de transferência de calor foram obtidos empregando-se a analogia de transferência de calor e massa, medindo-se o desgaste local da placa com um apalpador numa mesa de coordenadas. O desenvolvimento simultâneo das camadas limites térmica e hidrodinâmica é estudado, e são obtidas informações sobre o número de Sherwood no desenvolvimento da camada limite laminar e da camada limite turbulenta. Os coeficientes de transferência são apresentados em forma adimensional (número de Nusselt e Sherwood) e a faixa do número de Reynolds estudada foi de 15.000 a 65.000.
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Laraia, André Bianchi. "Tratamento a plasma para melhoria na metalização de placas de circuito impresso." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/155973.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Este trabalho apresenta o desenvolvimento de um processo de tratamento com plasma para melhorar ametalização química de placas de circuito impresso (PCI). A pluma de plasma é gerada em argônio a partir da descarga de barreira dielétrica (DBD) promovida entre uma agulha cirúrgica e um cilindro usando capilar de borosilicato como dielétrico. A tensão picoa-pico aplicada foi de 5 kV, com forma de onda senoidal na frequência de 37 kHz e potência de descarga em torno de 765 mW. O substrato é um composto de fibra de vidro e resina epóxi. Com incidência perpendicular da pluma de plasma na superfície, o diâmetro da área tratada circular é de 10 mm. Desta forma, o ângulo de contato reduz de 75 ° a 45 ° com 3 s de interação entre superfície da amostra e a ponta do plasma e o ângulo atinge o mínimo de 33 ° após 180 s de tempo de tratamento. A metalização química foi feita com banhos seqüenciais de solução de paládio e finalizada com banho de solução aquosa de cobre. Testes de adesão padrão mostraram uma forte adesão das camadas de metal nas superfícies previamente tratadas com as plumas de plasma. Esta adesão melhora com o tempo de tratamento. A melhoria na metalização foi observada em superfície plana e também em furos usados para conectar diferentes camadas em PCIs. A área metalizada na superfície dos buracos é maior nos orifícios tratados. Quanto maior o tempo de tratamento, maior é essa área. Todos os resultados indicaram que a técnica de tratamento por plasma de placas de fibra de vidro melhora a sua metalização química pelo cobre, levando a uma adesão mais uniforme e eficaz do metal à superfície com um método ambientalmente amigável
This work reports the development of a plasma treatment process to improve the chemical metallization of printed circuit boards (PCB). The plasma plume is generated in argon from a dielectric barrier discharge (DBD) promoted between a surgical needle and a cylinder using a borosilicate capillary as dielectric. The applied peak-to-peak voltage was 5 kV, with sinusoidal waveform at 37 kHz frequency and power in the discharge around 765 mW. The substrate was a composite of fiberglass and epoxy resin. With perpendicular incidence of the plasma plume on the surface the diameter of the circular treated area was 10 mm. In this area the contact angle reduces from 75° to 45° with 3 s of the plasma-surface interaction and the angle reaches the minimum of 33° after 180 s of treatment time. Chemical metallization was made with sequential baths of solution of palladium and finished with bath of aqueous solution of copper. Standard adhesion tests showed a strong adhesion of the metal layer on surfaces previously treated with the plasma plumes. This adhesion improves with the treatment time. The improvement in the metallization was observed on flat surface and also in holes used to connect different layers in PCB’s. The metallized area on the surface of the holes is larger in treated holes. The longer the treatment time the larger is this area. All these results indicated that the technique of plasma treatment of fiberglass boards improves its chemical metallization by copper leading to a more uniform and effective adhesion of the metal to the surface with an environmental friendly method
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Honda, Mitsuru. "Transport simulation of tokamak plasmas including plasma rotation and radial electric field." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136227.
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