This thesis presents results on the description of plasma waves in terms of wavepackets. The wave field is decomposed into a distribution of wavepackets in a space of position, wavevector, time, and frequency. A complex structure joining each pair of Fourier conjugate variables into a single complex coordinate allows the efficient derivation of equations of motion for the phase space distribution by exploiting its analytic properties. The Wick symbol calculus, a mathematical tool generalizing many convenient properties of the Fourier transform to a local setting, is used to derive new exact phase space equations which maintain full information on the phase of the waves and include effects nonlocal in phase space such as harmonic generation. A general purpose asymptotic expansion of the Wick symbol product formula is used to treat dispersion, refraction, photon acceleration, and ponderomotive forces. Examples studied include the nonlinear Schrödinger equation, mode conversion, and the Vlasov equation. The structure of partially coherent wave fields is understood in terms of zeros in the phase space distribution caused by dislocations in its complex phase which are shown to be correlated with the field entropy. Simulations of plasma heating by crossing electron beams are understood by representing the resulting plasma waves in phase space. The local coherence properties of the beam driven Langmuir waves are studied numerically.

In this work we have studied linear wave propagation in magnetized plasmas using a fully relativistic kinetic equation of spin-1/2 particles in the long scale approximation. The linearized kinetic equation is very long and complicated, hence we worked with restricted geometries in order to simplify the calculations. The dispersion relation of the relativistic model was calculated and compared with a dispersion relation from a previous work at the semi-relativistic limit. Moreover, a new mode was discovered that survives in the zero temperature limit. The origin of the mode in the kinetic equation was discussed and derived from a non-relativistic kinetic equation from a previous work.

No description available.

Le propulseur PEGASES (Plasma Propulsion with Electronegative Gases) est un nouveau type de propulseur électrique pour la propulsion spatiale. Il utilise des ions négatifs et positifs créés par une décharge radiofréquence à couplage inductif pour générer la poussée. L’accélération électrostatique des ions est assurée par un ensemble de grilles polarisées. Un filtre magnétique est utilisé pour augmenter la quantité d'ions négatifs dans la cavité du propulseur. Le propulseur PEGASES est non seulement une source qui permet de créer un plasma d'ions négatifs à forte densité, et même un plasma d'ion-ion, mais il peut également être utilisé comme un propulseur ionique classique. Cela signifie qu'un plasma est créé dans un gaz électropositif (e.g. Xe) et que les ions positifs sont extraits et accélérés. Dans ce cas, il est nécessaire de neutraliser le plasma derrière la zone d'accélération, comme dans d'autres propulseurs ioniques. Les performances du propulseur PEGASES ont été étudiées principalement dans du xénon afin de comparer les résultats obtenus avec les propulseurs ioniques de type RIT. Le propulseur a été étudié à l'aide d'une série de sondes telles qu’une sonde de Langmuir, une sonde plane, une sonde capacitive et un RPA (pour Analyseur à Champ Retardateur). De plus, une sonde en champs croisés ExB a été développée pour mesurer la vitesse des ions quittant le propulseur ainsi que la fraction des différentes espèces ioniques présentes dans le plasma. / The PEGASES thruster (Plasma Propulsion with Electronegative Gases) is a novel type of electric thruster for space propulsion. It uses negative and positive ions produced by an inductively coupled radio frequency discharge to create the thrust by electrostatically accelerating the ions through a set of grids. A magnetic filter is used to increase the amount of negative ions in the cavity of the thruster. The PEGASES thruster is not only a source to create a strongly negative ion plasma or even an ion-ion plasma but it can also be used as a classical ion thruster. This means that a plasma is created and only the positive ions are extracted and accelerated making it necessary to neutralize the plasma behind the acceleration stage like in other ion thrusters. The performances of the PEGASES thruster have been investigated mainly in xenon in order to compare the obtained results with RIT-type ion thrusters. The thruster has been investigated with the help of a variety of probes such as a Langmuir probe, a planar probe, a capacitive probe and a RPA (Retarding Potential Analyzer). In addition, an ExB probe has been developed to measure the velocity of the ions leaving the thruster and to differentiate between the ion species present in the plasma.

Made available in DSpace on 2015-07-22T20:50:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-25 / A heparanase-1 (HPA1) é uma endo-β-glucuronidase que degrada ligações glicosídicas intrassacarídicas entre a hexosamina e ácido glucurônico de cadeias de heparam sulfato, constituintes dos proteoglicanos de matriz extracelular e superfície celular. Seu gene encontra-se localizado no cromossomo 4 humano (4q21,3). A HPA1 gera oligossacarídeos que estão envolvidos na proliferação celular, angiogênese e diferenciação celular relacionados com o desenvolvimento de tumores e metástases. A heparanase-2 (HPA2) é codificada pelo cromossomo 10q23-24. Existem três isoformas da HPA2 de 480, 534 e 592 aminoácidos. As análises dessas proteínas evidenciam que todas essas isoformas são proteínas intracelulares, associadas à membrana, contendo a porção C-terminal voltada para o citoplasma e não apresentam atividade enzimática. O presente estudo tem por objetivo identificar e quantificar a expressão de HPA1 (isoformas 50kDa e 65 kDa), e isoformas da HPA2 no plasma de pacientes com carcinoma gastrointestinal, comparando-se com a expressão em indivíduos não acometidos por neoplasia (grupo controle). As proteínas plasmáticas foram identificadas por eletroforese em gel de poliacrilamida (SDS-PAGE 10%) e transferidas para membrana Hybond-CE, que foi incubada com anticorpo primário anti-HPA1 H-80 ou anti-HPA2 C-17 e revelada com anticorpo secundário conjugado com HRP IgG peroxidase. Isoformas das heparanases foram quantificadas por densitometria (Scion Image) e confirmada por RT-PCR em tempo real. Análises estatística foram realizadas utilizando o programa SPSS 13.0 Windows (SPSS, Chicago, IL). Os resultados demosntraram que ambas isoformas da HPA1 (HPA1 50 kDa e HPA1 65 kDa) e isoformas de HPA2 encontram-se significativamente aumentadas no plasma de pacientes com carcinoma gastrointestinal, comparando-se com o grupo controle. As análises em tempo real da expressão de HPA1 e HPA2 na fração mononuclear do sangue evidenciaram aumento de expressão de HPA1 e HPA2 em pacientes com carcinoma gastrointestinal corroborando com as análises do plasma. Os resultados obtidos demonstram que tanto HPA1 como HPA2 desempenham papel fundamental na carcinogênese gastrointestinal e, portanto, entender o papel fisiológico que desempenham possa fornecer informações para desenvolvimento de possivel terapia anti-tumoral. / Heparanase-1 (HPA1) is an endo-β-glucuronidase that degrades intradisaccharides glycosidic linkage between hexosamine and glucuronic acid into heparan sulfate chains, present on extracellular matrix and surface proteoglycans. HPA1 gene is located at 4q21.3 chromossome. Oligosaccharides generated by HPA1 are involved in cell proliferation, angiogenesis and cell diferentiation related with tumor development and metastasis. Heparanase-2 (HPA2) is encoded by 10q23-24 chromossome. There are three HPA2 isoforms containing 480, 534 and 592 aminoacids. All HPA2 isoforms have shown that they are intracellular, membrane associated proteins, containing C-terminal domain to the cytoplasm and do not present enzymatic activity. The objective of the present study is to identify and quantify HPA1 (isoforms 50 kDa and 65 kDa), and HPA2 isoforms expression in the plasma of gastrointestinal carcinoma patients, compared with individuals that do not present neoplasia (control group). Plasmatic proteins were identified by polyacrilamide gel electrophoresis (10% SDS-PAGE) and transferred to Hybond-CE membrane, incubated with primary anti-HPA1 H-80 or anti-HPA2 C-17 and developed using secondary antibody conjugated with HRP IgG peroxidase. Heparanases isoforms were quantified by densitometry (Scion Image) and confirmed by real time RT-PCR. Statistic analysis were performed using SPSS 13.0 program (SPSS, Chicago, IL). The results have shown that both HPA1 isoforms (HPA1 50 kDa and HPA1 65 kDa) and HPA2 isoforms were significantly increased in gastrointestinal carcinoma patients plasma, compared with control group. Real time analysis of HPA1 and HPA2 expression in the mononuclear fraction of blood demonstrated an increase HPA1 and HPA2 expression in gastrointestinal carcinoma patients that corroborates with plasma analysis. The obtained results demonstrated that both HPA1 and HPA2 have a fundamental role in gastrointestinal carcinogenesis and, therefore, to understand their physiological function it could help the development of possible new antitumor therapies. / TEDE / BV UNIFESP: Teses e dissertações

Les micro-jets de plasma, se propageant dans un flux d'hélium entouré d'air libre, à pression atmosphérique et à température ambiante, ont attiré l'attention des chercheurs depuis une dizaine d'années. Ces micro-jets sont créés dans une décharge à barrière diélectrique alimentée par des impulsions de tension. Ils se propagent dans le flux d'hélium à l'extérieur de la DBD sous la forme d'une onde d'ionisation. Le plasma est confiné spatialement là où l'hélium est dominant, car l'ionisation de l'air nécessite un champ électrique plus important que celui présent dans le front d'ionisation. Leurs applications biomédicales sont prometteuses car ils permettent de produire des espèces réactives à quelques centimètres de distance de la DBD sans augmenter la température du gaz. Dans cette thèse, l'objectif a été de développer une meilleure compréhension de l'influence des conditions expérimentales et de la géométrie de la DBD sur les propriétés des jets de plasma. À ces fins, l'écoulement d'hélium a été étudié expérimentalement et numériquement, et des simulations sur la génération et la propagation du micro-jet de plasma ont été réalisées. / Microplasma jets propagating in a helium flow surrounded by air at ambient pressure and temperature have attracted the attention of many researchers over the past decade. These microplasma jets are ignited in a cylindrical dielectric barrier discharge (DBD) powered by impulse or sinusoidal voltage pulses with an amplitude of several kilovolts and then propagate as an ionization wave in the helium flow outside the DBD. The plasma so-generated is confined to the region where helium is the dominant species because ionization of the surrounding air requires a significantly higher electric field strength than is present at the ionization front in the plasma jet. The putative biomedical applications of microplasma jets are particularly promising because they provide a way of producing reactive oxygen and nitrogen species some centimeters downstream from the DBD without significant gas heating. The objective of the work reported in this thesis has been to develop a better understanding of the influence of the operating conditions and geometry on the properties of the plasma jets. To this end, experimental and numerical studies of the hydrodynamics of the helium flow and simulations of the generation and propagation of the microplasma jet have been carried out.

Este trabalho teve por objetivo desenvolver um processo de sinterização a plasma utilizando gaiola catódica para a sinterização de amostras de alumínio, para atmosferas de argônio, hidrogênio e nitrogênio. Avanços recentes na sinterização a plasma motivaram a investigação sobre seus benefícios para o alumínio e se a técnica de tela ativa, em particular com o uso de gaiola catódica, é capaz de contornar alguns problemas encontrados na sinterização deste material, como a presença de uma camada passiva de óxido e a expansão volumétrica após a sinterização para certos parâmetros de processo. A sinterização foi realizada em três processos: convencional, plasma direto e plasma com gaiola catódica. Para o processo convencional utilizou-se atmosferas de argônio e nitrogênio e, para os processos a plasma, utilizou-se atmosferas de argônio, hidrogênio e nitrogênio. Houve queda na densificação média após a sinterização em todos os processos. Tanto o processo a plasma direto e com gaiola catódica resultaram na menor queda de densificação. A atmosfera de nitrogênio mostrou-se a mais efetiva nos processos avaliados, indo ao encontro com o reportado na literatura consultada. Houve aparente endurecimento superficial das amostras sinterizadas a plasma direto. As amostras sinterizadas a plasma com gaiola catódica obtiveram homogeneidade nos valores de microdureza superficial e transversal entre as atmosferas, concordando com o esperado do uso desta técnica. O processo a plasma direto produziu amostras com maior rugosidade em comparação com os outros processos, não havendo influência significativa da atmosfera de sinterização neste aspecto. Foi detectada a presença de zinco na superfície de amostras provenientes do processo convencional com nitrogênio e do processo a plasma com gaiola catódica utilizando argônio e nitrogênio, sendo confirmado pela análise química. Houve formação de nitreto de alumínio apenas no processo convencional com nitrogênio. O processo a plasma com gaiola catódica mostrou-se o mais promissor por apresentar bons resultados em relação aos obtidos nos outros processos avaliados e por ser capaz de preservar a integridade superficial das amostras. É possível promover a melhora das propriedades superficiais do alumínio com o uso de gaiola catódica através de tratamentos termoquímicos concomitantes com a sinterização, tendo em vista os benefícios relatados na literatura. / This study aimed to develop a plasma sintering process using cathodic cage for sintering aluminum samples for argon, hydrogen and nitrogen atmospheres. Recent advances in plasma sintering motivated the research into its benefits for the aluminum and if the active screen technique, in particular the use of cathodic cage, can overcome some problems encountered in the sintering of this material, as the presence of a passive oxide layer and volumetric expansion after sintering for certain process parameters. Sintering was carried out in three processes: conventional, direct plasma and plasma with cathodic cage. For the conventional process was used argon and nitrogen atmospheres and for the plasma processing was used argon, hydrogen and nitrogen atmospheres. There was a decrease in average densification after sintering in all processes Both the direct plasma and cathodic cage plasma processes resulted in the smallest drop of densification. The nitrogen atmosphere proved to be the most effective in al processes evaluated, meeting with the reported in the literature. There was apparent superficial hardening of the samples sintered in direct plasma. Samples sintered in cathodic cage plasma obtained homogeneity in values of surface and cross section hardness between the atmospheres, according to the expected use of this technique. The direct plasma process produced samples with higher surface roughness compared with other processes, with no apparent influence of the atmosphere in this respect. It was detected the presence of zinc in the sample surface from the conventional process with nitrogen and cathodic cage plasma process with argon and nitrogen being confirmed by chemical analysis. The phase analysis on the sintered samples with nitrogen accused the formation of aluminum nitride for the conventional process. The cathodic cage plasma process proved to be the most promising for showing good results compared to those obtained in the other processes evaluated and to be able to preserve the surface integrity of the samples. It is possible to promote the improvement of the surface properties of aluminum with the use of active screen via thermochemical treatments concomitant with the sintering, in view of the benefits reported in the literature.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-Graduação em Química. / Made available in DSpace on 2012-10-26T09:26:17Z (GMT). No. of bitstreams: 1 303917.pdf: 2000217 bytes, checksum: 0474276782ae1fe191eba9a31bb9e2ae (MD5) / O presente trabalho enfoca o processo de degradação de três corantes azo em meio aquoso por plasma frio de descarga corona. A influência de parâmetros operacionais do sistema de trabalho, perfil cinético da degradação, efeito pós descarga, identificação de subprodutos de degradação e resultados da mineralização dos compostos foram estudadas. Neste estudo, foram escolhidos como modelo, três corantes monoazóicos com estrutura química semelhante: alaranjado de metila, vermelho de metila e amarelo de metila. Parâmetros operacionais como gap de descarga, potência aplicada, pH e temperatura do meio foram estudados na degradação dos corantes alaranjado de metila e vermelho de metila a fim de compreender a influência de cada parâmetro nas reações de degradação. Com base nesse estudo constatou-se, que a reação de degradação para ambos os corantes é favorecida quando a potência elétrica aplicada e a temperatura são aumentadas, mantendo constante o gap de descarga em 10 mm e em pH do meio ácido (2). Juntamente com o estudo da influência dos parâmetros operacionais foi realizado o estudo cinético das reações de degradação para os mesmos corantes. Para ambos, foi constatado que o perfil cinético da reação de degradação se ajusta ao modelo de ordem zero em relação aos corantes. Espécies químicas produzidas durante a reação de degradação como NO2-, NO3- e H2O2 foram identificadas no meio reacional. Através da cromatografia iônica, NO2- e NO3- foram quantificados em meio aquoso quando o plasma frio foi gerado em atmosfera de nitrogênio. Com base nisso, estima-se que o NO3- é possivelmente proveniente da oxidação do NO2- por H2O2. Estas espécies foram quantificadas e suas concentrações em fase aquosa são fortemente dependentes do tipo de gás de trabalho utilizado. Foi evidenciado que o chamado efeito pós descarga temporal, caracterizado pela degradação do corante em fase aquosa após aplicação do plasma, ocorre de acordo com um perfil cinético de pseudo primeira ordem; diferentemente da degradação direta pelo plasma. As espécies produzidas na degradação direta pelo plasma foram identificadas por espectrometria com ionização por eletronspray. Um possível esquema da reação de degradação foi proposto em função dos diferentes gases de trabalho utilizados na formação do plasma. Fica evidente a formação de espécies com peso molecular menor com o tempo de exposição ao plasma. A análise de carbono orgânico total indicou que quando o plasma é formado em atmosfera de argônio o percentual de remoção é maior. Em suma, o perfil cinético da reação de degradação para os corantes azo alaranjado de metila, vermelho de metila e amarelo de metila foi o mesmo e o processo caracterizado como ordem zero. / The present study describes the degradation process of three azo dyes in aqueous medium by corona discharge non thermal plasma. The influence of operating parameters on the working system, the degradation kinetic profile, the post-discharge effect, the identification of degradation byproducts, and the compounds mineralization results were studied. In this study, three monoazo dyes with similar chemical structure were chosen as a model: methyl orange, methyl red and methyl yellow. Operational parameters such as discharge gap, applied power, pH and temperature of the medium were studied on the degradation of the dyes methyl orange and methyl red in order to understand the influence of each parameter on the degradation reactions. Based on this study, it was found that the degradation reaction for both dyes is favored when the applied electric power and the temperature are increased, keeping a constant discharge gap of 10 mm and maintaining the acidic pH (2). Along with the study of the influence of operating parameters, a kinetic study of degradation reactions was performed for the same dyes. For both, it was found that the kinetic profile of the degradation reaction fits the model of zero order on the dye. Chemical species produced during the degradation reaction such as NO2-, NO3-and H2O2 were identified in the reaction medium. Through ion chromatography, NO2- and NO3- were measured in aqueous media when the non thermal plasma was generated in a nitrogen atmosphere. Based on that, it is estimated that the NO 3-is possibly coming from the oxidation of NO2- by H2O2. These species were quantified and their concentration in the aqueous phase are strongly dependent on the type of working gas used. It was evidenced that the called post-discharge temporal effect, characterized by the dye degradation in the aqueous phase after application of the plasma, takes place according to a pseudo first order kinetic profile, differently from direct degradation by plasma. The species produced by the plasma direct degradation were identified by ionization eletronspray spectrometry. A possible scheme of the degradation reaction was proposed according to the different working gases used to form the plasma. The formation of species with less molecular weight with the time of exposure to plasma became evident. The total organic carbon analysis indicated that when the plasma is formed in the argon atmosphere, the removal percentage is higher. In sum, the kinetic profile of the degradation reaction to the azo dyes methyl orange, methyl red and yellow methyl was the same and the process characterized as zero order.

Le but de cette thèse est d'améliorer les techniques d'analyse de données de la réflectométrie à balayage de fréquence pour la détermination du profil de densité des plasmas de fusion. Au cours des deux dernières décennies, des améliorations significatives ont été apportées sur la partie matérielle et sur d'extraction des signaux, mais l'analyse des données est en retard et nécessite d'autres améliorations pour répondre aux spécifications exigées pour un fonctionnement en continu des futurs réacteurs. Les améliorations obtenues lors de ce travail de thèse sur la reconstruction des profils de densité fournissent une meilleure précision en un temps plus court ceci même en présence de trou de densité conduisant à une mesure des propriétés de la turbulence suffisamment précise pour valider des modèles numériques et permettant la surveillance en temps réel de la forme et de la position du plasma / The goal of this PhD is to improve the data analysis techniques of frequency swept reflectometry for determination of the density profile of fusion plasmas. There has been significant improvements in the last two decades on the hardware design and signal extraction techniques, but the data analysis is lagging behind and require further improvements to meet the required standards for continuous operation in future reactors. The improvements obtained in this thesis on the reconstruction of density profiles provide a better accuracy in a shorter time, even in the presence of a density hole, also enabling sufficiently precise measurements of the properties of turbulence used to validate numerical models, and allowing real-time monitoring of the shape and position of the plasma

Made available in DSpace on 2015-09-17T15:26:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-08-03. Added 1 bitstream(s) on 2015-09-17T15:45:00Z : No. of bitstreams: 1 000847906.pdf: 2134043 bytes, checksum: d544b7fcf68a15d44f48104dd4595087 (MD5) / Este trabalho descreve o desenvolvimento de um dispositivo de geração de microdescargas de plasma operando à pressão atmosférica, sua caracterização e aplicação no tratamento de superfície polimérica. A microdescarga é produzida entre uma agulha e um eletrodo externo na forma de um cilindro. A agulha e o cilindro são dispostos coaxialmente com um capilar de borossilicato ou quartzo entre os mesmos. O sinal usado para excitar a descarga tinha a forma senoidal na frequência de 37 kHz. Estas microdescargas produziram plumas de plasma na extremidade da agulha. Medições da tensão de ruptura mostraram regimes distintos conforme a posição axial do cilindro em relação à agulha. Simulações com circuitos mostraram diferentes circuitos equivalentes ao dispositivo de microdescarga conforme esta posição relativa entre os eletrodos. Utilizando estas plumas no tratamento de superfícies de PET verificou-se redução do ângulo de contato com o tratamento que atinge um mínimo para tempos de 10 s. O ângulo de contato para diferentes posições em torno do ponto de tratamento foi ajustado à curvas baseadas em funções gaussiana e lorentziana. Isto possibilitou verificar o aumento da área tratada com o fluxo do gás quando a tensão na descarga se torna elevada. Para pluma de diâmetro menor que 1 mm o tratamento se estendeu em até 6 mm devido a dinâmica do gás da pluma. O dispositivo se mostrou confiável e com tratamento reprodutível na modificação das propriedades da superfície de materiais / This work describes the development and characterization of a microplasma jet device operating at atmospheric pressure and its application on the treatment of a polymeric surface. The micro discharge was produced between a needle and a coaxial cylindrical electrode with a borosilicate or quartz capillary between them. The discharge occurs in a small gap between the capillary and the needle and a plasma plume is produced at the tip of the needle. The signal used to excite the discharge was sinusoidal at frequency of 37 kHz. Breakdown voltage measurement showed distinct regimes according to the axial position of the cylinder relative to the needle. Simulations showed different equivalent circuits for the device according to the relative position between the electrodes. The plasma plumes were used to treat PET surfaces. It was observed the reduction of the contact angle with the treatment time that saturates around 10 s. The contact angle measurements at different positions around the treatment point were fitted using Gaussian and Lorentzian functions in order to estimate the diameter of treated circular area around the contact point of the plume with the surface. It was observed an increase of the treated area with the flow rate gas particularly at high applied voltage. Diameter up to 6 mm was achieved for plasma plumes with diameter smaller than 1 mm due to gas dynamic effects. The repeatability on the treatment showed that the plasma jet is reliable to modify surface properties of materials