Dissertations / Theses on the topic 'Plasma diagnostic techniques'

Dry etching processes are crucial to the fabrication of VLSI and ULSI circuits and are likely to continue so for the foreseeable future. However, the technique remains difficult to implement and is not well understood. To a great extent, this is a result of the use of novel machine configurations and chemical recipes which are employed far in advance of any real understanding of the interactions occurring within the process chamber. Historically, process development in this field has proceeded as a result of improvements in vacuum technology coupled to empirical one-dimensional trend analyses. These traditional approaches to process development have become severely limited with the advent of ULSI. This project addressed the requirement for improved process characterisation by investigating diagnostic techniques and rigorous statistical modelling as applied to one of the most challenging leading edge processes: the BCl<SUB>3</SUB>/Cl<SUB>2</SUB>/He dry etching of aluminium alloys. Optical emission spectroscopy, electrostatic Langmuir probes and mass spectrometry were used to investigate the dry etch behaviour. During this research, a novel in-situ SIMS implementation of the mass spectrometer was used to investigate plasma generated positive ions. Details of detected ions and intensities during etching are presented. A CCF experimental design was formulated from the major RIE machine parameters of rf power, system pressure and % Cl<SUB>2</SUB>/BCl<SUB>3</SUB>. The final quadratic model covered 3 manipulated machine variables, 3 process parameters and 6 performance parameters. This is the first time that rigorous statistical modelling techniques have been applied to the BCl<SUB>3</SUB>/Cl<SUB>2</SUB>He based process or to an aluminium dry etch process in order to systematically characterise both the process and performance behaviour. This work presents these models, along with an estimate of each model's accuracy.

In this work, the characteristics of plasma jets produced by a commercial DC plasma spray torch connected to a controlled pressure chamber are investigated. The plasma gas employed is a mixture of argon, nitrogen and hydrogen with the initial gas flow rates of 40, 10, and 1 SLPM respectively. The plasma torch is operated at chamber pressures of 6.5, 13, 26, 39, 53 and 101 kPa and a fixed input power of 17.5 kW. Optical emission spectroscopy is used to measure the temperatures and electron density profiles. The measurements of temperature are carried out by means of a Boltzmann plot of several isolated argon atom spectral lines. The electron density is measured from the Stark broadening of the H[subscript bêta] line 486.1 nm and the continuum emissivity. Partially resolved spectra of the N[subscript 2]+ molecular band are used for the rotational temperature evaluation. The rotational emission from the (0,0) band of the first negative system is compared to synthetic spectra to evaluate the rotational temperature within the flow field. Finally, the measurements of the gas kinetic temperature and the plasma velocity are performed by the enthalpy probe technique. The experimental results show the occurrence and the position of the different gas dynamics zones; i.e., supersonic expansion, stationary shock front and subsonic relaxation at low pressures (less than 40 kPa). The plasma flow is accelerated to its maximum velocity at the expansion where a minimum in the electron density and temperature is observed. At the end of the expansion a stationary shock front occurs at 4, 8, 12, and 15 mm downstream from the nozzle exit at pressures 39, 26, 13 and 6.5 kPa respectively. The electron density profiles show the variations along the plasma axis that coincide with the position of the shock waves. Good agreement between the electron density results obtained from the Stark broadening and from the continuum emissivity is observed. Enthalpy probe measurements on gas kinetic temperature and plasma velocity reveal the general features of low pressure plasma jets, i.e., higher flow velocity and longer heating zone of expanded plasma with lower temperature. The measurements also coincide with the rotational temperature obtained from emission spectroscopy. The temperature results confirm that the local thermodynamic equilibrium LTE exists at pressures of 100 and 53 kPa. However, at lower pressures where the supersonic shock waves are formed, the slow energy exchange between the heavy and light particles leads to significant deviations from the LTE especially in the shock region.

Le procédé de projection plasma à pression réduite (voire très réduite, inférieur à 10mbar) est en plein essors et connaît actuellement un développement considérable. Cette technique permet d’obtenir des revêtements très denses avec un taux de porosité très faible tout en gardant un bon rendement de projection. Les caractéristiques des dépôts sont directement liées aux paramètres de projection (gaz plasmagène, puissance de la torche, débit de poudre), le réglage de ces paramètres peut être fait en mesurant les caractéristiques du plasma et des particules en vol. Le développement d’un tel procédé nécessite donc des moyens de diagnostics et de contrôles performants. Le but de ce travail est d’explorer les différents moyens de diagnostic optique applicable dans de telles conditions de projection. Notre approche pour cette étude utilise principalement le DPV2000 et la spectrométrie d’émission. Le DPV2000 est utilisé pour les mesures de la température, la vitesse et le diamètre des particules en vol. Dans le cas de fines particules et/ou de basse température les particules sont éclairées par un laser afin de mesurer la vitesse et le flux de particules en vol. La spectrométrie d’émission pour l’étude de la vaporisation des particules en vol et les dimensions de l’écoulement plasma<br>There is an increasing interest for thermal plasma spraying at working pressure lower than 10 mbars. By spraying at such low pressure, it is expected that resulting coatings have a very low porosity while keeping a deposition rate higher. Developing such processes requires adjusting operating parameters as gas mixtures, arc current and particle injection quantities, among others, in correlation with coatings to produce. Setting input parameters of this new spray processes can be made by measuring characteristics of the plasma and sprayed particles by using optical diagnose techniques. The aim of this study is to develop the use of different tools for optical diagnostics under such conditions. Particle measurements are performed by using the system DPV2000 with its sensor head located in a cooled tube at atmospheric pressure and measuring the particles through an optical window. When particles are too small or too cold to be detected, they are illuminated by a laser diode. In that case particle temperature measurements are not possible anymore but it is still possible to measure the in-flight particle velocity and flux. In addition to particle diagnostics, optical emission spectroscopy is used to quantify the plasma volume and to study the sprayed particle vaporization. The results allowed defining the characteristics of future process chamber to perform thermal spray technique at 0,1mbar pressure

Les efforts entrepris pour améliorer les performances des moteurs aéronautiques (réduction du délai d’allumage, prévention de l’extinction de flammes, extension des limites de flammabilité, réduction des émissions polluantes…) nécessitent de nouveaux concepts de combustion impliquant notamment l’utilisation de systèmes d’injection de carburant liquide basés sur la technologie Lean-Premixed-Prevaporized (LPP). Cependant, ces systèmes d’injection peuvent produire des instabilités de combustion qui induisent des contraintes dommageables pour leur exploitation industrielle. Ces perturbations peuvent néanmoins être réduites par de nouveaux concepts technologiques visant à modifier la cinétique chimique de la combustion. Celle-ci se produit par une production significative d’électrons qui ont pour rôle de produire un plasma hors-équilibre responsable de la dissociation partielle des réactifs en radicaux. Les radicaux, ainsi créés, contribuent à un accroissement des mécanismes réactionnels pouvant même conduire à l’allumage du mélange fuel/air. A la frontière entre les plasmas et la combustion, l’objectif de cette thèse pluridisciplinaire est d’améliorer notre compréhension sur les mécanismes thermiques et chimiques d’oxydation des réactants ainsi que sur les possibilités d’allumage du combustible induits par une décharge électrique nanoseconde produite dans un mélange gazeux méthane/air à pression atmosphérique. Le plasma hors-équilibre est produit par des impulsions de tension de 15kV et de largeur à mi-hauteur de 20 ns, répétée à une cadence maximale de 300Hz. Les évolutions temporelles des distributions de concentration de OH, CH et de H2CO sont mesurées par imagerie de fluorescence induite par laser (PLIF). Les mesures sont réalisées pour différentes richesses autour des limites d’allumage (0,5 – 1,3) dans le but de souligner les processus chimiques produits par la décharge hors-équilibre et non par la combustion elle-même. Les résultats expérimentaux associés à des mesures de température par DRASC sur N2 (Diffusion Raman anti-Stokes Cohérente) et à des caractérisations des propriétés électriques (température des électrons et densité des électrons) par diffusion Thomson sont ensuite comparés avec des simulations numériques réalisées avec le logiciel CHEMKIN couplé au mécanisme réactionnel dédié à la combustion du méthane : GRI-Mech 3. 0. Les résultats de cette comparaison soulignent les principaux mécanismes réactionnels contrôlant l’allumage d’un mélange méthane/air. En particulier, une réduction conséquente du délai d’allumage observée expérimentalement est confirmée numériquement. La production significative de radicaux à partir de l’interaction plasma/fluide mène alors à un allumage en moins de 1 s. Ce délai est plus faible de plusieurs ordres de grandeur que celui observé avec un allumage conventionnel thermique. L’intégration de ce type d’actionneur plasma sur un injecteur LPP implique de connaître également le comportement des gouttes en présence du plasma. La dernière partie de ma thèse traite de cette interaction. Pour illustrer les effets thermomécaniques de la décharge sur une goutte isolée, une expérience est réalisée sur un jet de gouttes monodisperses auquel est combiné le système d’électrodes utilisée lors des expériences en milieu gazeux. La technique d’ombroscopie sert à caractériser cette interaction. Après passage des gouttes au travers de la décharge, ces dernières augmentent en taille pendant un délai de 30 μs puis se relaxent jusqu’à revenir à leurs conditions initiales. Des comportements similaires sont obtenus quelque soit le combustible (éthanol, eau, n-undecane et acétone). Des simulations numériques prenant en compte l’hypothèse du « flash boiling atomization » permettent de retrouver des évolutions similaires à l’expérience tout en donnant une interprétation à la nucléation au sein d’un fluide plongé dans un champ électrique à partir des données expérimentales<br>Efforts to further improve performances of aircraft jet engines (reduction of ignition delay, flame blow-off prevention and extension of flammability limits, reduction of pollutant emissions …) require new concepts of injection systems like for instance, Lean-Premixed-Prevaporized (LPP) injectors. However, these injection systems can produce combustion instabilities which induce serious limitations (i. E. Flashback) for industrial exploitation. We argue these perturbations can be mitigated by using alternative methods consisting on modifying the chemical kinetics of the combustion by generating and sustaining large electron number densities, which result in a non-equilibrium excitation of the gas mixture which favours the partial dissociation of reactants into radicals. These radicals then react releasing energy and broadening the radical pool and thereby ignite the fuel/air mixture. At the frontier between plasmas and combustion, the objective of this multidisciplinary thesis consists to improve our knowledge on the thermodynamics and kinetic mechanisms of fuel oxidation and also on the properties of ignition induced by a nanosecond pulsed discharge produced in an atmospheric methane/air mixture. The non-equilibrium plasma is produced by repetitive electrical pulses of 15 kV peak voltage, 20 ns pulse width and 300 Hz maximum repetition rate. Probing of the pulsed discharge has been performed with Laser-induced fluorescence (PLIF) in order to measure the temporal distributions of OH, CH and CH2O species concentrations during the plasma/gas mixture interaction. Measurements were performed for various equivalence ratios surrounding the ignition limits (0. 5 – 1. 3) in order to highlight the chemical processes produced by the discharge and not those induced by combustion. The experimental results combined with temperature CARS measurements (coherent anti-Stokes Raman scattering) and with electrical properties (electron temperature and electron density) obtained by Thomson scattering were compared with numerical simulations performed with the CHEMKIN program associated with the detailed chemical mechanism designed for the kinetic of methane/air mixtures: GRI-Mech 3. 0. The results of this comparison highlighted the main kinetic paths controlling the ignition of methane/air mixtures. In particular, a large reduction of ignition delay observed experimentally has been numerically confirmed. The production of enough radicals from the plasma/gas interaction leads to ignition in less than 1 s. This delay is several orders of magnitude lower than the conventional ignition delay times observed with thermal ignition. The integration of the plasma actuator within a LPP injector involves also the knowledge of the interaction between plasma and droplets. The last part of this thesis deals with this interaction. To highlight thermomechanical effects of the discharge on one single droplet, an experiment including a monodispersed droplet stream coupled with the electrodes configuration from the gaseous experiments was performed. Shadowgraphy was used to characterize this interaction. After passing through the plasma the droplet grows in size during a period of around 30 μs then collapses. Similar behaviours are obtained whatever the fuel composition of the droplet (ethyl alcohol, water, n-undecane and acetone). Numerical simulations have been used to study the nucleation of a liquid inside an electric field with regards to the experimental data. “Flash boiling atomization” assumption was then used to obtain the same orders of magnitude observed on the experimental data

Le propos de cette thèse concerne l'étude des caractéristiques métrologiques des composants des chaînes de cinématographie opérant dans le domaine picoseconde. Un accent particulier est porté sur les propriétés de planétisme de la caméra à balayage de fente. Le document rapporte les méthodes expérimentales mises en œuvre pour accéder aux différentes grandeurs métrologiques. Elles utilisent de manière intensive l'instrumentation automatisée et les techniques d'approximation pour l'extraction de l'information, ce qui favorise le traitement d'un important volume de mesures. Les données recueillies sont mises à profit pour la correction des défauts inhérents à certains composants au travers de méthodes de traitement d'images (restauration). Les résultats montrent un gain substantiel en performances qui rend très attractive cette approche au regard des difficultés liées à l'amélioration technologique des éléments de la chaîne de cinématographie<br>The thesis purpose is dedicated to the study of the metrological characteristics of picosecond range high speed photography chain components. A special focus is turned to the streak camera planatism properties. The document reports experimental methods implemented to evaluate several metrological quantities. They intensively use automated instrumentation and mathematical approximation techniques to extract information, so that a large amount of measurements can be easily processed. Collected data are turned to account to correct defects due to some components through image processing methods (restoration). Results exhibit a gain in performance which makes this approach very attractive when looking at the difficulties encountered with technical improvements of high speed photography chain sub-systems

Lysophosphatidic acid (LPA) influences many physiological processes, such as brain and vascular development. It is associated with several diseases including ovarian cancer, breast cancer, prostate cancer, colorectal cancer, hepatocellular carcinoma, multiple myeloma atherosclerotic diseases, cardiovascular diseases, pulmonary inflammatory diseases and renal diseases. LPA plasma and serum levels have been reported to be important values in diagnosing ovarian cancer and other diseases. However, the extraction and quantification of LPA in plasma are very challenging because of the low physiological concentration and similar structures of LPA to other phospholipids. Many previous studies have not described the separation of LPA from other phospholipids, which may make analyses more challenging than necessary. We developed an SPE extraction method for plasma LPA that can extract LPA at high purity. We also developed an HPLC post-column fluorescence detection method that allows the efficient quantification of LPA. These methods were used in a clinical study for ovarian cancer diagnosis to help validate LPA as a biomarker of ovarian cancer. Moreover, molecular imprinted polymers (MIPs) were designed and synthesized as material for the improved extraction of LPA. Compared to the commercially available materials, the MIP developed shows enhanced selectivity for LPA. The extraction was overall relatively more efficient and less labor-intensive.

Dans son ensemble, les techniques de pointe actuelles procurent l'information nécessaire à une analyse approfondie de la cellule, ce qui nécessite cependant l’utilisation d’instruments et de plateformes analytiques différentes. Les biopuces à cellule permettent l’analyse des cellules vivantes en temps réel et constituent donc un outil important pour de nombreuses applications dans la recherche biomédicale telles que la toxicologie et la pharmaceutique.En effet, le suivi en temps réel de la réponse non-seulement physique mais aussi chimique des cellules, obtenue suite à des stimuli externes spécifiques et en utilisant un système d'imagerie cellulaire, peut fournir une meilleure compréhension des mécanismes et des voies de signalisation impliquées dans la réaction toxicologique.Le développement de tels dispositifs multianalytiques pour l'analyse biologique repose essentiellement sur la capacité de produire des surfaces fonctionnelles de pointe permettant une interaction et organisation contrôlée des cellules et d'autres entités telles que par exemple des anticorps ou des nanoparticules. Par conséquent, un grand effort technologique repose sur le développement des techniques permettant la création de motifs fonctionnels sur une surface de nature souvent inerte. Dans cette thèse, nous proposons deux techniques de micro- et nanofabrication permettant la création de motifs de cellules et d’anticorps sur un revêtement non-adhésif composé de poly (oxyde d'éthylène) (« PEO-like ») déposé par plasma. La première approche consiste à immobiliser par physisorption un micro-réseau de molécules adhésives de la matrice extracellulaire (par exemple la fibronectine) en utilisant des techniques d’impression par microcontact et par non-contact. La deuxième approche permet la création de motifs adhésifs sur la surface constitués de nanoparticules d'or (Au NPs) en utilisant des techniques d’impression similaire. L'immobilisation des Au NPs sur le revêtement « PEO-like » ne nécessite pas de modifications chimiques et est réalisé par une technique d'autoassemblage simple et irréversible. Ces surfaces d'or nanostructurées ont été testées pour l’analyse du phénomène de reconnaissance biomoléculaire et en tant que plateforme de culture cellulaire. Finalement, cette plateforme a été intégrée à un microscope plasmonique qui a permis, de façon préliminaire, la surveillance et la visualisation de la motilité d’une cellule unique, cela en temps réel et sans marquage, ainsi que la détection spécifique et sensible de protéines tests<br>State of the art techniques give as a whole the required information needed for the complete cell analysis but require different instruments and different types of platforms. The concept of cells on-a-chip allowing real-time analysis of living cells is, therefore, an important tool for many biomedical research applications such as toxicology and drug discovery. Monitoring in real-time the physical but also chemical response of live cells to specific external stimuli using live-cell imaging can provide a better understanding of the mechanisms and pathways involved in the toxicological reaction. The development of such multianalytical devices for biological analysis relies essentially on the ability to design advanced functional surfaces enabling a controlled interaction and organisation of cells and other nanostructures (e.g antibodies and nanoparticles). Therefore, a large technological effort is related on the development of advanced patterning techniques. In this thesis, we propose two simple and direct micro- and nano-fabrication techniques enabling the creation of cellular and sensing patterns on a non-adhesive and cell repellent plasma-deposited poly (ethyleneoxide) (PEO-like) coating. The first approach consists in immobilising a microarray of ECM molecules (cell-adhesive proteins, e.g fibronectin) on the cell repellent PEO-like surface by physisorption using microspotting or microcontact printing techniques. The second approach enables the creation of Gold nanoparticles (Au NPs) adhesive patterns on the surface using similar spotting techniques. The immobilization of Au NPs on PEO-like coatings does not require any prior chemical modifications and is achieved by a straightforward and irreversible self-assembly technique. These gold nanostructured surfaces have been tested for protein bio-recognition analysis and as a cell culture platform. Ultimately, this platform was integrated to a novel plasmonic microscope which enabled, preliminarily, the label-free monitoring and visualisation of a single cell attachment and detachment in real time, as well as the specific and sensitive detection of test proteins in a cell-free environment

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

This thesis reports several advances in x-ray crystal spectroscopic techniques for the diagnosis of high-temperature magnetically confined plasmas. Two complementary spectrometers have been developed, and have been demonstrated in a wide range of experiments on the Culham Laboratory DITE and COMPASS tokamaks, and on the Joint European JET tokamak. A Bragg rotor' spectrometer uses a combination of crystals and multilayers to give complete coverage of the spectrum between 1 A and 100 A. Developments were made to extend the coverage from 25 A to 100 A, using multilayer mirrors and organic crystals. The success of the instrument depends largely on the development of a high-rate ( 107 count/s) gas proportional counter system, capable of covering the energy range from 100 eV to 10 keV. A Johann spectrometer uses a novel four-pillar jig to bend' crystals to typically 1 m radius. A large-area cooled x-ray CCD array is used in the focus, resulting in a compact high-resolution instrument. This allows line profile and ratio measurements with a time resolution of ~1 ms. Observations using the Bragg rotor spectrometer include impurity monitoring under various plasma and limiter configurations. Temperature and density sensitive line ratios were measured under known plasma conditions and compared with theory, adding confidence to their use for less well diagnosed plasmas such as those observed in astrophysics. A major application has been the study of a switch (controlled by the refuelling rate) between long and short impurity confinement times in the DITE tokamak. Trace impurities were injected by laser ablation, and their subsequent temporal and spatial behavour studied spectroscopically. Weak lines, due to radiative recombination into excited states of H- and He-like ions, were observed in the outer plasma. The radial profiles of these "radiative recombination lines" were governed by a balance between transport and, recombination, and allowed the effective diffusion coefficient to be measured locally. It was shown that the transport changes occurred in the outer half of the plasma, and that conditions in the core were unchanged. The suitability of Bragg spectroscopy for a reactor-relevant plasma was demonstrated during the JET preliminary tritium experiment (PTE). A double- reflection instrument was used, with a tritium-compatible radiation-shielded beamline. Based on this operational experience, a soft x-ray spectroscopy system for a next-step device such as ITER is proposed.

Le travail presente dans ce memoire concerne l'etude d'un plasma de depot et l'analyse des films organosilicies deposes dans une decharge basse frequence (2,5 khz). Une partie de l'etude de la phase gazeuse du plasma a porte sur la determination de la temperature electronique (te) et la densite electronique (n#e) et leur evolution en fonction des conditions de decharge (courant de decharge, pression). Il a demontre par la methode de la sonde de langmuir que n#e varie entre 10#7 et 10#8 cm##3, tandis que te2,0 ev est peu sensible aux conditions de decharge. Le diagnostic de la phase gazeuse par spectroscopie d'emission optique a mis en evidence la disymetrie de la decharge. L'emploi d'une fibre optique a permis de recueillir l'intensite d'emission des especes excitees a differentes hauteurs de l'espace interelectrode. Le maximum d'emission situe dans la region cathodique de la plupart des especes excitees montre une forte dissociation de la molecule du monomere dans cette region, ce qui conduit a un taux de croissance du film depose quatre fois plus eleve sur la cathode que sur l'anode. L'analyse des films deposes montre que les conditions de decharge n'influent pas beaucoup sur la structure des films. En revanche, des quantites de plus en plus importantes contribuent a l'elimination de la partie organique dans les films. Ces films minces sont utilises dans le domaine de la passivation des surfaces de semiconducteurs ou comme couches planarisantes

Neutron are emitted from a deuterium plasma with energies around 2.5 MeV. The neutron spectrum is intimately related to the ion velocity distribution of the plasma. As a consequence, the analysis of neutron energy spectra can give information of the plasma rotation, the ion temperature, heating efficiency and fusion power. The upgraded magnetic proton recoil spectrometer (MPRu), based on the thin-foil technique, is installed at the tokamak JET. The upgrade of the spectrometer was done to allow for measurements of deuterium plasmas. This thesis describes the hardware, the data reduction scheme and the kind of fusion plasma parameters that can be estimated from the data of the MPRu. The MPRu data from 3rd harmonic ion cyclotron resonance and beam heating are studied. Other neutron spectrometer techniques are reviewed as well, in particular in the aspect of suitability for neutron emission spectrometry at ITER. Each spectrometer technique is evaluated using synthetic data which is obtained from standard scenarios of ITER. From this evaluation, we conclude that the thin-foil technique is the best technique to measure, e.g., the ion temperature in terms of time resolution.

Le carbone présente de nombreuses formes allotropiques, dont le graphite, qui possède une large variété de formes géométriques d'intérêt pour l'industrie. Ce travail de thèse a permis la synthèse d'une nouvelle de ces formes: les pyramides hexagonales. Ces cristaux submicroniques sont créés à partir de substrats de graphite par gravure en plasma radiofréquence (rf) Ar/H2 basse pression. Pour comprendre la formation de ces nouveaux cristaux, la caractérisation des plasmas a été effectuée par sondes de Langmuir et absorption résonante laser afin de vérifier la température de surface et d'estimer les flux et énergies des ions. L'évolution temporelle de la gravure a été directement observée en microscopie électronique à balayage (MEB). La gravure chimique (Ar/H2) a formé des cônes de graphite à hélices dont les paramètres cristallins et une amorphisation de surface, due à l'hydrogène, ont été révélés par microscopie électronique en transmission (MET). La vitesse de gravure et l'état de surface montrent, en fonction du mélange, une zone de transition caractérisée par l'absence de structures. La gravure physique (Ar pur) conduit à la création des pyramides hexagonales de graphite. Un modèle de formation de ces cristaux a pu être proposé grâce à une bonne connaissance des différentes conditions plasma et des études poussées de microscopies électroniques sur plusieurs types de substrats. Les analyses MET haute résolution ont montré des boucles fermant les plans de bord du cristal et liées à sa formation. Nous avons également maîtrisé l'état de surface des substrats de graphite hautement orienté (HOPG) en créant une densité homogène de pyramides dont la taille peut être contrôlée<br>Carbon occurs as many different allotropic forms. One in particular, graphite, exhibits a remarkable variety of geometrical configurations largely used in industrial applications. This work permitted the synthesis of a novel crystalline form: the hexagonal-pyramidal graphite hillocks. These submicronic structures are created from graphite substrates by low pressure Ar/H2 radiofrequency (rf) plasma etching. In order to understand the formation of these new crystals, plasma characterization has been carried out by Langmuir probes and laser absorption spectroscopy to check the surface temperature and estimate the ion fluxes and energies. Etching kinetics has been directly observed by scanning electron microscopy (SEM). Chemical etching processes in pure hydrogen resulted in the creation of helical graphite cones whose crystal parameters and surface amorphisation have been revealed by transmission electron microscopy (TEM). The etching rate and surface topography as function of the gas mixture show a transition where no structures are created. The physical etching in pure argon creates hexagonal-pyramidal graphite hillocks. A formation model of these crystals has been proposed owing to a good knowledge of the different plasma conditions and thorough electron microscopy studies on two kinds of substrates. High resolution MET analyses showed graphene loops closing the edges planes along the crystal facets and related to the structure’s formation. We also showed the texturing of the surface of highly ordered graphite (HOPG) by creating a high and homogeneous density of crystals whose size may be controlled

INTRODUÇÃO: A determinação do genótipo RHD fetal no plasma materno é um teste de diagnóstico pré-natal não invasivo oferecido a gestantes RhD negativo que apresentam potencial de sensibilização e/ou Doença Hemolítica Perinatal. Atualmente, este exame é realizado de rotina em diversos países, mas não no Brasil. A Clínica Obstétrica do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (HCFMUSP) oferece atendimento terciário a gestantes RhD negativo, com monitorização dos títulos de anticorpos irregulares, administração da imunoglobulina anti-D e/ou terapêutica fetal, quando necessários. OBJETIVO: Avaliar a acurácia do teste semiautomatizado para determinação do genótipo RHD fetal no plasma materno. METODOLOGIA: Foram coletadas prospectivamente amostras de sangue de 220 gestantes RhD negativo, com idade gestacional entre 8-28 semanas. O plasma foi obtido em no máximo 2 horas após a coleta, e uma alíquota de 1 mL foi submetida à extração de ácidos nucléicos no equipamento automatizado MagNA Pure Compact (Roche), empregando o kit Large Volume. O DNA extraído foi submetido a PCR em tempo real (Step One Plus - Applied Biosystems), usando o protocolo do grupo SAFE, que tem como alvos os éxons 5 e 7 do gene RHD. RESULTADOS: Ocorreu exclusão de 35 amostras devido a problemas pré-analíticos, aborto ou desconhecimento do fenótipo do recém-nascido. Entre as 185 amostras analisadas, 130 (70,2%) foram genotipadas como RHD+ e 55 (29,8%) RHD-. Os resultados obtidos foram comparados com a fenotipagem do cordão umbilical, e houve concordância completa (100%). Sete amostras exibiram amplificação exclusiva para o éxon 7. Essas amostras foram submetidas aos protocolos em PCR convencional, e PCR em tempo real específico para o pseudogene RHD. Ambos os ensaios apresentaram os mesmos resultados: cinco positivos e dois negativos. Nesses mesmos 7 casos, após extração da camada de leucócitos materna, os protocolos foram repetidos, e o resultado confirmou que cinco mães eram RHD. As duas amostras com resultado negativo foram submetidas ao protocolo Multiplex, envolvendo os éxons 3-9 do gene RHD, com resultados negativos, confirmando que as mães são verdadeiramente RHD- portanto o sinal do éxon 7 é provindo dos fetos que são D variantes. CONCLUSÃO: O método para a determinação do RHD fetal no plasma materno descrito demonstrou ser rápido, de fácil execução, alta precisão e reprodutível, além de indicar possíveis variantes RHD em nossa população<br>BACKGROUND: Fetal RHD genotype determination in maternal plasma is a noninvasive prenatal diagnostic test performed in RhD negative pregnant women at risk of alloimmunization and/or Hemolytic Disease of Fetus and Newborn. Currently, this test is routinely performed in many countries but not in Brazil. The Department of Obstetrics at Hospital das Clínicas, São Paulo University Medical School provides tertiary antenatal care for RhD negative pregnant women including anti-D immunoglobulin administration, antibody levels monitoring and intrauterine treatment if necessary. AIMS: To validate the accuracy of a semi-automated test for fetal RHD genotype determination in maternal plasma. METHODS: Two-hundred and twenty blood samples were prospectively collected between 8 and 28 weeks of gestational age. Plasma processing was performed within 2 hours after blood collection, and nucleic acids were extracted from 1mL aliquots with an automated extraction platform (MagNA Pure Compact Roche) and the Large Volume kit. RHD gene exons 5 and 7 were amplified with real-time PCR (Step One Plus - Applied Biosystems) using the SAFE group protocol. RESULTS: Thirty-five samples were excluded due to pre-analytical problems, miscarriage and missing follow-up. In the remaining 185 samples, 130 (70.2%) were genotyped as RhD+ and 55 (29.8%) RhD-. Comparison with umbilical cord blood group phenotype showed 100% concordance. Seven samples showed amplification for exon 7 only. These were further investigated with conventional and real-time PCR with an specific protocol for RHD? pseudogene: 5 were positive and 2, negative. In these 7 cases, maternal buffy-coat DNA analysis also confirmed that 5 women were RHD?. In the remaining 2 cases, a multiplex protocol directed at RHD gene exons 3-9 confirmed that both mothers were truly RhD negative so exon 7 signal comes from the fetuses, further found to harbor D variants. CONCLUSION: The present study demonstrates that fetal RHD determination in maternal plasma is a fast, easy-to-perform and reproducible technique with high accuracy in our population. Moreover, it helps in the identification of possible RHD variants in our population

Les cyanobactéries sont des micro-organismes qui préoccupent les autorités de santé publique dans le monde entier, en raison de la toxicité des cyanotoxines qu'elles produisent. Certaines cyanotoxines dont les microcystines (MC) sont des hépatotoxines inhibitrices de protéines phosphatases à sérine/thréonine. Aujourd'hui, plus de 200 variants de MCs ont été identifiés. Il s'agit d'heptapeptides monocycliques synthétisés par voie non-ribosomale dont la MC-LR (cyclo- (D-Ala-L-Leu-D-érythro-β-méthylAsp-L-Arg-ADDA-D-Glu-N-méthyl-hydro-Ala) est le variant le plus étudié en raison de sa fréquence et de sa forte toxicité. L’objectif de cette étude est le développement d'une méthode d'immunoanalyse rapide, sensible et fiable pour détecter les MCs. Le projet vise donc à développer un outil alternatif de détection de la MC-LR, qui serait mieux adapté aux analyses sur le terrain que les méthodes analytiques, biologiques ou les méthodes d'inhibition d'activité enzymatique actuellement disponibles. L'originalité de ce projet réside dans l'utilisation de deux approches différentes pour sélectionner de nouveaux anticorps spécifiques de la MC-LR. La première repose sur l'immunisation d'animaux de laboratoire, la technologie d'hybridation cellulaire et la sélection d'hybridomes sécréteurs d'anticorps monoclonaux. Si la méthodologie mise en œuvre a effectivement permis d'obtenir des immun-sérums spécifiques, la sélection des hybridomes d'intérêt reste à optimiser. La seconde stratégie mise en œuvre est basée sur la technologie du phage display pour sélectionner des fragments d'anticorps spécifiques de MC-LR à partir d'une banque de taille d’environ 109 phages, exprimant en surface des anticorps sous un format scFv (Shahsavarian et al., 2014). Plusieurs méthodes de criblage ont été développées et trois scFv ont été sélectionnés et étudiés, parallèlement à un quatrième scFv identifié dans une étude précédente (McElhiney et al., 2002), tous spécifiques à la MC-LR. Ces scFv ont été produits sous forme libre, soluble et leur spécificité à la MC-LR a été évaluée par ELISA et résonance plasmonique de surface. Les résultats obtenus montrent que les scFv sélectionnés sont tous capables de reconnaître la MC-LR. Néanmoins, ces résultats sont peu reproductibles et remettent en question le protocole de renaturation utilisé. Un travail de fond sur l’optimisation du protocole de renaturation s’avèrerait nécessaire pour les scFv ici sélectionnés, afin d’identifier les paramètres précis aboutissant à la perte ou au gain de leur fonctionnalité<br>Cyanobacteria are ubiquitous microorganisms that present a worldwide concern to public health authorities because of the toxicity of the cyanotoxins they produce. Some cyanotoxins are hepatotoxins such as microcystins (MCs). At least 200 variants of MCs have been identified till today. In our study, we focus on MC-LR, a monocyclic heptapeptide (cyclo-(D-Ala-L-Leu-D-erythro-β-methylAsp-L-Arg-ADDA-D-Glu-N-methyldehydro-Ala), since it is the most frequently detected and one of the most toxic. In our study, we are interested in developing a fast, sensitive and reliable method to detect MCs. The project aims to develop an alternative pollution detection method that would be better suited to field measurements than the physicochemical methods currently available. The originality of this project lies in the use of two different approaches to select a panel of antibodies suitable for the development of immunodetection tests. The first one is based on the hybridoma technology for the production of monoclonal antibodies. The second one is based on phage display technique to select antibody fragments that are specific to MC-LR from a library of approximately 109 phages, expressing on the surface scFv fragments (Shahsavarian et al., 2014). Two monoclonal antibodies were selected using the first approach, and their specificity was evaluated using ELISA technique. Along with three scFvs selected from phage display approach. An additional scFv was added to this list: 3A8, selected from a previous study (McElhiney et al., 2002) and also specific to MC-LR. The scFvs were cloned into an expression vector in order to get each clone in its scFv soluble form. Then, their specificity to MC-LR was evaluated using ELISA technique and Surface plasmon resonance. The results show a potential specificity to MC-LR. Nevertheless, these results are not very reproducible and call into question the refolding protocol used. A thorough work on this protocol optimization would be necessary, in order to find the key parameters that control the loss or gain of their functionality

Three novel diagnostic techniques were developed for plasma-enhanced chemical vapor deposition (PECVD), an important step in integrated-circuit manufacture. Results are presented for the deposition of amorphous hydrocarbon films from methane-argon plasmas. The plasma was formed between the powered and grounded electrodes of a 13.56-MHz parallel-plate reactor. A 5-to-1 mixture of methane/argon was fed to the reactor at 15, 30, 60, or 90 sccm. Pressure was held at either 0.1 or 0.5 torr, while rf power was set at 25, 50, 75, or 100 W. The three diagnostic techniques used were molecular-beam mass spectrometry, microprobe mass spectrometry, and Langmuir probing. Molecular-beam mass spectrometry was used to measure stable and radical species concentrations at a fixed point on the grounded electrode. Mole-fraction measurements were made for nine stable (CH$\sb4$, H$\sb2$, $\rm C\sb2H\sb2$, $\rm C\sb2H\sb4$, $\rm C\sb2H\sb6$, $\rm C\sb3H\sb4$, $\rm C\sb3H\sb6$, $\rm C\sb3H\sb8$, and Ar) and three radical species (H, CH$\sb2$, and CH$\sb3$); upper-bound estimates were made for five additional radical species (CH, C$\sb2$H, $\rm C\sb2H\sb3$, $\rm C\sb2H\sb5$, $\rm C\sb3H\sb3$). By applying microprobe mass spectrometry, distinctive in the study of plasma chemistry, detailed one- and two-dimensional spatial profiles of stable species (CH$\sb4$, H$\sb2$, $\rm C\sb2H\sb2$, $\rm C\sb2H\sb4$, $\rm C\sb2H\sb6,$ and Ar) were measured. Particular interest was focused on the entrance region. Langmuir probing was used to determine one-dimensional profiles of electron-energy distribution functions (eedfs). From the measured eedfs, electron densities and average electron energies were determined; furthermore, dissociation rate constants were calculated by integrating the product of the eedf and the dissociation cross section. Rate and rate-constant information were analyzed and correlated. By applying a transport analysis to the axial-centerline microprobe data, spatial rates of convection, diffusion, and reaction were determined. By using electron-density and electron energy profiles along with the reaction-rate profiles, energy-dependent rate constants were determined. A CSTR analysis was applied to bulk-plasma measurements to determine rate coefficients, and the results were compared to the transport-analyzed rate constants. Using a 2$\sp3$ factorially designed experiment, the effect of operating conditions (pressure, rf power, and flowrate) on the plasma chemistry and the deposition rate was explored.

The present thesis is the result of a research period at the Institute of Space and Astronautical Science of the Japanese Aerospace Exploration Agency, ISAS/JAXA within Funaki Laboratory of the Department of Space Flight Systems that followed the path of plume plasma diagnostics for space electric propulsion drives. During the experimental studies two high-current hollow cathodes and an innovative prototype of a low-voltage fully external discharge plasma thruster (XPT) had their plasma plumes diagnosed using electrostatic probes and retarding potential analyser (RPA). A Hall thruster and hollow cathode plume is defined as an unmagnetised quasi-neutral plasma which is mainly formed of neutral particles, electrons, singly and doubly charged ions. Plasma diagnostic techniques provide information through practical observations in order to fully understand the dynamics of the aforementioned plume components, the physical processes taking place within the plume and their effects on the spacecraft, for instance. Mastering these aspects of the plasma plume of space electric propulsion drives bolster the design processes, leading to highly efficient devices. Firstly, the introduction provides insights on the fundamental principles of hollow cathodes and Hall thrusters and a brief presentation of the plasma diagnostic techniques used during the research: single and double Langmuir probes, emissive probes and retarding potential analyser. Then, the fundamental plume diagnostics principles are depicted in an exhaustive way, departing from classical plasma kinetic theory, energy distribution functions and ending with an overview on the theory of charge collection by cylindrical probes. Subsequently, peculiarities of various analysis techniques are exposed for the Langmuir probes, emissive probes and RPA, with an emphasis on their strengths and demerits. The experimental setups for the cathodes and XPT plume diagnostic procedures are then outlined. The experimental logic, setup and electrical diagrams as well as a presentation of each probe design and manufacturing details are extensively discussed. The hollow cathodes experimental results are exposed with a discourse that aims of overviewing the difference between the various data analysis methods applied for the raw data. A discussion ensued based on the results in order to effectively identify mechanisms that produced the observed plasma parameters distributions. For the first time, the plume of a fully external discharge plasma thruster was diagnosed utilising double Langmuir probes.  The thesis highlights the main results obtained for the XPT far-field plume plasma diagnostics. The experimental findings for both thruster centreline positions and 2D plume maps for several axial distances away from the anode plate offer a ground basis for future measurements, a comparison term and a database to support ongoing computational codes. The results are discussed and related to the thruster performances data obtained during previous experiments. The thesis includes consistency analyses between the experimental data and the numerical simulation results and the uncertainties in measured plasma parameters associated with each data analysis procedure are evaluated for each data set. Last, the conclusions underline the main aspects of the research and further work on the previously mentioned plasma diagnostic techniques for hollow cathodes and XPT is suggested.<br>La présente thèse est le résultat d'une période de recherche à l'Institut des Sciences Spatiales et Astronautiques de l'Agence Spatiale Japonaise, ISAS / JAXA qui a suivi la voie des diagnostics du plasma de la plume de propulseurs électriques spatiaux. Au cours des études expérimentales, deux cathodes creuses à fort courant et un prototype innovant d'un propulseur basse tension à décharge externe de plasma (XPT) avaient leurs faisceaux de plasma diagnostiqués en utilisant des sondes électrostatiques et un analyseur à potentiel retardé. La plume d’un propulseur à effet Hall et d’une cathode creuse est définie comme un plasma quasi-neutre non-magnétisé qui est principalement formé de particules neutres, d’électrons, d’ions monovalents et bivalents. Les techniques de diagnostic du plasma fournissent des informations, via des observations pratiques, afin de bien comprendre la dynamique des composants de la plume mentionnés ci-dessus, les processus physiques qui se déroulent dans la plume et leurs effets sur une sonde spatiale, par exemple. La maîtrise de ces aspects du plasma de la plume généré par les propulseurs électriques spatiaux renforce les processus de conception de ce type de propulsion, ce qui conduit à des dispositifs hautement efficaces. Tout d'abord, l'introduction donne un aperçu sur les principes fondamentaux de cathodes creuses et de propulseurs à effet Hall, et une brève présentation des techniques de diagnostic du plasma utilisées lors de la recherche : sondes de Langmuir simples et doubles, des sondes émissives et d’analyseur à potentiel retardé. Ensuite, les principes fondamentaux de diagnostic de la plume sont représentés de manière exhaustive, d’abord la théorie cinétique classique du plasma, les fonctions de distribution en énergie et pour terminer une vue d'ensemble de la théorie de la collecte de charge par des sondes cylindriques. Par la suite, les particularités des diverses techniques d'analyse sont exposées pour les sondes de Langmuir, les sondes émissives et RPA, en mettant l'accent sur leurs avantages et leurs inconvénients. Les montages expérimentaux pour les procédures de diagnostic de la plume-plasma de cathodes et du XPT sont ensuite décrits. La logique expérimentale, les schémas électriques ainsi qu'une présentation de la conception et de la fabrication de chaque sonde sont largement discutés. Les résultats expérimentaux pour les cathodes creuses sont exposés de façon à présenter la différence entre plusieurs méthodes d'analyse de données appliquées aux données brutes. Une discussion s’ensuit, basée sur les résultats afin d'identifier efficacement les mécanismes qui ont produits les propriétés électroniques observées. Pour la première fois, la plume d'un propulseur à décharge externe de plasma a été diagnostiquée en utilisant des sondes de Langmuir doubles. La thèse met en évidence les principaux résultats obtenus pour le diagnostic en champ lointain de la plume-plasma du XPT. Les résultats expérimentaux pour les positions sur l'axe du propulseur et le cartes 2D de la plume pour plusieurs distances axiales loin de l’anode offrent une base pour de futures mesures, un terme de comparaison et une base de données pour appuyer les codes numériques. Les résultats sont discutés et sont rapportés aux données de performances du propulseur obtenus lors des essais précédents. La thèse comprend des analyses de la cohérence entre les données expérimentales et les résultats de simulation numérique, et les incertitudes des paramètres mesurés du plasma associées à chaque procédure d'analyse des données sont évaluées pour chaque ensemble de données. Enfin, les conclusions soulignent les principaux aspects de la recherche et une poursuite des travaux sur les techniques de diagnostic de plasma pour les cathodes creuses et le XPT est suggérée.

Sustainable and low emission combustion requires new combustion paradigms and solutions to increase efficiency, comply with more stringent regulations on pollutants, and cope with the varying qualities of renewable fuels. Plasma Assisted Combustion (PAC) could be one of the tools to achieve these goals in practical combustion systems. Previous studies showed that PAC can be used in a variety of applications: to improve ignition in difficult environments, to extend the operating range of burners to leaner conditions, to contrast thermoacoustic instability, to allow flame-holding in extreme conditions, and more. While applications keep being proposed, there are efforts to model and understand the coupling between flames and plasma discharges. This work contributes to the unraveling of the action of plasma discharges on flames by performing a number of investigations on a simple PAC burner. Trends and temporal evolution of key chemical species and electric fields are measured during plasma actuation of the flame. Experimental datasets resulting from this work are meant to be used in cross-validating numerical simulations. The considered PAC burner generates a lean methane-air stagnation flame, across which discharges are applied, developing partially in the fresh and partially in the burned gases. Time-resolved 2D imaging of atomic hydrogen and oxygen is obtained by using two-photon absorption planar laser induced fluorescence (TALIF) while OH and CH radicals are measured by using planar laser induced fluorescence (PLIF). To measure the electric field, the Electric Field Induced Second Harmonic generation (EFISH) technique is used. A novel deconvolution-like post-processing procedure is proposed and used to calibrate the measurements and improve the spatial resolution, overcoming limitations and distortions typical of EFISH measurements. Presented results quantify the effect of the plasma actuation on the flame and lend themselves to the validation of numerical models.