Les alliages légers (Al, Mg) sont aujourd’hui majoritairement utilisés dans les industries aéronautique, électronique, automobile. Toutefois, la faible résistance à la corrosion et à l’abrasion de ces alliages restreint leur développement à grande échelle. Les nouveaux concepts de protection contre la corrosion des alliages légers se basent non seulement sur un effet barrière par une couche épaisse d'oxyde (PEO) ou peindre, mais surtout sur une protection active à l’aide d’inhibiteurs de corrosion spécifiques. Ces inhibiteurs de corrosion pourraient être libérés "sur demande" et génèrent un phénomène ‘d’auto guérison’. L’utilisation des méthodes d’analyse in situ and ex situ modernes spectroscopiques pourraient permettre de mettre en lumière l’évolution de systèmes aussi complexe et aider à mieux définir les facteurs régulant ces processus. / Nowadays light alloys (Al, Mg) are widely used in a number of areas such as electronics, aeronautic, automotive and construction industries. However, the low corrosion and wear resistance of these alloys hinders application of Al and Mg alloys on a larger scale. The new concepts for corrosion protection of light alloys should include not only barrier protection by a thick oxide layer (PEO) or by paint but also an active protection by specific corrosion inhibitors which can be released “on request” and ensure so-called “self-healing”. Use of in situ and ex situ spectroscopic methods could bring a new view to the evolution of such a complicated system and help to define factors controlling these processes.

<p>A specific class of small-scale plasmas (column diameters in a sub-mm to mm range) at rarefied pressures (under 10 Torr) enclosed in glass tubes hold significant interest currently in the scope  of  tunable  plasma  devices.  Specifically,  applications  of  these  plasmas  include  plasma antennas and plasma photonic crystals. Reliable diagnostics are necessary for the development and implementation of these technologies as conventional tools are inadequate in such small-scale plasmas.</p> <p>Coherent microwave scattering in the Thomson regime (TMS) was recently demonstrated for diagnostics of electron number density in miniature free-standing laser-induced plasmas in air under  10  Torr  with  plasma  column  diameters  <  0.5  mm.  However,  measurements  by  TMS diagnostics have never been applied for small-scale plasma objects enclosed within glass tubes. Additionally, TMS measurements were never independently confirmed with a previously verified experimental technique. This work aims to validate results of TMS measurements for small-scale plasma  objects  enclosed  within  glass  tubes  using  the  previously  established  and  well-known hairpin resonator probe. A DC discharge plasma column of fairly large diameter (about 1.5 cm) is used in the experiments to ensure reliable non-intrusive measurements by the hairpin resonator probe.</p> <p>The experiments were conducted in a DC discharge tube with a diameter of 1.5 cm and a length of 7 cm. TMS diagnostics yielded electron number densities of about 5.9×10¹⁰cm^-3, 2.8 ×10¹⁰cm^-3and  1.8 ×10¹⁰cm^-3at  pressures  of  0.2,  0.5  and  2.5  Torr,  respectively.  The corresponding  densities  measured  with  the  hairpin  resonator  probe  were  4.8×10¹⁰cm^-3,  3.8 ×10¹⁰cm^-3 and 2.6 ×10¹⁰cm^-3. Discrepancies between the two techniques were within 30% and can be attributed mainly to inaccuracies in the sheath thickness estimation required the hairpin resonator probe results.</p>

Hydrophobic coatings find application in various sectors of the economy including to electronics, textiles, optical devices, and in scientific and commercial equipment. These different applications demand that different hydrophobic coatings posses a range of properties that may include smoothness or roughness, thicknesses on the order of a monolayer or a micron, robustness or the ability to dissolve quickly, transparency or opacity, water resistance or water permeability, electrical conductivity, oleophobicity, etc. However, whatever the final/desired properties, deposition via dry-deposition processes offers significant advantages, including greater reproducibility, increased environmental friendliness, and cost effectiveness on an industrial scale. Herein I explore the chemical vapor deposition of silanes and the characterization of a commercial, hydrophobic coating to better prepare and understand hydrophobic coatings on different materials. One of the characterization techniques I used frequently in these studies is X-ray photoelectron spectroscopy (XPS). Accordingly, in Chapter 2 of this thesis I discuss this technique vis-à-vis the chemical shifts it detects, which reflect the oxidation states of materials being probed. In particular, I discuss a recommendation made over a decade ago by Gion Calzaferri for 'fixing' the problem of oxidation numbers as applied to organic materials and show how XPS confirms his suggestion. In Chapter 3 I introduce hydrogen as an etch/cleaning gas for silicon wafers. I first show that, like argon and oxygen plasmas, hydrogen plasmas will effectively clean silicon wafers. However, I then show that hydrogen plasma treatment leads to a silicon surface that is chemically different than those prepared with the other plasmas and that undergoes silanization to a greater extent -- the resulting surfaces have higher water contact angles and thicknesses. In Chapter 4 I study the deposition of a potential barrier layer for water, which was prepared from an aza silane: N-n-butyl-aza-2,2-dimethoxysilacyclopentane (1) in a molecular layer deposition (MLD)-like process using either water or ammonium hydroxide as the second half reactant. This molecule has the interesting property of undergoing self-limiting growth, where the termination of this growth is accelerated by use of an ammonium hydroxide catalyst. Interestingly, films of 1 are considerably thicker on nylon than on silicon, which is explained by nylon acting as a water reservoir in the reaction. In Chapter 5 I show the careful characterization of the hydrophobic coating on an Apple iPod nano, which was probed by ToF-SIMS, wetting, and XPS. I could identify that the coating is only applied to the touchscreen of the device. SIMS suggested that the fluorinated coating contains oxygen, which should add to its biodegradability. Finally, in Chapter 6 I make recommendation for future work in these areas.

The presented thesis is focused on a spectroscopic study of unstable radicals, ions and molecules in a positive column glow discharge and laser plasma. The research of these fragments is supplemented by a study of biomolecules formation from these species and influence of catalysts. Molecular dynamics of radicals, ions and unstable molecules has been studied using a time resolved Fourier transform infrared spectroscopy. Time resolved spectra of CH4, HCONH2, BrCN, CH3CN, CF3Br, (CF3)2CHBr positive column glow discharges have been measured and simulated using a kinetic model including molecular dynamics, collisions and chemical and radiation transfer processes. The model has been compared with our experimental results and time resolved spectra were described in details. Fit to a complex reaction mechanism has been used to estimate a rate constant of a HCN conversion to HNC by a collision with H radical. The study of precursors of biomolecules was focused on chemical consequences of a laser induced dielectric breakdown in formamide vapor and gaseous carbon monooxide with 18 O labeled water. Dissociation products have been detected using the Fourier transform absorption spectroscopy. The experimental results have been explained by a help of a chemical laser spark dynamics model. Additionally, our the...

Verunreinigungen von Fremdelementen können den Wirkungsgrad von Solarzellen schon im Spurenbereich beeinträchtigen. Die Kenntnis der Verunreinigungen in Si ist entscheidend für die Produkt- und Produktionskontrolle neuer Solarzellenmaterialien. In dieser Arbeit wurden Analysenmethoden mit unterschiedlichen Messverfahren unter besonderer Berücksichtigung der Ansprüche der Solarindustrie entwickelt, verbessert, charakterisiert und verglichen. Mit der Sektorfeld-Massenspektrometrie (SFMS) mit induktiv gekoppeltem Plasma (ICP) nach Matrixabtrennung konnten 22 Elemente mit Bestimmungsgrenzen bis zu 120 pg g−1, quantifiziert werden. Das neue Verfahren erlaubte die Bestimmung aller Elemente in einem Analysengang ohne Analytverlust. Dabei wurde ein bisher in der Literatur nicht beschriebener Mechanismus aufgeklärt, welcher die Retention von Bor im Matrixverdampfungsschritt ohne Zusatz von Komplexbildnern erlaubt. Mit der Glimmentladungs-(GD )MS wurden 32 Elemente bis in den sub ng g−1-Bereich bestimmt. Es gelang, relative Empfindlichkeitsfaktoren zur Quantifizierung von B, P, As, Ga, Ge und Fe zu errechnen. Methoden basierend auf der elektrothermischen Verdampfung (ETV), gekoppelt an ICP-MS und ICP-Emissionsspektroskopie (OES) sowie Gleichstrombogen-OES wurden zur Charakterisierung von metallurgischem Si-Pulver mit Gehalten im µg g−1-Bereich verwendet. Die Totalreflexion-Röntgenfluoreszenz wurde als Volumenmessmethode für die Si-Analytik eingesetzt. Komplettiert wird das Methodenspektrum durch Oberflächenanalytik von Wafern mittels Laserablation-(LA)-ICP-MS. Es wurden erstmalig für Silicium Konzepte zur quantitativen Bestimmung der Verunreinigungen auf Si-Wafern über eine Kalibrierung der LA mit eingetrockneten flüssigen Standards erarbeitet und gezeigt, dass sich das Verfahren zum Nachweis typischer metallischer Ausscheidungen eignet. Die Neutronenaktivierungsanalyse wurde als anerkannte Referenzmethode der Halbleiterindustrie zur Validierung der Methoden eingesetzt. / Element impurities can affect the efficiency of solar cells already on the trace level. The knowledge of the impurities in Si is thus crucial for the product and production control of new solar cell materials. In this work, analysis methods based on different measurement principles have been developed, improved, characterized and compared with special consideration of the requirements of the solar industry. Sector field mass spectrometry (SFMS) with inductively coupled plasma (ICP) subsequent to matrix separation has been used to determine 22 elements with limits of determination down to 120 pg g−1 on sample basis. The new, optimized procedure allowed the determination of all analytes in one sweep without analyte loss during the evaporation step. A so-far unexplained mechanism for the retention of boron without use of additional complexing agents was elucidated. Glow discharge (GD)MS was used to measure 32 elements down to the sub-ng g−1 range. Relative sensitivity factors for the quantification of B, P, As, Ga, Ge and Fe have been calculated. Methods based on electrothermal vaporization (ETV) coupled to ICP-MS and ICP emission spectroscopy (OES) as well as direct current arc OES were used for the characterization of metallurgical grade Si powder with concentrations in the µg g−1 range. Total reflection X-ray fluorescence was used as a method for bulk impurity concentration analysis. The spectrum of methods is complemented by surface analysis of silicon wafers by laser ablation (LA)-ICP-MS. New concepts for quantitative analysis of silicon surfaces by the calibration of LA with dried liquid standards were elaborated. It has been demonstrated that this method is suitable for the detection of typical metallic precipitations in silicon like copper silicide. For validation of the methods, instrumental neutron activation analysis was used as the generally accepted reference method in the semiconductor industry.

Made available in DSpace on 2017-07-21T19:26:00Z (GMT). No. of bitstreams: 1 Andre Assmann.pdf: 3125745 bytes, checksum: 38854736eae2fcc4e8c2c21a2668f387 (MD5) Previous issue date: 2011-04-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In the present work showing the results on mechanical and tribological properties of duplex stainless steel LDX2101 nitriding by Ion Implantation (II), Plasma Immersion Ion Implantation (PI3) and Glow Discharge (GD). Nitrogen ion implantation was performed at room temperature and 350 C. The nitrogen fluencies were combined to obtain an atomic nitrogen concentration of 27 %. The PI3 was carried out with temperatures of 300 and 350 C working in N2 atmosphere during 3 hours. For GD, the working conditions were gas mixture N2/H2 (in the ratio 80%/20%, 60%/40% and 20%/80%) and N2/CH4 (in the ratio 98%/02%) during 3 hours at temperatures of 300, 350 and 380 C. Structural characterizations of the modified layers were performed by X-Ray Diffraction (XRD) with Bragg-Brentano geometry. Hardness was obtained by instrumented indentation using Oliver and Pharr method’s with Berkovich indenter. Tribological tests were evaluated by reciprocating sliding with a WC(Co) sphere (counter body). XRD patterns for II samples showing only the formation of γN, however, samples treated by GD and PI3 showed the formation of γ’Fe4N and Fe2+XN, over there γN, as a function of the working temperature and nitriding atmosphere. After the nitriding hardness values between 8 and 20 GPa in comparison to 3 GPa of the bulk was obtained. The hardness profile of samples treated by GD at 350 and 380 C exhibit plateaulike for values of hardness between 13 and 20 GPa, indicate the formation of a thicker nitrited layer. The friction coefficient for II samples showed a strong adhesive wear. PI3 samples exhibit long running-in regimes compared to II and untreated samples. GD samples showing a predominant abrasive wear because ploughing of surface for asperities and wear particles formed between the surface and counter body. The significant decrease in the wear was observed in all GD samples, with a reduction of one order of magnitude compared to untreated sample. / No presente trabalho, são apresentados os resultados sobre as propriedades mecânicas e tribológicas do aço inoxidável duplex LDX 2101 nitretado por Implantação Iônica (II), Implantação Iônica por Imersão em Plasma (3IP) e Descarga Luminosa (DL). A Implantação Iônica de nitrogênio foi realizada em temperatura ambiente e em 350 C. As fluências utilizadas foram combinadas para obter uma concentração de átomos de nitrogênio de 27 %. A nitretação 3IP, foi realizada nas temperaturas de 300 e 350 C em atmosfera de N2 durante 3 horas. Para o tratamento por DL as condições de tratamento foram em diferentes atmosferas de N2/H2 (nas proporções de 80%/20%, 60%/40% e 20%/80%) e N2/CH4 (na proporção de 98%/02%) durante 3 horas nas temperaturas de 300, 350 e 380 C. A caracterização estrutural das camadas modificadas foi obtida através de Difração de Raios-X (DRX) com geometria Bragg-Brentano. Os perfis de dureza foram obtidos por indentação instrumentada usando o método de Oliver e Pharr com indentador do tipo Berkovich. Testes tribológicos foram realizados com tribômetro do tipo pino sobre disco em movimento recíproco com uma esfera de WC(Co) de contra corpo. Os padrões de DRX para amostras tratadas por II apresentaram apenas a formação de γN, contudo, as amostras tratadas por DL e 3IP apresentaram a formação de γ’-Fe4N e Fe2+XN, além de γN, como função da temperatura de tratamento e da atmosfera de nitretação. Após as nitretações durezas entre 8 e 20 GPa em comparação a 3 GPa para o substrato foram obtidas. Perfis de dureza para amostras tratadas por DL em 350 e 380 C exibiram valores entre 13 e 20 GPa em forma de platô, indicando a formação de uma espessa camada nitretada. O coeficiente de atrito para as amostras tratadas por II apresentaram um forte desgaste adesivo. Amostras tratadas por 3IP exibiram longos regimes de acomodação comparados as amostras tratadas por II e a amostra referência. Amostras tratadas por DL apresentaram um predominante desgaste abrasivo devido à deformação plástica da superfície causada pelas asperidades e pelas partículas de desgaste formadas entre a superfície e o contra corpo. Uma significante diminuição no desgaste foi observada em todas as amostras tratadas por DL, com uma redução de uma ordem de grandeza quando comparado a amostra sem tratamento.

Dans ce travail, nous proposons une approche essentiellement expérimentale. Dans une première partie, nous exposons les résultats obtenus par imagerie rapide et mesures électriques corrélées dans le temps, concernant l’étude de la transition entre des électrodes de cuivre dans l’air et l’argon, et entre des électrodes de tungstène dans l’argon pour des pressions comprises entre 100 mbar et 1 bar. Dans aucun cas une transition à l’arc n’est observée sans constriction quasi-totale de la colonne positive. Dans le cas d’électrodes en tungstène dans l’argon, la vitesse d’extension de la zone filamentaire depuis l’anode vers la cathode a été vue dépendante de la pression et de l’intensité. La durée d’une transition spontanée a été linéairement corrélée à la distance inter-électrode, suggérant un mécanisme propagatif à vitesse constante dans la colonne. Plus la pression est élevée, plus la durée totale des transitions est longue ; par ailleurs, à pression constante, cette durée de transition spontanée décroît à intensité croissante, pour tendre vers une durée limite, correspondant à la durée constante de changement de structure de la zone cathodique. Dans une seconde partie, nous nous intéressons à l’échauffement de surfaces d’anodes et de cathodes en cuivre dans l’air et dans l’argon soumises à des arcs électrique pour plusieurs gammes de courant (de 30 à 120 A). Deux méthodes de mesures sont utilisées. Enfin, nous utilisons les mesures de températures de surface pour proposer deux modèles simples de bilan de puissance à la surface des électrodes (flux de chaleur). L’un considère uniquement le chauffage dû au spot d’arc et l’autre le chauffage supplémentaire de la colonne d’arc. / In this work, an approach which is essentially experimental is proposed. In the first part, results are presented which were obtained by synchronized fast camera imaging and electrical measurements. These concern the study of the transition between copper electrodes in air and in argon, and between tungsten electrodes in argon for gas pressure in the range 100 mbar – 1 bar. In no case was the transition to arc been observed without the quasi-total constriction of the positive column. Considering tungsten electrodes in argon, the propagation speed of the filamentary part of the positive column from the anode to the cathode was found to be dependent on the gas pressure and the discharge current intensity. During spontaneous transition, the transition duration has been linearly correlated to the electrode gap, suggesting a propagative mechanism with a constant speed. The higher the pressure, the longer is the total transition duration. For a constant pressure and discharge current, the duration of spontaneous transition decreases with decreasing gap distance toward a limiting value, which corresponds to the constant duration of the structural change of the cathode root from diffuse to spot. In the second part, heating of copper anodes and copper cathodes submitted to electric arcs in air and in argon and for various current intensity values (from 30A to 120 A) is considered. Two measurement methods are used. Finally, the surface temperature measurements are used to purpose two models of the electrode surface power balance (heat flux). One model only considers the heating due to the arc spot and the second one considers a supplementary heating from the arc column.

Les décharges contrôlées par barrière diélectrique (DBD) homogènes à pression atmosphérique sont une alternative pour réaliser des couches minces sur de grandes surfaces, en continu, sans système de pompage. La physique de ces décharges tout comme les propriétés des couches minces obtenues sont bien établies en excitation sinusoïdale basse fréquence (< 200 kHz) et radiofréquence (13,56 MHz). L’objet de cette thèse est d’étendre le domaine de fonctionnement de ces décharges dans un mélange Penning Ar/NH3. Pour ce faire, un dispositif original a été mis au point permettant de faire varier la fréquence d'excitation en tension sinusoïdale entre 50 kHz à 18 MHz. La DBD nanopulsée répétitive a également été étudiée. L’objectif est d’identifier de nouveaux modes de fonctionnement de la DBD homogène et d’en maximiser la puissance pour augmenter la vitesse de dépôt de couche mince tout en maintenant une qualité compatible avec les applications. Dans un mélange Ar-NH3, le régime de fonctionnement de la décharge transit de luminescent (GDBD) à Townsend (TDBD) vers 250 kHz puis à RF-DBD à partir de 3 MHz. Les mesures électriques et optiques qui ont été réalisées montrent que la puissance moyenne des décharges homogènes augmente d'un facteur 30 entre les régimes GDBD et RF-DBD (jusqu'à 35 W/cm3) tandis que la tension d'amorçage est réduite d'un facteur 6. Ces observations couplées aux spectres d’émission des décharges indiquent que la densité d’électrons augmente de plusieurs ordres de grandeur alors que leur énergie décroit. Ces résultats s’expliquent par un changement de mécanisme d'ionisation avec un rôle dominant de l'émission d'électron secondaire à la cathode en basse fréquence (GDBD et TDBD) tandis que l'ionisation en volume domine en RF-DBD. Les deux transitions entre les régimes GDBD-TDBD et TDBD-RF-DBD sont étudiées. La première est liée au temps de transit des ions de l'anode vers la cathode qui devient plus long que la demi-période. En conséquence, la chute cathodique ne se forme pas. La deuxième transition est liée au piégeage des ions puis des électrons qui dépend de la tension appliquée, de la valeur de l'espace interélectrode et de la fréquence. Ces régimes de décharges sont comparés au régime nanopulsé répétitif (NPR-DBD). Les conditions conduisant à une décharge homogène ont été trouvées. La puissance maximale en régime homogène est de 17 W/cm3 ce qui est 17 fois plus élevé que pour un régime sinusoïdal à même fréquence. Elle est obtenue pour une fréquence de répétition de 30 kHz avec un pulse de tension de 10 ns. Les dépôts de nitrure de silicium et d’oxyde de silicium obtenus à partir de SiH4 avec des GDBD, RF-DBD et NPR-DBD ont été étudiés. Dans tous les cas, la vitesse de dépôt est définie par la puissance de la décharge. L'augmentation de la puissance de la décharge avec la fréquence permet d'augmenter la vitesse de dépôt de 30 à 90 nm/min. Néanmoins avec l'utilisation de silane à température ambiante, des nanoparticules se forment en RF lorsque la puissance de la décharge est forte. La modulation d'amplitude empêche la formation des poudres. Pour ce faire l'énergie injectée pendant le Ton doit être inférieure à 100 µJ. Comme les précurseurs ne sont plus consommés par la formation de poudres, ils sont disponibles pour la croissance de la couche ce qui double la vitesse de dépôt par rapport au continu pour la même puissance moyenne. L'augmentation de la vitesse de dépôt sans poudre avec la puissance moyenne nécessite une augmentation de la fréquence de modulation (> 1 kHz) ce qui implique un Ton de plus en plus court pour limiter l'énergie injectée.Ce travail a mis en évidence un nouveau régime de décharge, la TDBD, en Ar-NH3. Il a permis de comparer les GDBD, TDBD, RF-DBD et NRP-DBD dans la même configuration de décharge. Pour la première fois des dépôts de couches minces ont été faits par RF-DBD et il a été montré que la modulation du plasma peut augmenter significativement la vitesse de dépôt. / The homogeneous discharge controlled by dielectric barrier at atmospheric pressure and their applications are a promising field of activity because of their advantages in contrast with the low pressure processes, especially for the on line treatment of large surface without pumping system. The physics of these discharges as the thin film properties obtained are well established with low frequency sinusoidal (<200 kHz) and radiofrequency excitation (13.56MHz). This is what is explored in this thesis aimed to find and explore new modes of homogeneous DBD and maximizing the power to optimize the deposition rate while maintaining quality thin layers. To achieve this goal, an original device has been developed varying the excitation frequency from 100 kHz to 18 MHz. The frequency increase on this range have many consequences. In an Ar-NH3 mixture, the discharge regime becomes successively a glow (GDBD) then Townsend (TDBD) around 250 kHz then RF-DBD from 3 MHz. The electrical and optical measurements that have been done show that the average power of the homogeneous discharges increases by a factor of 30 between GDBD regime and RF-DBD regime (up to 35 W/cm3) while the breakdown voltage is reduced by a factor 6. These observations coupled to the discharge emission spectra indicate that the electron density increases by several orders of magnitude while their energy decreases. These results are due to a change of the ionization mechanism with a dominant role of the secondary electron emission at the cathode in low frequency regime (GDBD and TDBD) while the volume ionization is dominate in RF-DBD. Both transitions between GDBD-TDBD regimes and TDBD-RF-DBD are studied. The first is related to the ion transit from the anode to the cathode which becomes longer than the half-period. In consequence, the cathode fall is not formed. The second transition is related to ions and electrons trapping which depends on the applied voltage, the value of the inter-electrode space and frequency.These discharges regime are compared to Nanopulsed repetitively discharge (NPR-DBD). The conditions leading to a homogeneous discharge are found. In homogeneous regime the maximum of the discharge power is 17 W/cm3 which is 17 times higher than for a low sinusoidal voltage for the same frequency. It is obtained for a repetition frequency of 30 kHz with a 10 ns voltage pulse. Hydrogenated silica and silicon nitride thin film obtained from SiH4 with GDBD, RF-DBD and NPR-DBD were studied. In all cases, the deposition rate is defined by the discharge power. The increase of the discharge power with the frequency increases the deposition rate from 30 nm/min to 90 nm/min. However with the use of silane at room temperature, nanoparticles are formed in RF regime when the discharge power is high. The amplitude modulation allows to prevent the formation of powders. AS far as the energy injected during Ton is less than 100 μJ. As the precursors are not consumed by the formation of powders, they are available for the growth of the layer thereby doubling the deposition rate compared to the continuous process for the same average power. Increasing the growth rate without powders with the average power requires an increase in the modulation frequency (> 1 kHz) i.e. a short Ton to limit the injected energy. Thus this work has highlighted a new discharge regime, the TDBD in Ar-NH3 and compared the GDBD, TDBD, RF-DBD and NRP-DBD discharge in the same configuration. For the first time, RF-DBD coating have been made and it has been shown that modulation of plasma, although it decreases the discharge power, can significantly increase the deposition rate.

Im Rahmen der Dissertation wurden mit der Glimmentladungs-Spektrometrie Materialproben untersucht, die Wasserstoff enthalten. Auch sehr geringe Gehalte, z.B. im µg/g-Bereich, können nachgewiesen werden. GD-OES ist oft die einzige Methode, die für diese analytische Aufgabenstellung zur Verfügung steht. Die Anwesenheit von Wasserstoff im Glimmentladungsplasma bewirkt verschiedene Effekte: (i) die Signalintensitäten der meisten analytischen Emissionslinien und der des Trägergases werden beeinflußt, (ii) aus dem Wasserstoffkontinuum resultiert ein erhöhter spektraler Untergrund, (iii) der elektrische Widerstand des Plasmas steigt und (iv) die Abtragsraten sinken. Zum Verständnis dieser Effekte werden grundlegende Untersuchungen zu den Anregungs- und Ionisationsmechanismen im Glimmentladungsplasma durchgeführt. Da es keine geeigneten Materialien gibt, für die der Gehalt an Wasserstoff stabil sind, wurden die Wasserstoffeffekte und die Möglichkeit des Nachweises von Wasserstoff durch Zugabe wohl definierter Mengen gasförmigen Wasserstoffs in das GD-Plasma simuliert. Für die Änderungen (i) de Analyt- und Trägergassignale, (ii) des Entladungsstroms als abhängigen GD-Pa-rameter sowie (iii) des Wasserstofflinien- und Kontinuumspektrums wurde experimentell festgestellt, dass sie sehr ähnlich sind, unabhängig davon, ob der Wasserstoff aus der Probe kommt oder als Gas ins Plasma eingeleitet wird. Die Anwesenheit von Wasserstoff im GD Plasma beeinflußt die Form des Abtragskraters, durch den die Tiefenauflösung bestimmt wird. Dieser Effekt kann gezielt bei nichtleitenden Schichtmaterialien genutzt werden, um die Tiefenauflösung zu verbessern. Weiterhin können Empfindlichkeit und Nachweisgrenze von bestimmten Emissionslinien eines Analyten verbessert werden. Der Was-serstoff im elektrolytischen (Cd- oder Zn-)Schichtsystem kann die Materialeigenschaften ver-schlechtern. Beispielhaft sei die Versprödung genannt. Mit der GD-OES Tiefen-profilanalyse kann die Wirkung thermischer Nachbehandlungen, die in der Technik üblich sind, verfolgt werden. Es konnte an praktischen Beispielen gezeigt werden, dass für erfolgreiche Anwendungen der GD-OES für Dünnschichtanalytik die Reinheit (d.h. minimale H-Effekte) der GD-Quelle von entscheidender Bedeutung ist.

Ces dernières années, les missions spatiales bénéficient d'un regain d'intérêt. Cependant, lorsqu’arrive laphase d’entrée dans l’atmosphère, nous faisons encore face à d’importantes difficultés. Afin de répondre àce problème, une nouvelle technique est proposée : le contrôle par plasma pour augmenter la force detraînée sur le véhicule et ainsi, décroître sa vitesse. Dans cette thèse, un actionneur plasma est testé danstrois écoulements supersoniques (N1(M2-8Pa), N2(M4-8Pa) and N3(M4-71Pa)) et un hypersonique (M20-0.062Pa), ces écoulements étant simulés par la soufflerie MARHy.L’actionneur plasma induit des modifications de l’écoulement autour du modèle étudié, comme unemodification de la géométrie de l’onde de choc et une augmentation de l’angle de choc. Afin de mieuxcomprendre les phénomènes gouvernant ces modifications, la pression Pitot, la température surfacique etvolumique, les données électroniques et des mesures spectroscopiques ont été analysées. Les résultatsmontrèrent que deux types d’effets interviennent : thermiques (surface et volume) et l’ionisation. De plus, il aété démontré que ces effets n’ont pas la même importance suivant les conditions d’écoulements.L’actionneur plasma lui-même a été modifié dans un but d’amélioration. En particulier, deux types degénérateurs ont été étudiés pour alimenter la cathode : DC et pulsé. Finalement, il est montré que pour unepuissance de décharge de 80 W, une augmentation de 13% de la traînée et donc, une diminution de plus de25% des flux de chaleur peuvent être attendus. Par conséquent, les actionneurs plasma semblent être descandidats idéaux pour les missions spatiales et les (r)entrées atmosphérique. / Space missions are arousing renewed interest in these recent years. However, when coming to the entryinto the atmosphere, major issues are still to be considered. To answer this problem, a new Entry DescentLanding technique is proposed: plasma actuation to increase the drag force over the vehicle body and thus,decrease its speed. In this thesis, a plasma actuator is tested in three supersonic rarefied flows (N1(M2-8Pa), N2(M4-8Pa) and N3(M4-71Pa)) and a hypersonic one (M20-0.062Pa), all generated by the wind tunnelMARHy.The plasma actuator induces flow modifications over the studied model, such as a change in the shock waveshape and an increase in the shock wave angle. In order to better understand the phenomena governingthese modifications, Pitot pressure, surface and gas temperature, electron data and spectroscopicmeasurements were analyzed. The results shown that two types of effects are involved: thermal (bulk andsurface) and ionization. Moreover, it was demonstrated that these effects had not the same importancedepending on the flow conditions.The plasma actuator was also modified in order to improve it. In particular, two types of generators wereused to biase the cathode: DC and pulsed. Finally, it was shown that, for a discharge power of 80 W, a 13%increase in the drag force could be expected and thus, a decrease in the heat load over the model body ofmore than 25%. Therefore, plasma actuators seem to be promising applications for space missions andatmospheric entries.