Literatura científica selecionada sobre o tema "Plasma radiofréquence"
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Teses / dissertações sobre o assunto "Plasma radiofréquence"
Mohamed, Salem Ould Mohamed. "Etude fondamentale et adaptation à la pulvérisation cathodique d'un réacteur à plasma radiofréquence". Pau, 1997. http://www.theses.fr/1997PAUU3020.
Texto completo da fonteMarques, Luís Silvino Alves. "Modélisation et caractérisation de décharges radiofréquence à couplage capacitif dans l'hydrogène". Paris 11, 2005. http://www.theses.fr/2005PA11A002.
Texto completo da fonteThis work presents the modelling and the characterization of capacitively-coupled radio- frequency discharges in hydrogen, produced within a cylindrical parallel-plate reactor. The discharge characterization covered a wide range of excitation frequencies (13,56-80. 0 mhz). Gas pressures (0. 2 - 6 torr) and applied rf voltages (50-800 v), and used a state of art two-dimensional fluid model (to describe the dynamics of electrons, positive ions h+, h2+, h3+ and negative ion h- in the reactor), self-consistently coupled to a homogeneous collisional-radiative model for hydrogen (including a very complete kinetic scheme involving vibrationally excited molecular species and electronically excited atomic species). There is a good agreement between calculated results and experimental measurements for the coupled electrical power and the plasma potential. However, model predictions for the electron density and the self-bias voltage show only a qualitative agreement with experiment, with calculated values understimated with respect to measurements. This qualitative disagreement is only slightly dependent of the kinetic scheme adopted, and probably is a direct consequence of the homogenous model describing the transport of neutral species. To clarify this, a two-dimensional hydrodynamic gas model is developed based on the navier-stokes equation system plus a multicomponent reactive mass transport module. This innovative model is the key part of a powerful predictive tool, to be used in the optimisation of plasma reactors for material processing
Zahri, Abdellatif. "Développement du modèle PIC-MCC 2D : application aux décharges radiofréquence". Toulouse 3, 2010. http://thesesups.ups-tlse.fr/1344/.
Texto completo da fonteThe particle-in-cell method combined with the Monte Carlo techniques is a well established method for plasma modelling, and is widely used to simulate low pressure radiofrequency discharges. This technique is a simple and effective method for solving a wide variety of complex problems involving a large number of particles moving under the action of internal forces and external forces (electromagnetic fields. . . ) The purpose of our model is to understand and characterize the behaviour of low pressure plasmas in a two-dimensional geometry. We want to understand what is happening in the sheath and in particular the behaviour of the ions. In this work, we describe the PIC-MCC models and techniques needed to build such models. We chose this technique by its ability to describe correctly the plasma physics at low pressure. Indeed, this technique provides more details without any assumption on the distribution function of electrons or ions, which is far from being the case for other models including fluid models. We show some distribution functions (density and energy of charged particles, EEDF) ; the electrical characteristics of the discharge are presented. This work is part of the European project EMDPA : New Elemental and Molecular Depth Analysis of advanced materials by modulated radio frequency glow discharge time of flight mass spectrometry. This project is funded by the European Commission through the research program for technological development
Glad, Xavier. "Synthèse et étude de la formation de pyramides et cônes de graphite par gravure en plasma radiofréquence argon/hydrogène". Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0127/document.
Texto completo da fonteCarbon 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
Bouanis, Fatima Zahra. "Amélioration des propriétés anticorrosion d’un acier au carbone par nitruration par plasma froid radiofréquence". Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10183.
Texto completo da fonteThe aim of this work concerns the study of the improvement of the corrosion resistance in acidic medium (1M HCl) and mechanical properties of carbon steel (XC38) using a radiofrequency cold plasma nitriding process. The originality of this work consists in nitriding substrates using nitrogen cold plasma, where the process temperature is roughly ambient temperature and without heating the substrate. The nitriding was carried using nitrogen and nitrogen/ hydrogen plasma gas mixtures. The hydrogen role in the plasma consists not only in reducing the iron oxide layer on the substrate, but also accelerates the nitrogen diffusion in the substrate. Surface characterizations performed by means of the Electron Probe Microanalysis (EPMA) and X-ray Photoelectron spectroscopy (XPS) indicate that the treatment plasma induces the formation of a layer where the nitrided thickness is higher than ten microns for long treatment times (8h). The mechanical properties were studied by Vickers microhardness. The surface microhardness of the nitrided steel increases as the plasma processing time increases to reach a maximum of 1057Hv0.005 for the nitrided sample that was treated during 8h, when compared to sample untreated (247Hv0.005). The improvement of the corrosion resistance properties were investigated by gravimetric and electrochemical techniques such as potentiodynamic polarisation curves and electrochemical impedance spectroscopy (EIS) in 1M HCl medium. For the optimal conditions of treatment, the inhibition efficiency obtained is more than 95 % for 8h of treatment and remains constant for immersion times higher than 72h in aggressive medium (HCl 1M)
Goujon, Marjorie. "Modélisation et caractérisation expérimentale d'un procédé de dépôt de couches minces d'oxyde de silicium en plasma radiofréquence O2/HMDSO à basse pression". Vandoeuvre-les-Nancy, INPL, 2004. http://docnum.univ-lorraine.fr/public/INPL_T_2004_GOUJON_M.pdf.
Texto completo da fonteThe presented works deal with the investigation of a low pressure oxygen-hexamethyldisiloxane radio- frequency plasma assisting a chemical vapour deposition process used to deposit silicon oxide thin films onto metallic substrates. The first step consists in developing a fluid model to describe the plasma behaviour over a RF period. A particular attention is pa id to the time variation of the electric field and the charged particle densities. Moreover, the relative influence of the electrode ion bombardment and the wave-riding process on the secondary electron creation is pointed out and helps determine working conditions where ion impingement on the electrodes is reduced. Ln a second step, the plasma is studied by means of optical emission spectroscopy and Fourier transform infra-red absorption spectroscopy (FTIR). From the experimental results, the dissociatio~ rate of the organo-silicon monomer is estimated and valuable insights into the dissociation mechanisms of the organic precursor are obtained. FTIR analyses of the deposited films are carried out and coupled with the gas phase characterization, providing correlations between the film and the plasma compositions. These results are completed by a kinetic modelling of the neutral species in the 02/HMDSO plasma. This numerical simulation corn putes the variation of the main species density over the inter-electrode space and especially in the close vicinity of the substrate, allowing prediction of the carbon incorporation in the films
Bousquet, Angélique. "Dépôt de couches minces par plasma pulsé radiofréquence et basse pression en mélange hexaméthyldisiloxane / oxygène". Nantes, 2005. http://www.theses.fr/2005NANT2084.
Texto completo da fonteThis work concerns the Plasma Enhanced Chemical Vapour Deposition (PECVD) of thin films, at low pressure (3mTorr) and low temperature (<100°C), in Hexamethyldisiloxane (HMDSO)/ oxygen pulsed plasmas in a radiofrequency helicon reactor. The kinetics of charged species and of some neutral active species is investigated by Langmuir probe and optical emission spectroscopy time-resolved measurements. The film analysis by ellipsometry, infrared spectroscopy and gravimetry shows inorganic SiO2-like and plasma polymers SiOxCyHz films can be deposited with a fixed gas mixture depending on the pulse parameters. The structure and deposition rate are linked to the creation and loss times of oxygen atoms. The reduction of ion bombardment in pulsed plasma also allows to reduce the compressive stress and to improve the electrical properties of SiO2-like films, as demonstrated by nano-indentation, Newton's ring method, and C(V) and I(V) measurements on MOS structure
Pereira, Jérémy. "Analyse et comportements des particules créées dans un plasma radiofréquence basse pression en mélange méthane/azote". Orléans, 2007. http://www.theses.fr/2007ORLE2032.
Texto completo da fonteBoudhib, Mohamed. "Analyse d’aérosols par méthodes LIBS sans étalonnage et LIBS couplée à une cellule radiofréquence utilisée comme piège à particules". Thesis, Orléans, 2017. http://www.theses.fr/2017ORLE2011/document.
Texto completo da fonteNew issues related to process control and workplace surveillance accompany the emergence of nanotechnology industry. This involves the development of new real-time and in-situ characterization techniques. In this context, the NOVA unit from the INERIS institute collaborated with LP3 and GREMI laboratories to study two approaches aiming to enhance the LIBS technic performances. The first approach used a flow cell to determine the relative elemental composition of an aerosol with a calibration-free procedure. The recorded spectra were compared to theoretical spectra calculated for a plasma in the Local Thermodynamic Equilibrium LTE. The best agreement between recorded and computed spectra allowed the determination of the relative composition with a good agreement with the reference value, for an alumina aerosol. The study of the temporal evolution of the plasma allowed the estimation of a temporal range within which the LTE hypothesis was verified. The second approach used a low-pressure radiofrequency plasma generated in an inert gas as a particle trap to analyse aerosols and nanoparticles. The use of such a system allowed the enhancement of particles detection by concentrating them spatially. We determined the optimal parameters for the LIBS analysis using this system. Furthermore, we established the plasma continuum was attenuated even at very low time delays. We evaluated the sampling volume of this new system and compared it to case of LIBS analysis on air. Finally, we estimated the detection limits of this system when analysing nanoparticles
Arbeltier, Steven. "Optimisation de dépôts de LIPON par pulvérisation magnétron RadioFréquence pour la fabrication de micro-batteries. Modélisation de l'interaction plasma-surface". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS170/document.
Texto completo da fonteThe scale reduction of batteries is a real technological challenge for the near future. These micro-batteries, about ten micrometers thick, are used to supply the power for small sized systems. LIPON is one of the most suitable electrolytes considered for industrial scale production. It is deposited in thin-film by radiofrequency magnetron sputtering of Li₃PO₄ in nitrogen plasma. This thesis is focused on particles behavior in plasma and during deposition. Optical emission spectroscopy and electron density measurements have been performed, to provide data used as input or validation for several numerical models. The first model describes plasma kinetics in the magnetron reactor, as 0D global model, and helps to identify the main chemical species and important reactions. This information has been useful to define a simplified kinetics for the second model, 2D, dealing with the charged species behavior in the plasma and describing target sputtering by ion bombardment. It provides the sputtered areas, ion energy and impinging angle onto the target. These obtained results have been employed in a 3D model that simulates sputtered atoms transport from the target to the substrate and predicting the thin-film features. Some characteristics of the target during sputtering have been highlighted and confirmed by the direct comparison between numerical and experimental results
Livros sobre o assunto "Plasma radiofréquence"
Topical Conference on Radio Frequency Power in Plasmas (12th 1997 Savannah, Georgia). Radio frequency power in plasmas: 12th Topical Conference, Savannah, GA April 1997. Editado por Ryan Philip M, Intrator Thomas e American Institute of Physics. Woodbury, N.Y: AIP Press, 1997.
Encontre o texto completo da fonteN, Shneider Mikhail, e Yatsenko Nikolai A, eds. Radio-frequency capacitive discharges. Boca Raton: CRC Press, 1995.
Encontre o texto completo da fonte(Editor), Ryan, e Intrator (Editor), eds. Radio Frequency Power in Plasmas: 12th Topical Conference (AIP Conference Proceedings). American Institute of Physics, 1998.
Encontre o texto completo da fonte