Teses / dissertações sobre o tema "Plasma radiofréquence"
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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
Thérèse, Laurent. "Plasmas radiofréquence pour l'analyse des matériaux : étude expérimentale, analytique et numérique". Toulouse 3, 2005. http://www.theses.fr/2005TOU30027.
Texto completo da fonteThe work presented in this thesis is a contribution to the comprehension of the discharge and the plasma used in radiofrequency optical emission spectroscopy at 13,56 MHz for the analysis of materials. The study is based on an experimental characterization of the discharge and the plasma. We have developed experimental diagnoses devices (electric and optical) allowing to measure the voltage, the discharge current, the power injected into the plasma in the case of conducting materials, and to measure the emission intensity of the argon line at 750,4 nm. We have developed a simple analytical model which starting from the electrical measurements gives access to informations on the fundamental properties of the plasma (maximum electric field, thickness of sheath, densities) and with which we also could determine an equivalent electric circuit of the discharge. This model enables us to characterize the evolution of the basic parameters of plasma according to the power, the pressure, the nature of material of cathode or anode. We have also used a hybrid digital model fluid Monte Carlo two-dimensional of the discharge which enabled us to validate the experimental and analytical results
Moguet, Fabrice. "Nature des liaissons C-F dans divers matériaux carbonés fluorés par voie gazeuse et par voie plasma radiofréquence". Phd thesis, Université Sciences et Technologies - Bordeaux I, 1996. http://tel.archives-ouvertes.fr/tel-00160008.
Texto completo da fonteMoguet, Fabrice. "Nature des liaisons C-F dans divers matériaux carbones fluorés par voie gazeuse et par voie plasma radiofréquence". Bordeaux 1, 1996. http://www.theses.fr/1996BOR10714.
Texto completo da fonteCherukulappurath, Mana Anil. "Measurement and modelling of heat fluxes received by a RF electrode in a magnetized plasma". Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0209.
Texto completo da fonteExcessive heating of the RF electrode/antenna due to high heat flux has detrimental impacts on fusion or plasma material processing perspectives. Acceleration of ions in the rectified potential in front of the RF antenna can sputter the material and create impurities inside the plasma. Heating due to electrons can raise the surface temperature and melt the material, eventually reducing the power coupling efficacy of the antenna. Since ion cyclotron resonance heating (ICRH) is one of the auxiliary heating mechanisms in modern fusion reactors and a new system is being developed based on capacitive coupling discharge for first mirror cleaning in tokamaks, investigations of particle flux/heat flux to the antenna/electrode surface in a magnetized RF environment has supreme importance. The presented thesis attempts to understand factors affecting heat flux by performing an experimental exercise and benchmarking the same with simple analytical/theoretical models. Experiments are performed in the ALINE (A LINEar) experimental device with three electrodes using two RF power coupling mechanisms (Direct and capacitive coupling). Sputtering experiments are performed using RF electrodes with a grounded copper wall. RF compensated Langmuir probe measurements revealed that the in-homogeneous sputtering pattern is due to the non-uniform distribution of the plasma density around the RF electrode caused by the drift and hot electron beams due to stochastic heating at the surface of the RF sheaths. This can also lead to non-uniform heating of the RF electrode. The heating of the RF electrode is measured using an IR camera, and heat flux is calculated using the code TEDDY for the one-faced tungsten and pure tungsten electrodes. In CCP mode, probe measurements near the one-faced RF electrode show positive bias and reversal of the electric field in front of the RF electrode at high magnetic fields and low pressures (0.6 Pa, 0.1 T). Higher heating of the RF electrode is observed when the bias is positive, meaning the positive bias can reduce the sputtering of the RF electrode by pushing the positive ions back into the plasma, but not the heating. Experiments with the tungsten electrode showed higher heating of the RF electrode in direct coupling than in capacitive coupling in all tilt angles
Andrieu, Michel. "Revêtements sur acier par PACVD radiofréquence et micro-onde : diagnostic de la phase gazeuse et optimisation de la tenue mécanique". Perpignan, 1997. http://www.theses.fr/1997PERP0267.
Texto completo da fonteCharles, Michaël. "Modélisation, conception et caractérisation d’un commutateur hyperfréquence à base de nanotubes de carbone verticaux". Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10024/document.
Texto completo da fonteSince their discovery, the properties of carbon nanotubes have been widely studied. The study of scientific relevance and feasibility of an ohmic and capacitive RF NEMS represents an area of research whose results would likely exceed the performances of RF MEMS. There are three switch designs, the cantilever, the bridge and the tweezer. This thesis offers a comprehensive study of RF NEMS switch in a tweezer configuration with a detailed explanation of all phases of modelization, fabrication and characterization. A literature search set the necessary theoretical elements for the knowledge and the consistency of this scientific process. Various experiments on the carbon nanotubes growth by PECVD method on a stack of different materials likely to compose the NEMS have been realized to result in a structure meeting the physical specifications of a NEMS RF and the thermal stress in PECVD synthesis (600°C to 800°C). The commutation experiments carried out on the NEMS switch illustrate the fabrication and the operation of these structures. The encouraging results in high frequency simulation and the fabrication of RF NEMS have brought credibility to the continuation of this work, with the objective of experimental measurements at high frequency in order to confirm or refute the theoretical models and the software simulations
Morscheidt, Willy. "Modélisation d'un réacteur RF à couplage capacitif en mélange Ar-O2 dans les conditions utilisées pour le procédé de dépôt par voie plasma d'oxyde d'étain". Paris 6, 2002. http://www.theses.fr/2002PA066266.
Texto completo da fonteVallée, Christophe. "Dépôt à basse température de couches minces d'oxyde de silicium élaborées en plasma oxygène / organosilicié dans un réacteur hélicon". Nantes, 1999. http://www.theses.fr/1999NANT2011.
Texto completo da fonteLouis, Yves. "Etude analytique et numérique de la réponse diélectrique non-locale d'un plasma de tokamak à une perturbation radiofréquence, tenant compte de la toroïdicité et des effets de décorrélation". Doctoral thesis, Universite Libre de Bruxelles, 1995. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212532.
Texto completo da fonteValt, Alexandre. "Étude de deux procédés de polymérisation d’un précurseur gazeux dans un plasma radiofréquence basse pression et liquide déposé sur un substrat activé par décharge à barrière diélectrique à pression atmosphérique : application aux propriétés antifouling". Paris 6, 2008. https://pastel.archives-ouvertes.fr/pastel-00004961.
Texto completo da fonteDumont, Rémi. "Contrôle du profil de courant par ondes cyclotroniques électroniques dans les tokamaks". Phd thesis, Université Henri Poincaré - Nancy I, 2001. http://tel.archives-ouvertes.fr/tel-00001589.
Texto completo da fonteAlcouffe, Grégoire. "Production d'équivalents d'aérosols de l'atmosphère de Titan par plasma radio-fréquence". Phd thesis, Versailles-St Quentin en Yvelines, 2010. http://tel.archives-ouvertes.fr/tel-00597792.
Texto completo da fonteAlcouffe, Grégoire. "Production d'équivalents d'aérosols de l'atmosphère de Titan par plasma radio fréquence". Phd thesis, Versailles-St Quentin en Yvelines, 2010. http://www.theses.fr/2010VERS0012.
Texto completo da fonteThe experiment prampre produces equivalents of aerosols of Titan's atmosphere thanks to a low pressure radio frequency plasma in a N2-CH4 gaseous mixture, representative of Titan's atmosphere, working in continuous or pulsed mode. The first goal of this work is to study the plasma. Electron density measurements, by microwave resonant cavity method, show this latter is lower in N2-CH4 mixtures than in pure N2. By optical emission spectroscopy, we show that this decrease in electron density is compensated by an increase in their energy. The second goal is a study of aerosols growth. Sem observations point out the influence of plasma parameters on the aerosols mean diameter between 300NM and 1µM. With 10S pulses, it is about 90NM, representative of Titan's aerosols. The pulsed mode shows that the formation time of aerosols is a few tens of seconds. This time is reduced at high pressure or at low amounts of CH4. At last, by measuring the polarization degree of the light of a 532NM laser beam scattered by aerosols, we can study their growth in situ and in real time. By comparing the measured polarization degree variations withe a mie-scattering model, we measure the evolution of aerosols mean radius and size distribution withe time. The obtained growth rates in radius of aerosols are about 4NM/S
Laurent, Christopher. "Caractérisation expérimentale et optimisation de procédés plasma pour la décontamination de l'AMC (Contamination Moléculaire Aéroportée)". Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30285.
Texto completo da fonteUn problème majeur en microélectronique est la contamination moléculaire aéroportée qui dégrade les substrats et les masques diminuant le rendement de production des composants. L'utilisation de boîtes de transport en polymères pour le stockage des substrats favorise la contamination moléculaire croisée entre les deux éléments. Il est alors primordial d'avoir un procédé de décontamination des boîtes efficace et rapide. Dans le cadre de cette thèse, plusieurs solutions de décontamination par plasmas ont été étudiées. Les plasmas étaient générés selon quatre couplages énergétiques en utilisant des excitations radiofréquence (13,56 MHz) et micro-onde (2,45 GHz). Ils étaient caractérisés avec une sonde de Langmuir et un spectromètre optique sous différentes conditions expérimentales. Enfin, un protocole de contamination au fluorure d'hydrogène a été développé pour évaluer et comparer l'efficacité de décontamination des procédés plasma à ceux utilisés actuellement en microélectronique
Dine, Sébastien. "Effet de la fréquence dans les décharges VHF sur les caractéristiques des plasmas utilisés pour le dépôt de silicium microcristallin". Phd thesis, Université Paris Sud - Paris XI, 2006. http://tel.archives-ouvertes.fr/tel-00305866.
Texto completo da fonteBelenguer, Philippe. "Modélisation des décharges radiofréquence en régime collilsionnel". Nancy 1, 1990. http://www.theses.fr/1990NAN10064.
Texto completo da fonteZeller, Philippe. "Étude expérimentale de la lueur négative et de l'espace cathodique d'une décharge à faisceau d'électrons". Paris 11, 1988. http://www.theses.fr/1988PA112254.
Texto completo da fonteSaulou, Claire. "Evaluation des propriétés anti-adhésives et biocides de films nanocomposites avec inclusions d’argent, déposés sur acier inoxydable par procédé plasma". Toulouse, INSA, 2009. http://eprint.insa-toulouse.fr/archive/00000315/.
Texto completo da fonteIn the biomedical domain and the food industry, microbial adhesion to surfaces generates multiple negative consequences, in terms of human health, hygiene and safety of processed food. In this context, our approach is based on developing a 316L stainless steel surface treatment, to prevent microbial colonization. The surface modifications, mediated by chemical or physical treatment, did not promote Saccharomyces cerevisiae detachment, evaluated in vitro using a shear stress flow chamber. The interactions between the microbial surface and metallic elements of the passive film were hypothesized to play a predominant role in this strong adhesion. An original and dual strategy, based on a plasma process associating hexamethyldisiloxane polymerization and silver target bombardment in an asymmetrical radiofrequency discharge, was carried out and optimized. Stainless steel surfaces were thus coated with nanocomposite thin films (~ 175 nm), composed of an organosilicon matrix, exhibiting anti-adhesive properties towards S. Cerevisiae, in which were embedded silver nanoparticles, displaying a high antimicrobial reactivity. A large set of complementary analytical techniques, operating at different scales, was used to correlate nanocomposite film characteristics with their anti-adhesive and antimicrobial efficiency. A total inhibition of yeast cell adhesion was achieved, by increasing the matrix polar character, through oxygen addition during the plasma process. In parallel, a 1. 9 log reduction in viable counts was achieved for sessile yeast cells. Further experiments were dedicated to the thorough understanding of cellular changes induced by silver release. A deterioration of the secondary structure of proteins (cell wall, intracellular), combined with ultra-structure alterations, was observed. In addition, the biocide activity of the nanocomposite film was confirmed against two prokaryotic models (Staphylococcus aureus and Escherichia coli). The necessity of a direct contact between microorganisms and coating was demonstrated for a maximal antimicrobial efficiency. Lastly, the durability of the coating properties was assessed through a repeated use of the nanocomposite films. A decrease in the antifungal activity, coupled to an anti-adhesive property enhancement, was noticed and explained by the silver release during the first use
Böhm, Christian. "Diagnostics et modélisation des décharges radiofréquences dans le silane et l'hélium". Palaiseau, Ecole polytechnique, 1992. http://www.theses.fr/1992EPXX0025.
Texto completo da fonteHbid, Tarik. "Modélisation et caractérisation expérimentale des décharges radiofréquence basse pression en présence de poudres". Toulouse 3, 1995. http://www.theses.fr/1995TOU30213.
Texto completo da fonteJacquot, Jonathan. "Description non linéaire auto-cohérente de la propagation d'ondes radiofréquences et de la périphérie d'un plasma magnétisé". Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0257/document.
Texto completo da fonteA correct understanding of the interactions between the edge plasma and the ion cyclotron (IC) waves (40-80MHz) is needed to inject reliably large amount of power required for self-sustainable fusion plasmas. These thesis objectives were to model separately, with Comsol Multiphysics, but in compatible approaches the wave coupling and the radio-frequency (RF) sheath formation to anticipate development of a single code combining both. Modelling of fast wave coupling requires a detailed description of the antenna (2D or 3D) and of the plasma environment by a full wave approach for a cold plasma. Absorption of outgoing waves is emulated by perfectly matched layers, rendered compatible with a plasma dielectric tensor. Experimental trends for the coupling resistance of the antennas of Tore Supra are qualitatively reproduced but the coupling efficiency is overestimated. In parallel a novel self-consistent description, including RF sheaths, of the interplay between the cold wave propagation and DC biasing of the magnetized edge plasma of a tokamak was developed with the minimum set of physics ingredients. For Tore Supra antenna cases, the code coupled with TOPICA allowed to unveil qualitatively some unexpected observations on the latest design of Tore Supra Faraday screens whose electrical design was supposed to minimize RF sheaths. From simulations, a DC (Direct Current) current transport appears necessary to explain the radial structures of measurements. Cantilevered bars have been identified as the design element in the antenna structure enhancing the plasma potential
Lee, Charles Anton. "Etudes expérimentales d'un plasma Hélicon". Toulouse 3, 2008. http://thesesups.ups-tlse.fr/394/.
Texto completo da fonteHelicon discharges produce peaked density profiles with radial density gradients creating a potential well that sets up Radially Localized Helicon (RLH) waves. This work presents new evidence that the RLH wave is the major power absorption mechanism in the plasma. We present experimentally measured density profiles in an argon helicon plasma used as input to a model which calculates the RF field structure. The actual experimental wave field structure is then compared to the model and compared to the RLH theory. Results from the experimental and model compare favorably with and are consistant with the RLH theory
Peng, Yan. "Synthèse et caractérisation de poussières carbonées dans une décharge radiofréquence". Thesis, Nancy 1, 2009. http://www.theses.fr/2009NAN10128/document.
Texto completo da fonteThe formation of carbon dust in tokamaks raises currently several real problems (safety, energy losses ...). To understand the mechanisms of these powders’ formation (size distribution, spatial distribution and transportation) and then find out a way to limit their role, an experimental study was carried out in a radiofrequency discharge Ar/C2H2. The plasma and these carbon powders were characterized by different techniques (optical emission spectroscopy, scattering of radiation, in-situ FTIR, fast camera, SEM and ex-situ FTIR). The scattering of polychromatic radiation (IR and Ultra violet-visible-near infrared) was used to obtain some information about the powders’ spatial distribution and the evolution of their size distribution. A model, based on the Mie theory and associated with the method of Monte Carlo, was developed to reproduce the optical measurements in-situ. The comparison between experiments and numerical simulations provides new roads in terms of interpretation and analysis of their results. This study is the first step to determine in real-time the dust size and density by coupling the optical measurements with the numerical model based on the Mie theory
Cavarroc, Marjorie. "Nucléation, croissance et comportement de poussières dans les plasmas réactifs radiofréquence basse pression : Des nanocristaux aux grains submicroniques polycristallins". Phd thesis, Orléans, 2007. http://www.theses.fr/2007ORLE2029.
Texto completo da fonteTurco, Francesca. "Etudes des plasmas non-inductifs par injection d'ondes à la fréquence cyclotronique électronique dans le tokamak Tore Supra". Aix-Marseille 1, 2008. http://www.theses.fr/2008AIX11027.
Texto completo da fonteIn this work we addressed the issue of the phenomena typical of the non-inductive discharges in the Tore Supra tokamak, probed by means of localised perturbations of the current density profile, performed by electron cyclotron (EC) waves. Concerning the MHD regimes (which strongly degrade the confinement), we have shown that a dynamic evolution of the safety factor q which tends to shrink its profile appears to be the cause of the triggering of such regimes. The phenomenon of non-linear temperature oscillations (deriving from the non-linear coupling between the electron temperature and the current density) has also been addressed, to provide an analytical description as well as from the experimental point of view. Finally, observations based on an extended database allowed to document the existence of a tight relation between the central value of q passing through low order rational values and the formation of an internal transport barrier (ITB)
Kaeppelin, Vincent. "Caractérisation d'une source de plasma hélicon et application à l'implantation ionique par immersion plasma". Aix-Marseille 1, 2002. http://www.theses.fr/2002AIX11027.
Texto completo da fonteSoulier, Manon. "Caractérisation et optimisation d'une source plasma pour le traitement de semences dans le domaine agroalimentaire". Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30278.
Texto completo da fonteAgri-food industry issues concern food products storage, and yields increase. Since the 1950's, intensive agriculture, chemical pesticides based, and massive irrigation are means used to confront increasing population needs. However, these practices have shown adverse effects on biodiversity and farmers health. Several studies have shown relevant results on cold plasmas fungicidal properties, action on seed germination and on chemicals degradation. A low-pressure air plasma (1 pascal) process was used and optimized for seed treatment. Seeds were placed onto a grounded grid inside an 80 liters reaction chamber exposed to two kinds of plasma. The main source was an electron cyclotron resonance microwave plasma applicator (MW-ECR). Plasma fundamental properties (emitted species, electron densities and temperatures) were measured to map the discharge. This characterization allowed to define two plasma regimes considering the injected power. High species density was generated inside the ECR area. At low-powers, species were diffused inside the plasma volume whereas by exceeding 100 W, they were carried towards the walls. The secondary source was a capacitively coupled radiofrequency plasma source (RF-CCP). The previous plasma parametric study was completed by varying the radiofrequency power. RF power greater than MW power results in higher reactive species density and a volume uniformization of plasma. These species are likely to interact with the seeds. This process efficiency in the agricultural issues of fungal contamination and seed yield optimization was established through two separate studies carried out on seeds which have been certified chemical treatment free. - Seeds represent the first step of the food production chain, constituting most of food products. Fungal contaminants have negative effects on seeds from field to consumer. They are crops spoilers, impacting production yields and food stocks. Molds, such as Fusarium spp. may produce mycotoxins during their metabolism process, responsible on health hazards (e.g. deoxynivalenol: DON or vomitoxin). Plasma discharges fungicidal properties were evaluated on bread wheat seeds (Triticum aestivum L.). Wheat seeds native fungal flora was identified before quantifying their inactivation by the plasma process. The microwave plasma process can face to the substrate matrix effect. This phenomenon was studied by comparing DON degradation onto plate glass carriers and wheat carriers. Post-treated seeds conformity for bread making was evaluated by physicochemical properties such as moisture and gluten contents. Germination yields were also evaluated in order to be consistent with a sustainable agriculture approach. [...]
Chouli, Billal. "Effet des particules rapides sur la rotation des plasmas de Tokamak sans injection de moment angulaire extérieur". Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4084/document.
Texto completo da fonteToroidal flows are found to improve the performance of the magnetic confinement devices with increase of the plasma stability and confinement. In ITER or future reactors, the torque from NBI should be less important than in present-day tokamaks. Consequently, it is of interest to study other intrinsic mechanisms that can give rise to plasma rotation in order to predict the rotation profile in experiments. Intriguing observations of plasmas rotation have been made in radio frequency (RF) heated plasmas with little or no external momentum injection. Toroidal rotation in both the direction of the plasma current (co-current) and in the opposite direction (counter-current) has been observed depending on the heating schemes and plasma performance. In Tore Supra, most observations in L-mode plasmas have been in the counter-current direction. However, in this thesis, we show that in lower hybrid current drive (LHCD), the core toroidal rotation increment is in co- or counter-current direction depending on the plasma current amplitude. At low plasma current the rotation change is in the co-current direction while at high plasma current, the change is in the counter-current direction. In both low and high plasma current cases, rotation increments are found to increase linearly with the injected LH power. Several mechanisms in competition which can induce co- or counter-current rotation in Tore Supra LHCD plasmas are investigated and typical order of magnitude are discussed in this thesis
D'Amico, Ciro. "Filamentation femtoseconde dans les milieux transparents passifs et amplificateurs, et étude de la filamentation comme source de radiation secondaire". Phd thesis, Ecole Polytechnique X, 2007. http://pastel.archives-ouvertes.fr/pastel-00003498.
Texto completo da fonteCollette, Stephanie. "Étude de la réactivité de l’eau dans la torche radiofréquencée et la décharge à barrière diélectrique à l’interface plasma atmosphérique - polyéthylène basse densité". Doctoral thesis, Universite Libre de Bruxelles, 2017. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/256608.
Texto completo da fonteDoctorat en Sciences
info:eu-repo/semantics/nonPublished
Fechner, Benjamin. "Optimisation des antennes radio-fréquences A2 pour le chauffage cyclotronique ionique sur le tokamak JET". Aix-Marseille 1, 1996. http://www.theses.fr/1996AIX11053.
Texto completo da fonteTixier, Christelle. "Dépôt chimique en phase vapeur de carbone amorphe hydrogéné sur des substrats métalliques (TA6V) dans une post-décharge micro-onde assistée par polarisation radio fréquence". Limoges, 1995. http://www.theses.fr/1995LIMO0043.
Texto completo da fonteManaa, Chadlia. "Influence du désordre sur les propriétés opto-électroniques de films minces de cyclohexane déposés par polymérisation plasma". Electronic Thesis or Diss., Amiens, 2015. http://www.theses.fr/2015AMIE0001.
Texto completo da fonteIn this work we have shown the influence of the radio frequency (RF) power on the microstructural, optical, electrical, electronic and morphological properties of thin films polymerized by capacitive PECVD using cyclohexane as precursor gas.At low RF power, the surfaces of our films are porous and highly hydrogenated. They have a hydrophilic character. The increase in the RF power (above 120 W) generates less hydrogenated microstructure and promotes atomic rearrangements between the carbon atoms, including the formation of C = C (C-sp²) bonds. In this RF power range we observed an increase of the conductor character of our polymerized films. These results are in good agreement with optical measurements, show that high RF power induces harder deposited films (increase of n with RF power) and a decrease in the optical gap. This decrease in the optical gap was interpreted in terms of distortions, graphitization and reorganization of the C-sp2 sites, which form larger and better organized clusters. It appears, by combining these measurements with those obtained on the microstructure (Raman and FTIR), that the increase in the electrical conductivity and the decrease of the optical gap is associated with the increase in the number of C = C double bonds, that is to say a "graphitization" of the film, promoting the conductive nature.However, the electrical conductivity values are still a little low, which is explained by the electron paramagnetic resonance (EPR) measurements, which showed the presence of defects within the C-sp2 sites, and that the spin density increases with RF power, suggesting an increase in the defect density in the thin films deposited at high RF power. Furthermore, the narrowing of the EPR lines when the RF power increases indicates a decrease in the exchange interaction between spins as a result of delocalization phenomena in the bond structures
Manaa, Chadlia. "Influence du désordre sur les propriétés opto-électroniques de films minces de cyclohexane déposés par polymérisation plasma". Thesis, Amiens, 2015. http://www.theses.fr/2015AMIE0001/document.
Texto completo da fonteIn this work we have shown the influence of the radio frequency (RF) power on the microstructural, optical, electrical, electronic and morphological properties of thin films polymerized by capacitive PECVD using cyclohexane as precursor gas.At low RF power, the surfaces of our films are porous and highly hydrogenated. They have a hydrophilic character. The increase in the RF power (above 120 W) generates less hydrogenated microstructure and promotes atomic rearrangements between the carbon atoms, including the formation of C = C (C-sp²) bonds. In this RF power range we observed an increase of the conductor character of our polymerized films. These results are in good agreement with optical measurements, show that high RF power induces harder deposited films (increase of n with RF power) and a decrease in the optical gap. This decrease in the optical gap was interpreted in terms of distortions, graphitization and reorganization of the C-sp2 sites, which form larger and better organized clusters. It appears, by combining these measurements with those obtained on the microstructure (Raman and FTIR), that the increase in the electrical conductivity and the decrease of the optical gap is associated with the increase in the number of C = C double bonds, that is to say a "graphitization" of the film, promoting the conductive nature.However, the electrical conductivity values are still a little low, which is explained by the electron paramagnetic resonance (EPR) measurements, which showed the presence of defects within the C-sp2 sites, and that the spin density increases with RF power, suggesting an increase in the defect density in the thin films deposited at high RF power. Furthermore, the narrowing of the EPR lines when the RF power increases indicates a decrease in the exchange interaction between spins as a result of delocalization phenomena in the bond structures
Berio, Stéphan. "Développement de coupleurs à la fréquence hybride pour la génération non inductive du courant dans un Tokamak". Aix-Marseille 3, 1996. http://www.theses.fr/1996AIX30084.
Texto completo da fonteBazinette, Rémy. "Effet de la forme d'excitation électrique sur une décharge contrôlée par barrière diélectrique (dbd) à la pression atmosphérique et application au dépôt de couche mince". Thesis, Pau, 2016. http://www.theses.fr/2016PAUU3009/document.
Texto completo da fonteThe 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
Benhadjala, Warda. "Fiabilité et miniaturisation des condensateurs pour l'aéronautique : de l'évaluation de composants céramique de puissance à l'étude de nanoparticules hybrides céramique / polymère pour technologies enterrées". Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR15271/document.
Texto completo da fonteThe improvement of electronic systems for the deployment of all-electric aircrafts depends on the ability of passive components, such as capacitors, to reduce their volume, weight and cost, and to increase their performance and reliability, particularly in the aeronautical environment. In this context, the objective of this thesis was to study and develop novel capacitor technologies for avionics. In the first part of this work, the evaluation of power ceramic capacitors has been discussed. Indeed, the ceramic technology appeared to be one of the few mature solutions meeting the requirements of OEMs. The characterization, the failure mode, effects and criticality analysis (FMECA) and reliability and robustness assessment of commercial components using original architectures (multi-chip capacitors) have been performed. These results have been completed by a more advanced study on the characterization of new ceramics sintered by spark plasma sintering (SPS). The colossal permittivity of these materials could allow to increase reliability and miniaturization of capacitors while maintaining high values of capacitance and voltage rating. The second part, more fundamental, is devoted to the development of core-shell ceramic/polymer nanoparticles for embedded capacitors operating at radiofrequencies. The synthesis and the physicochemical characterization of the nanocomposites as well as the manufacturing processes of the thick film capacitors are first described. A new broadband electrical characterization methodology has been developed to analyze the dielectric properties and the conduction mechanisms of the nanoparticles. The effects of the temperature and the manufacturing process on the device performance have been investigated. In addition, the durability was evaluated
Urbanczyk, Guillaume. "Interaction of High-Power waves with the plasma periphery of WEST & EAST tokamaks". Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0181.
Texto completo da fonteThis thesis aims at studying phenomena by which Ion Cyclotron Resonance Heating (ICRH) induces interactions between the plasma and the walls of tokamaks, the plasma-metal interactions being deleterious not only to prevent vessel materials degradation but also not to affect plasma performance due to the presence of heavy metallic impurity compared to foreseen fuel (namely deuterium and tritium). This problematic basically affects any machine aiming at heating the ions with waves at the ion cyclotron frequency, which in particular will be the case of ITER. This thesis is the result of a collaboration between CEA Cadarache (France) and the Institute of Plasma Physics in Hefei (China). Various experimental work have been carried out on the EAST (China) and WEST (France) tokamaks in order to identify the relevant parameters allowing to optimize the efficiency by which the ICRF waves – used to heat the plasma – must be excited in order to maximize the amount of power coupled, while simultaneously minimizing the plasma interactions with the walls due to this type of waves and the so called radiofrequency sheath excitation
Nguyen, Anh Phuong. "Interconnexions Through Silicon Via pour applications à Haute fiabilité". Caen, 2016. http://www.theses.fr/2016CAEN2059.
Texto completo da fonteThis thesis focuses on the reliability of the isolation oxide used in 3D interconnections called Through Silicon Via (TSV) developed by IPDIA. This layer is intended to isolate electrically the substrate from the central metallic conductor in the TSV. The isolation oxide SiO2 is obtained by Plasma-Enhanced Chemical Vapor Deposition (PECVD) at low temperature (~200 °C) with Tetraethyl Orthosilicate (TEOS) as the main gas precursor. Through a number of characterizations, it is shown that H+ mobile ions are present in the isolation oxide, due to its low deposition temperature. These ions can move freely within the oxide under the effect of temperature and electric field, modifying the oxide characteristics (the charge topology, the breakdown voltage and the life span) and the substrate resistivity. The impact of these mobile ions is evaluated in the DC domain, via MIS (Métal-isolant-silicium) capacitors, and the RF domain, via CPW (Coplanar Wave Guide) transmission lines, both for simplified planar systems, as well as for the full TSV. Moreover, once the oxide is submitted to annealing at high thermal budget, the present impurities may diffuse into the substrate, creating shallow energy levels within the silicon band gap. As a result, the substrate resistivity decreases drastically involving high losses within the silicon. Two analytical models, allowing to model the diffusion of the mobile species at low/high thermal budget, were developed. These results can be used to evaluate the impact of typical defects of the low temperature isolation oxide for different possible applications of TSVs
Younis, Georges. "Modélisation électrique des décharges RF dans des mélanges N2O/He pour applications aux dépôts PECVD utilisés en micro-électronique". Toulouse 3, 2005. http://www.theses.fr/2005TOU30145.
Texto completo da fonteThis work of thesis is dedicated to the modelling of the electric and energetic behaviour of RF discharges at low pressure and temperature, in the N2O/He mixtures, under different voltages and pressures. A particle model based on the Monte Carlo technique coupled to the Poisson equation is developed to reach this target. Among the results of this model, one can mention, among others, the dissipated power, the electric field and potential, the distribution functions, the reaction coefficients and reaction rates, the deposited energy, the parameters of reaction and transport as well as the densities of the charged particles. In the pure N2O as in the N2O/He mixture, the roles of the different collisional process, on the equilibrium and the maintenance of the discharge, have been highlighted. We showed that the N2O/He discharge, at least until 85% of helium, behave as the one of the pure N2O but with electronic and ionic average energies that increase with the percentage of helium. The energetic study of the discharge is made with the help of a new technique of power calculation, based on the counting of the energies deposited in the medium after every collisional process