Дисертації з теми "Electrical discharge plasma"
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Kang, Jungwon 1967. "The particle trap and plasma parameter studies in an RF argon discharge." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/288834.
Повний текст джерелаBurnette, David Dean. "Nitric Oxide Studies in Low Temperature Plasmas Generated with a Nanosecond Pulse Sphere Gap Electrical Discharge." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1388746668.
Повний текст джерелаOzkan, Alp. "CO2 splitting in a dielectric barrier discharge plasma: understanding of physical and chemical aspects." Doctoral thesis, Universite Libre de Bruxelles, 2016. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/239300.
Повний текст джерелаCarbon dioxide appears as one of the most problematic gases for the environment, mostly because it is responsible for global warming. This is why its increasing concentration into the atmosphere, mainly due to anthropogenic activities, is a real concern for planet Earth. In order to prevent the release of large amounts of CO2, its conversion into value-added products is of great interest. In this context, plasma-based treatments using dielectric barrier discharges (DBDs) are nowadays more and more used for the conversion of this gas. In this thesis, we investigated the CO2 splitting process into CO and O2 via a flowing cylindrical DBD and we studied its conversion and energy efficiency by means of several diagnostic methods, such as mass spectrometry to determine the conversion and energy efficiency of the process, optical emission spectroscopy for gas temperature measurements, and an oscilloscope for electrical characterization, in order to obtain a better understanding of the CO2 discharge itself.First, we focused on an extensive experimental study of a pure CO2 plasma where different parameters were varied, such as the gas residence time, the operating frequency, the applied power, the pulsation of the AC signal, the thickness and the nature of the dielectric. CO2 discharges typically exhibit a filamentary behavior, consisting of many microdischarges, which act as the main source of reactivity in a DBD. A detailed insight in the physical aspects was achieved by means of an in-depth electrical characterization, allowing more insight in the electrical properties of the discharge and more specifically in the microdischarges, which are spread out throughout the active zone of the plasma. It was found throughout this work that the plasma voltage, which reflects the electric field and thus determines how the charged particles are accelerated, the plasma current, which reflects the electron density, but also the number of microdischarges and their average lifetime, play an important role in the efficiency of the CO2 dissociation process. It was revealed that the microdischarge number is important as it represents the repartition of the locations of reactivity. Indeed, as the microfilaments are more spread out in the same discharge volume, the probability for the CO2 molecules to pass through the reactor and interact with at least one microdischarge filament becomes more important at a larger number of microfilaments.The second part of the thesis was dedicated to discharges combining CO2 and H2O or CH4, both being hydrogen source molecules. The combined CO2/H2O or CO2/CH4 conversion allows forming value-added products like syngas (CO and H2), but also hydrocarbons (C2H6, C2H4, C2H2 and CH2O), at least in the presence of methane. Throughout this study, we tried to obtain a better knowledge of the chemistry and physic behind these conversion processes.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Bubelnik, Matthew. "THE EFFECTS OF ELECTRODE GEOMETRY ON CURRENT PULSE CAUSED BY ELECTRICAL DISCHARGE OVER AN ULTRA-FAST LASER FILAMENT." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3695.
Повний текст джерелаM.S.
Other
Optics and Photonics
Optics
Layly, Jean-Baptiste. "Electric contacts subject to high currents : Fundamental processes and application to the interaction between lightning and aeronautic structures." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLX013/document.
Повний текст джерелаLightning is a natural hazardous event that strikes a civil aircraft on average once per 1500 hours of flight. The corresponding high and impulsive currents that may flow along the structure of the aircraft can generate physical constraints with major consequences regarding safety. In particular, when a fastened assembly is crossed by a lightning current, important electric fields and Joule power densities may give birth to a variety of discharge phenomena. The sparking risk is particularly critical in fuel tanks, and different lightning protection technologies and certification procedures are employed to face it. The ignition of discharges is believed to be mostly due to the local electrical resistance at the interfaces between the parts of the assemblies. The aim of this thesis was to model to phenomena that occur at a microscopic scale of such contact resistances subject to high and impulsive currents
Efimova, Varvara, Volker Hoffmann, and Jürgen Eckert. "Electrical properties of the µs pulsed glow discharge in a Grimm-type source: comparison of dc and rf modes." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-138728.
Повний текст джерелаDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
Efimova, Varvara, Volker Hoffmann, and Jürgen Eckert. "Electrical properties of the µs pulsed glow discharge in a Grimm-type source: comparison of dc and rf modes." Royal Society of Chemistry, 2011. https://tud.qucosa.de/id/qucosa%3A27775.
Повний текст джерелаDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
Jinno, Masafumi. "Triggering and Guiding Electrical Discharge, and Plasma Formation by Superposition of Laser Beams - A Fundamental Study on the Controlled Inducing of Lightning -." Kyoto University, 1997. http://hdl.handle.net/2433/154676.
Повний текст джерелаKyoto University (京都大学)
0048
新制・課程博士
博士(工学)
甲第6962号
工博第1645号
新制||工||1083(附属図書館)
UT51-97-L183
京都大学大学院工学研究科電気工学専攻
(主査)教授 橘 邦英, 教授 宅間 董, 教授 藤田 茂夫
学位規則第4条第1項該当
Penkal, Bryan James. "Steps in the Development of a Full Particle-in-Cell, Monte Carlo Simulation of the Plasma in the Discharge Chamber of an Ion Engine." Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1367586856.
Повний текст джерелаMokhtari, Ahmed. "Etude et realisation d'un plasma dense quasi-stationnaire et homogene de 1m de long en presence d'un champ magnetique module spatialement." Paris 6, 1988. http://www.theses.fr/1988PA066423.
Повний текст джерелаMathon, Rémi. "Décharge à Barrières Diélectriques à pression atmosphérique pour la charge bipolaire d’aérosol." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS261/document.
Повний текст джерелаThe measurement of the size distribution of an aerosol (solid or liquid particles in suspension in agas) by electrical mobility analyses requires the neutralization of the aerosol. Neutralization consistsin imparting a charge distribution with a mean charge of 0 by the diffusion of bipolar ions on aerosol.We prove the feasibility of a post- Dielectric Barrier Discharge (DBD) bipolar charger as an alternativeto radioactive neutralizer subjected to legislative constraints. The electrical characterization of awire-to-wire DBD versus the gap, the voltage and the flow-rate highlights 3 kinds of selforganizationsof filaments versus voltage. Moreover, discharge current which represents the chargedspecies production per unit of time is evaluated. In the chosen geometry and operating conditions, apost-discharge ions flux measurement method was developed. We confirm that anelectro-hydrodynamic competition controls the extraction of ions from the gap. In fact, electric fieldsand transit time control positive and negative ions densities and the ratio between them which arecritical for aerosol charging. For the post-DBD charger, ions densities decrease in the charging zone.However, this decrease does not affect the aerosol charge distribution for each particle size withconcentration. In these conditions, the post-radioactive neutralizer and post-DBD neutralizer aerosolsize measurements are compared in order to prove that the post-DBD neutralizer is available forsubmicronic aerosols sizing
Motta, Claudio Costa. "Modelo auto-consistente para a cinética da descarga do laser a vapor de cobre." Universidade de São Paulo, 1996. http://www.teses.usp.br/teses/disponiveis/43/43133/tde-24022014-104827/.
Повний текст джерелаA self-consistent computational model was developed to describe the electrical discharge in a cold plasma, weakly ionized, of the kind usually produced in discharge tubes. The various properties of the species of the plasma as temperature of the electrons, its densities and fluxes could then be obtained. In particular, the model explicitly considers the plasma containing different species in different state of electronic excitation. From these quantities, one can determine the dynamics of the populations involved in the copper atomic laser transition, in a self-consistent model for lasers operation in high repetition rates (-5KHz). The most complete model developed takes into account five level for the buffer gas and nine levels for the copper atom. The copper laser shows two transitions, one in the green and other in the yellow, (5106 Å e 5782 Å), both ending in metaestable states of long duration (~270 µs), in the free atom. In the most complete case studied, thirty processes were considered in the calculations of the plasma dynamics. The formalism first considers solely the temporal dependence and it was used to study the plasma formed by three species: pure He; He and Cu; and Ne and Cu, the last one been currently used in copper vapor lasers. The time dependent populations of the electrons temperature, atoms temperature and densities, in particular the excited levels involved in the laser transitions, could be determined and the results were compared with experimental and simulated results of literature, showing a general good agreement. It was verified, in this model, that the main deexcitation mechanism of the lower metastable laser level is superelastic collisions and not deexcitation via interactions with the walls (diffusion). Therefore, the model was extended to take into account the radial dependence of the plasma in a cylindrical symmetry (radial model). In this case, the skin penetration effect of the electrical field was explicitly considered and the model can then be applied to either small and large diameters, as the diameter is a fundamental parameter for obtaining high power lasers. It is shown that this effect produces a temporally distinct population distribution in the levels of the laser transitions (yellow and green) of the copper atoms, that start in the border and goes to the center, in agreement with the literature. Therefore, the laser pulse starts with the green emission in the border, according to the prediction of our model. It was also found that there is a limit for the maximum length of the laser tube due to the existence of a time window for the positive gain of the laser (~100 ns).
George, Jonathan Alan. "Development of a Plasma Arc Manufacturing Process and Machine to Create Metal Oxide Particles in Water From Wire Feedstock." Diss., CLICK HERE for online access, 2010. http://contentdm.lib.byu.edu/ETD/image/etd3494.pdf.
Повний текст джерелаTawidian, Hagop-Jack. "Formation et comportement de nanoparticules dans un plasma : instabilités dans les plasmas poudreux." Thesis, Orléans, 2013. http://www.theses.fr/2013ORLE2033/document.
Повний текст джерелаThe objective of this thesis is to study the formation of carbonaceous nanoparticles in a low pressure plasma. Dust particles are created by sputtering a polymer layer deposited on the bottom electrode of a capacitively coupled radio-frequency discharge. The presence of dust particles disturbs and changes the plasma properties. The growth of dust particles can trigger low frequency instabilities that evolve with the dust particle size and density. In the center of the discharge, the void, a dust-free region, is observed. It is characterized by an enhanced luminosity. Different diagnostics (electrical measurements, high speed imaging, Laser Induced Fluorescence) are used in order to understand these different behaviors resulting from plasma-dust particle interactions. Dust particle growth instabilities are investigated showing the existence of different instability regimes. Their main characteristics are extracted such as their duration and their evolution frequency. These instabilities are characterized by the formation of small plasma spheroids moving and interacting in the discharge. Several interesting phenomena are evidenced such as the merging and splitting of these plasma spheroids. Concerning the void, our investigations confirmed the high excitation occurring in this region. In the last part of the thesis, the dissociation of aluminium triisopropoxide (ATI) is studied in a plasma using Fourier Transform InfraRed spectroscopy. Thanks to this diagnostic, the evolution of ATI density has been studied as a function of the discharge parameters. We have also quantified the different hydrocarbon compounds formed by polymerization
Hardy, Pierrick. "Etude et qualification aérothermodynamique et électrique d'un actionneur plasma de type jet." Thesis, Toulouse, ISAE, 2012. http://www.theses.fr/2012ESAE0014/document.
Повний текст джерелаImprovement of aerodynamics and environmental performances is a major issue for terrestrial and aeronautical industry.For fulfilling increasing demand, one of the answers is flow control. To achieve flow control, high performance actuators are needed. An innovative technique called Plasma Synthetic Jet actuator consists on applying an electrical discharge in asmall cavity. Plasma is created and increases gas temperature and pressure which results on the creation of a micro-jet through cavity opening.The PhD objectives are to develop the PSJ actuator, to describe actuator mechanisms and to apply it for controlling noise of a high subsonic jet. The first part of the study consists on defining flow control needs and on developing a PSJ actuator prototype. Then,actuator performances are characterised using electrical measurements of the discharge and using aerodynamic measurements. These measurements show that an electrical model of the discharge is needed. Based on the Braginskii model, a simple model is carried out and is applied to the actuator. Efficiency of the PSJ is deduced.The modified Braginskii model is then coupled with an URANS model to achieve frequency modelling of the actuator. Results match aerodynamics measurements .PSJ actuators are applied for controlling jet noise in a second part of the study. Schlieren visualisations are used to show micro-jet interaction with the main jet. Acoustic measurements are then performed and show that the PSJ is a goodactuator to control high subsonic jet noise
Choi, Woong-Sik. "Flame stabilization by a plasma driven radical jet in a high speed flow." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29780.
Повний текст джерелаCommittee Chair: Zinn, Ben; Committee Co-Chair: Jagoda, Jeff; Committee Member: Glezer, Ari; Committee Member: Jeter, Sheldon; Committee Member: Neumeier, Yedidia. Part of the SMARTech Electronic Thesis and Dissertation Collection.
Adámková, Barbora. "Diagnostika plazmatu generovaného ve směsích vody a alkoholů." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2020. http://www.nusl.cz/ntk/nusl-414082.
Повний текст джерелаPoolcharuansin, Phitsanu. "The development of electrical plasma diagnostics for HiPIMS discharges." Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/7495/.
Повний текст джерелаOUAJJI, HASSAN. "Etude de proprietes de transport d'un plasma de melange air-cuivre : modelisation de la colonne d'arc." Clermont-Ferrand 2, 1986. http://www.theses.fr/1986CLF21034.
Повний текст джерелаAksenczuk, Andrzej Marek. "Investigating how the electric discharge properties affect the synthesis and processing of materials by electric discharge assisted mechanical milling." Thesis, School of Mechanical, Materials, and Mechatronic, and Biomedical Engineering, 2016. https://ro.uow.edu.au/theses/4968.
Повний текст джерелаHillborg, Henrik. "Loss and recovery of hydrophobicity of polydimethylsiloxane after exposure to electrical discharges." Doctoral thesis, KTH, Polymer Technology, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3082.
Повний текст джерелаSilicone rubber based on polydimethylsiloxane is used ashigh voltage outdoor insulation, due to its ability to preservethe hydrophobic surface properties during service and evenregain hydrophobicity after exposure to electrical discharges.The underlying processes for the hydrophobic recovery arediffusion of low molar mass siloxanes from the bulk to thesurface and reorientation by conformational changes ofmolecules in the surface region. Only little is known of whichfactors are responsible for the long-term stability of thishydrophobic recovery. It is therefore important to increase theknowledge about the fundamental mechanisms for the loss andrecovery of hydrophobicity of silicone rubbers, exposed toelectrical discharges. Addition-cured polydimethylsiloxanenetworks, with known crosslink densities, were exposed tocorona discharges and air/oxygen-plasma and the loss andrecovery of hydrophobicity was characterised by contact anglemeasurements. The degree of surface oxidation increased withincreasing exposure time with a limiting depth of 100- 150 nm,as assessed by neutron reflectivity measurements. The oxidationrate increased with increasing crosslink density of the polymernetwork, according to X-ray photoelectron spectroscopy. Withinthe oxidised layer, a brittle, silica-like layer was graduallydeveloped with increasing exposure time. The hydrophobicrecovery following the corona or air/oxygen- plasma exposuresoccurred at a slow pace by diffusion of cyclic oligomericdimethylsiloxanes through the micro-porous but uncrackedsilica-like surface layer or at a much higher pace by transportof the oligomers through cracks in the silica-like layer. Theoligomers were present in the bulk, but additional amounts wereformed during exposure to corona discharges. High-temperaturevulcanised silicone rubber specimens were aged in a coastalenvironment under high electrical stress levels (100 V/mm). Thechanges in surface structure and properties were compared tothe data obtained from specimens exposed to coronadischarges/plasma. The dominating degradation mechanism wasthermal depolymerisation, initiated by hot discharges. Thisresulted in the formation of mobile siloxanes, of which the lowmolar mass fraction consisted of cyclic oligomericdimethylsiloxanes. Oxidative crosslinking resulting insilica-like surface layers was not observed during theseconditions.
Keywords:silicone rubber, polydimethylsiloxane,hydrophobicity, corona, air-plasma, oxygen-plasma, surfacecharacterisation, degradation products, crosslink density.
Tihonová, Jitka. "Aplikace elektrického výboje v kapalinách pro čistění nekovových archeologických předmětů." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2020. http://www.nusl.cz/ntk/nusl-414085.
Повний текст джерелаRusterholtz, Diane. "Nanosecond Repetitively Pulsed Discharges in Atmospheric Pressure Air." Phd thesis, Ecole Centrale Paris, 2012. http://tel.archives-ouvertes.fr/tel-00997397.
Повний текст джерелаYuan, Qiulin. "Studies of electric discharges and their interactions with gases." Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/22086.
Повний текст джерелаWendelstorf, Jens. "Ab initio modelling of thermal plasma gas discharges (electric arcs)." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=961148527.
Повний текст джерелаOrel, Inna. "Measurements of electric field and dissociated species in nanosecond discharges for kinetic and biological applications." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX097.
Повний текст джерелаThe present thesis combines work on absolute and time resolved measurements of O and N atom densities and electric field as a function of specific deposited energy in nanosecond pulsed discharges at high reduced electric fields (above 100 Td) that develop in form of fast ionization wave (FIW). Ground state O-atom number density, [O], in capillary discharge in 28 mbar air with specific deposited energy of 0.5-1 eV/molecule was measured by optical actinometry technique with Ar as an actinometric admixture. Ar actinometric signal was corrected for N2 first positive system’s background emission. The experiment was highly supported by modelling of kinetic processes in plasma. It has been revealed that in conditions of both high reduced electric field and high specific deposited energy, reactions between charged and/or excited species become important. In particular, the 3-body recombination of O+ and Ar+ ions with electron as a third body become dominant in the early afterglow. The peak measured [O], 7.5x10^(16) cm^(-3), corresponds to 23% dissociation fraction. Longitudinal electric field was measured by electric field induced second harmonic generation (E-FISH) technique with picosecond laser in tube discharge in 20-100 mbar pure N2 with low specific deposited energy at the level of 10^(-3)-10^(-2) eV/molecule during the propagation of FIW and quasi-steady-state discharge. Despite ns-scale laser jitter, temporal resolution as high as 200 ps was attained with help of developed shot-by-shot data treatment procedure that also performed statistical analysis. The electric field in FIW was shown to have a pressure-independent peak value of about 10 kV/cm and 1-3 ns FWHM that increases with pressure. The peak reduced electric field reaches the value of 2 kTd at 20 mbar. It has been concluded that the second harmonic signal originates from the quartz of the discharge tube which disables the possibility of Laplacian field calibration. The calibration against electric field measured by back current shunt and capacitive probe was applied instead. Ground state N-atom number density, [N], in capillary and tube discharges was measured by two photon absorbed laser induced fluorescence (TALIF) technique. For 1 eV/molecule at capillary discharge, [N] reaches the peak value of 1.3x10^(17) cm^(-3) at about 1 us after the initiation of the discharge. [N] stays at the peak value up to 1 ms and then decreases exponentially until reaches the detection limit at 20 ms. The [N] peak value corresponds to 10% dissociation fraction and to effective N-atom production energy cost of almost 10 atoms/100 eV. Such high efficiency is governed by additional population process between charged and excited species, namely, electron impact dissociation of N2(A,B,C) triplet states. For 10^(-3)-10^(-2) eV/molecule at tube discharge, [N] shows rather constant 5.5x10^(12) cm^(-3) value for up to 80 us and further decreases. The thesis also discusses the interest of ns discharges in biological applications on the example of plasma-assisted regenerative medicine. Cold atmospheric plasma (CAP) device was developed for treatment of dental pulp derived mesenchymal stem cells. CAP effect on cells was assessed by morphological cell analysis, viability test, cytotoxicity test, proliferative test, labelled flow cytometry for measurements of intracellular ROS accumulation and fluorescence microscopy for cytoskeleton and nuclei imaging that had led to establishment of non-toxic protocol of cell treatment by CAP
Troughton, Samuel Christopher. "Phenomena associated with individual discharges during plasma electrolytic oxidation." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/288879.
Повний текст джерелаBless, Frédéric. "Investigation of atmospheric-pressure plasma discharges for thin film deposition." Thesis, University of Liverpool, 2015. http://livrepository.liverpool.ac.uk/2050119/.
Повний текст джерелаBowes, Michael. "Plasma diagnosis of reactive high power impulse magnetron sputtering (HiPIMS) discharges." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/18833/.
Повний текст джерелаAyeleso, Ayokunle Oluwaseun. "An improved plasma energy conversion system for electric power generation." Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2694.
Повний текст джерелаThe generation of electricity through the conventional conversion system such as thermal and hydroelectric plants may no longer be sufficient to meet the increasing demands and usage. One of the major reasons for shortage supply of electric power is due to the lack of fossil fuel and other conventional resources that are currently being used in Africa. In addition, the conversion process of the conventional system often causes pollution which contributes to global warming. Therefore, there is a need for this research to develop novel and alternative methods of generating electric power. Among these methods is the Magnetohydrodynamics (MHD) conversion system, which is a direct energy conversion system. In this system, plasma or ionised gas is directly converted into electric power with generating efficiency of about 62 %. The conversion process of the MHD system is based on the principle of Faraday’s Law of electromagnetism and fluid dynamics. The focus of the present study is to investigate alternative methods through which an MHD power generator can be coupled to the existing thermal plants in South Africa. In doing so, the thermal cycle efficiency of these conventional plants can be improved. Another goal of this study is to investigate the behaviour of an MHD generator prototype under exposure to plasma through simulation and experimentation in a laboratory setting.
Mahalingam, Sudhakar. "Particle Based Plasma Simulation for an Ion Engine Discharge Chamber." Wright State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=wright1198181910.
Повний текст джерелаSözer, Esin Bengisu Kirkici Hulya. "Gaseous discharges and their applications as high power plasma switches." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SPRING/Electrical_and_Computer_Engineering/Thesis/Sozer_Esin_45.pdf.
Повний текст джерелаGomez, S. "Laser induced fluorescence measurements in inductivity coupled of processing plasmas." Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368755.
Повний текст джерелаDebien, Antoine. "Étude électromécanique et optimisation d'actionneurs plasmas à décharge à barrièrediélectrique – Application au contrôle de décollement sur un profil d'aile de type NACA0015." Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2253/document.
Повний текст джерелаThis work is conducted in the framework of the European PlasmAero project that aims to demonstrate how plasma actuators can be used to control aircraft aerodynamic. Surface Dielectric Barrier Discharge (DBD) is an innovative solution to control a flow with the electric wind induced by the electrohydrodynamic (EHD) force produced by a surface discharge. A first part is dedicated to plasma actuators study. The exposed electrode shape of a DBD actuator is investigated by electrical, optical and mechanical characterization. Discharges properties and EHD force evolution is fully dependent of exposed electrode shape. With an optimized active electrode shape, streamer discharge is cancelled while actuator effectiveness is increased from 0.65 to 0.97 mN/W. Flow field induced by multiple electrode design is also investigated. An innovative multi-DBD design is proposed. Inhibition of mutual interaction between successive DBD actuators and exposed electrode shape optimization conduct to an electric wind velocity of 10.5 m/s. In a second part, the control of boundary layer separation on a NACA 0015 airfoil is investigated. An ac DBD, a multi-DBD and a nanosecond DBD are used to manipulate separation at a Reynolds number Re = 1.3μ106, with tripped and natural boundary layer. Results show that actuators can effectively remove the separation existing without actuation
Tmenova, Tetiana. "Étude expérimentale de la décharge électrique pulsée dans l'eau." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30248.
Повний текст джерелаAlthough electric spark dispersion processes have been known for a while, the plasma created during this process is not well-studied and understood. The complexity of the phenomena occurring during the underwater electric discharges brings additional obstacles to experimental characterization of such plasmas imposed by as small sizes of plasma and their often-short duration, difficult environment of the discharge, its stochastic nature and poor reproducibility. The main objective of this thesis was set on the investigation of the plasma occurring during the synthesis of metal colloids by an electrospark dispersion generator. The first success of this work was simply to show the applicability of optical emission spectroscopy diagnostics to such discharges. The efforts made for the development of the effective experimental approach in order to meet this research objective have been well rewarded. The results obtained in this work allow to draw interesting conclusions about the physical properties of the underwater pulsed electric discharge plasma of the considered configuration. Discharge ignites from the short circuit and molten bridge mechanism. Ignition of the arc is characterized by formation of bubble resulting from a pressure shockwave. High-speed imaging allowed to distinguish two phases in the discharge lifetime: plasma in water, and plasma in bubble formed afterwards. From the vapor condensation point of view, these two phases presumably lead to different quenching conditions, and, consequently, to the different synthesis conditions. In the case of discharge generated between molybdenum electrodes, there is a slowly-decaying light emission after the end of the discharge which can be attributed to the ejection of eroded metallic particles. The energy dissipation on the electrodes was found to be different for copper and molybdenum: due to the lower thermal conductivity of molybdenum, smaller portion of energy transferred to the electrodes results in higher energy input into the arc column. Spectroscopic measurements allowed to establish that plasma density (~ 10 17 cm-3) and moderate temperature (0.6 - 0.95 eV) correspond to a pressure greater than 1 bar. Moreover, plasma presents several non-ideal effects, such as broadening and the asymmetrical shape of the Ha line and absence of Hß line. In general, plasma properties were found to be relatively insensitive to most of the discharge parameters, such as the discharge current or the type of liquid with the main differences being associated to the used electrodes material
Karaoglan, Gulten. "Investigation Of Dc Generated Plasmas Using Terahertz Time Domain Spectroscopy." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12612070/index.pdf.
Повний текст джерелаTyl, Clémence. "Study of the memory effect in atmospheric pressure townsend discharges in nitrogen with addition of oxidizing gas : temporally and spatially resolved electrical and optical characterizations." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30296.
Повний текст джерелаPlasma processes at atmospheric pressure using Dielectric Barrier Discharges (DBD) are a good alternative to low pressure non-thermal plasma processes for various applications such as surface treatment, thin-film coating, sterilization etc. Indeed, they can be operated without complex vacuum facilities and allow the treatment of large surfaces that can be implemented directly into assembly lines. However, DBDs are usually filamentary, leading to non-homogeneous depositions on the treated surfaces. In certain condition depending on the experimental parameters (geometry, gas nature, power supply, etc.), a homogeneous discharge can be obtained leading to a uniform surface treatment. Nevertheless, even in the homogeneous mode, the DBDs properties are not necessarily the same at any point on the discharge surface, because of the gas flow circulation in particular, but also in case of materials with a properties gradient, or in case of self-organization phenomena. In order to better characterize the spatial distribution of the discharge, a new local electrical diagnostic tool to measure the local current densities has been developed during this thesis. Indeed, electrical measurements are widely used to characterize the DBDs as they give access to various parameters such as the gas voltage, discharge current, dissipated power etc. However, the measured current is integrated on all the surface of the electrodes. To be able to measure the local currents, the 3×3 cm2 ground electrode from the discharge cell has been divided into 64 segments, and a data acquisition system has been developed in order to simultaneously acquire the 64 measured currents with a high enough sampling rate for the data processing. This new electrical diagnostic tool can be correlated in time and space with optical measurements with an intensified iCCD camera, coupled with optical filters, to obtain information on the densities of some species in the plasma. The aim of this thesis is to better understand to local power dissipation, and to refine the characterization of the involved species in the different discharge regimes, especially to obtain a homogeneous regime. Homogeneous DBDs are ignited by a Townsend breakdown. For a Townsend breakdown to occur, a production source of seed electrons is necessary between two discharges, when the electric field is lower than the breakdown voltage. This breakdown is related to a memory effect from one discharge to the following one, that is visible on the electrical measurements with a discharge current jump. The hypotheses on the memory effect origin can be separated into two categories.[...]
Fojtíková, Nikola. "Diagnostika plazmatu generovaného v atmosféře simulující podmínky na Marsu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-445140.
Повний текст джерелаGoldberg, Benjamin M. "Electric Field Measurements in Non-Equilibrium ElectricDischarge Plasmas Using Picosecond Four-Wave Mixing." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449236861.
Повний текст джерелаWilson, Darren James. "Plasma treatment of polymers for modifying haemocompatibility." Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367214.
Повний текст джерелаJúnior, Adonias Ribeiro Franco. "Obtenção de revestimentos dúplex por nitretação a plasma e PVD-TiN em aços ferramenta AISI D2 e AISI H13." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-02102003-114623/.
Повний текст джерелаIn this work, the influence of both the microstructure and the load-bearing capacity of nitrided layers, formed on top of AISI D2 and AISI H13 tool steels, on adhesion and wear resistance of PVD-TiN coatings was studied. The threshold nitriding potential curves for the above mentioned steels and the optimum conditions of the pre-treatments which increased the adhesion as well as the wear resistance of the PVD-TiN were determined experimentally. By using longer nitriding times (about 11 h) and lower nitrogen contents in the gas mixture (about N2-5%vol.), it was possible to minimize the pile-up degree of the TiN/H13 nitrided substrates and, consequently, the occurrence of coatings chipping. This flaw persists when the nitrided layer is thin, due to an abrupt transition of mechanical properties at the TiN coating / steel core interface. Shorter nitriding times (about 42 min.) and lower nitrogen contents (about N2-5%vol.), on the other hand, are sufficient to guarantee a better adhesion of TiN coatings on AISI D2 tool steel, as the core of such steel possesses relatively better load-bearing capacity than the AISI H13 tool steel. The presence of a black layer at the TiN/nitrided layer interface was observed in all coatings deposited over nitrided layers produced above the threshold nitriding potential curves. This layer affects adversely the wear resistance and the adhesion of the TiN coatings. When higher loads are applied on the coated surface, egg shell type flaws easily occur.
Ronchi, Gilson 1985. "Estudos de descargas de plasma contínuas." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278560.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
Made available in DSpace on 2018-08-19T18:26:47Z (GMT). No. of bitstreams: 1 Ronchi_Gilson_M.pdf: 6202845 bytes, checksum: e9580b7846e57a9eb526cdf45b808564 (MD5) Previous issue date: 2012
Resumo: O conhecimento das condições para ruptura de gases e a formação de plasma são questões importantes, não apenas de interesse fundamental, mas também para muitas aplicações, tais como em deposição de filmes finos de óxido ou polímeros, limpeza de superfície de materiais ou implantação iônica, por exemplo. A ruptura de gases descrita pela lei de Paschen com a teoria de Townsend, na qual a tensão de ruptura é uma função do produto da pressão p do gás pela distância d entre os eletrodos, proporciona uma adequada descrição em certas condições, em gases sob baixa pressão, quando a distância entre os eletrodos é muito menor que o raio R dos mesmos. A medida que a razão desses valores aumenta, as curvas de Paschen são deslocadas para regiões de tensão de ruptura mais elevadas, bem como para valores pd mais elevados. Investigamos aqui, os motivos e as consequências desse fenômeno, bem como uma proposta de lei de escalas capaz de determinar a tensão de ruptura em condições distintas de descargas. Tal lei de escalas obtida empiricamente faz uso, além da pressão e distância dos eletrodos, da razão R/d, que surge naturalmente ao se considerar o processo de difusão na descarga. Discutimos ainda sobre as principais técnicas de diagnósticos aplicáveis ao plasma, para obtenção, por exemplo, das temperaturas e densidades eletrônicas/iônicas. Em particular, revisamos as técnicas de espectroscopia e sonda de Langmuir, que são técnicas importantes amplamente utilizadas
Abstract: The understanding of the gas breakdown mechanism and plasma formation are important issues not only of fundamental interests, but also for many applications such as oxide thin films or polymers deposition, surface cleaning and ion implantation, for example. The breakdown described by Paschen¿s law with Townsend¿s theory, where the breakdown voltage is a function of the product of the gas pressure p and the gap distance d, provides a very accurate description under certain conditions as in low pressure gases when the distance between the electrodes is much smaller than its radius R. As the ratio d/R increases, the Paschen curves are shifted to regions of higher breakdown voltage, as well as higher pd values. In this work we investigate the reasons and consequences of this phenomenon, as well as a scaling law capable of determining the breakdown voltage of discharges in different conditions. This scalling law, obtained empirically, uses the gas pressure, the electrodes gap distance and the ratio R/d, which arises naturally when one consider the diffusion process in the discharge. We also discuss the main diagnostic techniques applicable to plasma to obtain, for example, temperature and electronic/ionic density. In particular, we review the techniques of spectroscopy and Langmuir probe, which are important techniques widely used
Mestrado
Física
Mestre em Física
Němcová, Lucie. "Interakce plazmatu s kapalnou fází." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2013. http://www.nusl.cz/ntk/nusl-233370.
Повний текст джерелаMarcus, Francisco Alberto. "Instabilidade dinâmica das flutuações eletrostáticas em tokamaks." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-02082013-153147/.
Повний текст джерелаIn this work we have studied the transport of particles in a magnetically confined plasma, due to electrostatic drift waves. The adopted model describes the trajectory of the guiding center of a particle in a uniform magnetic field perpendicular to a radial electric field perturbed by drift waves. We have used the Hamiltonian description for the guiding center trajectory. The drift produced by the radial electric field is represented by the integrable part of the Hamiltonian, while the other part contains periodic perturbations representing the fluctuations of the electric field associated to the drift waves. In this way we obtain chaotic orbits that determine the particles radial transport. For several balance conditions, we present the variation of the radial transport of particles with the amplitude of the perturbation. V/e have used the experimental data of the electrostatic turbulence measured in TBR-1 tokamak to verify, the validity of the model and the importance of the drift waves in the particles radial transport. We have also compared the values of the experimental diffusion coefficient with those provided by using the model, obtaining results with the same order of magnitude.
Ongkodjojo, Ong Andojo. "Electrohydrodynamic Microfabricated Ionic Wind Pumps for Electronics Cooling Applications." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1354638816.
Повний текст джерелаRichard, Frédéric. "Etude et caracterisation d'une decharge electrique glissante dans l'air a pression atmospherique." Orléans, 1995. http://www.theses.fr/1995ORLE2061.
Повний текст джерелаAkbar, Demiral Salih. "The Non-uniform Argon Dc Glow Discharge System Parameters Measured With Fast Three Couples Of Double Probe." Phd thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607109/index.pdf.
Повний текст джерела#958
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D) has been investigated. Since, the probe radius is smaller than Debye length, the orbital motion limited (OML) theory has been used. As a result, the electron temperature (at the center) decreased and density increased with decreasing tube radius, and they have maximum values at the first probe (near the cathode). The electron density ne was observed to decrease and electron temperature Te to increase with increasing the discharge current. The floating potential has less negative value with decreasing tube radius except at the higher currents. Finally, it has been found that the &
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is proportional with electron density, but it remains constant depending on the value of Te and ne.
Javidi, Shirvan Alireza. "Modelling of Electric Arc Welding : arc-electrode coupling." Licentiate thesis, Högskolan Väst, Avd för maskinteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-5826.
Повний текст джерелаRoettgen, Andrew M. "Vibrational Energy Distribution, Electron Density and Electron Temperature Behavior in Nanosecond Pulse Discharge Plasmas by Raman and Thomson Scattering." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1428940661.
Повний текст джерелаAndreu, i. Batallé Jordi. "Plasma de silà amb confinament electrostàtic per a la obtenció de silici amorf hidrogenat." Doctoral thesis, Universitat de Barcelona, 1986. http://hdl.handle.net/10803/670243.
Повний текст джерела