<p>In this work a flow stabilized corona torch plasma was used for periodic domain inversion of MgO-doped lithium niobate with 19 .1 μm periodic gratings. The effective non-linear coefficient (derr) achieved through corona discharge poling was 17.5 pm/V, which agrees well with theoretical value of 16~19 pm/V. By analysing the second harmonic generation (SHG) tuning curves, the grating uniformity over the 10 mm grating was investigated. The 0.6 run bandwidth of the SHG tuning at full width half maximum (FWHM) corresponded exactly to the theoretical value. The agreement between experimental data and theoretical results imply that the obtained periodically poled lithium niobate (PPLN) has high quality. By controlling temperature in the range of 20 °C to 120 °C tunability of SHG wavelength was demonstrated between 782 run and 788 run.</p> <p>Discharge characteristics of the corona were studied using a floating potential double probe and optical emission spectroscopy. Using the double probe the distribution of ion density downstream of the corona torch was observed. The maximum ion density of 2 x 1018 (ions/cm3) was achieved 2 mm below the discharge electrode. Measurement of the optical emission spectrum was used to determine the vibrational ion temperature to be 3953 K. The observed spectrum consisted entirely of the second positive band of nitrogen.</p> <p>The applied voltage range of 9 kV to 10 kV was observed to be optimum for domain growth in periodic poling. Poling uniformity of the 12 mm grating was optimized for an electrode to crystal spacing of 13 mm. Increasing the crystal temperature during poling reduces the required coercive field for domain inversion. This reduces the required applied voltage and also reduces the required poling time by increasing the domain-switching rate. Proton exchange pretreatment of the (+z) crystal surface prior to poling has been demonstrated to control domain spreading, however future efforts are required to ensure a more reliable nucleation condition. Both high vacuum and spin coated photoresist function to increase electrical discrimination of anode grating and provide an improved nucleation condition for periodic poling of MgO-doped lithium niobate. Poling uniformity of the 12 mm grating was optimised for an electrode to crystal spacing of 13mm.</p> / Thesis / Master of Applied Science (MASc)

Στα πλαίσια της παρούσας διπλωματικής εργασίας μελετήθηκε, σχεδιάστηκε και κατασκευάστηκε ένα σύστημα ελέγχου ενός φασματοσκοπίου εκπομπής υψηλής φασματικής ανάλυσης. Η συσκευή αυτή, γνωστή και ως μονοχρωμάτορας, χρησιμοποιήθηκε για την καταγραφή φασμάτων εκπομπής από μία εκκένωση αίγλης σε διάκενο ακίδα-πλάκα σε συνθήκες χαμηλής πίεσης και θερμοκρασίας. Ο μονοχρωμάτορας χρησιμοποιεί ένα διάφραγμα περίθλασης που αναλύει μια πολυχρωματική δέσμη που προσπίπτει σε αυτό, στα επιμέρους μήκη κύματος Ο έλεγχος του συνόλου των λειτουργιών του συστήματος καθώς και η καταγραφή των φασμάτων πραγματοποιείται με τη χρήση λογισμικού που αναπτύχθηκε υπό την πλατφόρμα Labview. Στα πλαίσια αυτής της εργασίας υλοποιήθηκε: Η σύνδεση της συσκευής οδήγησης του βηματικού κινητήρα που περιστρέφει το διάφραγμα με κατάλληλο τροφοδοτικό. Η ενίσχυση των σημάτων ελέγχου της συσκευής οδήγησης. Η ενίσχυση και καταγραφή του ρεύματος του φωτοπολλαπλασιαστή που καταγράφει τη φωτεινή δραστηριότητα. Η βαθμονόμηση του μονοχρωμάτορα. Η ανάπτυξη λογισμικού, φιλικού προς τον χρήστη, με το οποίο ελέγχεται ο μονοχρωμάτορας, καταγράφεται το φάσμα και αποθηκεύεται σε αρχείο για περαιτέρω επεξεργασία. Η συγκέντρωση του φωτός που εκπέμπεται από την εκκένωση και η οδήγησή του στην είσοδο του μονοχρωμάτορα με τη χρήση κατάλληλης οπτικής διάταξης. Η καταγραφή φασμάτων του παραγόμενου πλάσματος της εκκένωσης κατά μήκος του διακένου. Η μελέτη και ανάλυση των καταγεγραμμένων φασμάτων. / The main purpose of this thesis was to construct a control system for a high precision spectrometer. Using this spectrometer, also known as monochromator, spectra was recorded from a low temperature – low pressure, pin to plate, glow discharge. The monochromator uses a diffraction grating to separate spatially a polychromatic beam of light available at its input. The stepper motor control, along with the recording of spectra, is being conducted by suitable software developed under the Labview platform. Among the challenges of the thesis was to: Αssemble a stepper motor controller which rotates the diffraction grating with a suitable power supply. Αmplify the control signals of the controller. Αmplify the photomultiplier signals which records the luminous intensity. Calibrate the monochromator. Develop a user-friendly software which can control the monochromator, record spectra and export a file with the recorded spectra for further use. Concentrate the emitted light of the discharge and guide it to the monochromator's input slit, using a UV lens and an optical fiber. Capture emitted spectra of the produced plasma, at different positions along the pin to plate gap. Analyze the recorded spectra.

Made available in DSpace on 2014-12-17T14:06:56Z (GMT). No. of bitstreams: 1 DaniloCB_DISSERT.pdf: 3100682 bytes, checksum: ca6553081fbf48a3fd486b3f20d01cc2 (MD5) Previous issue date: 2011-06-09 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Discs were grade II cp Ti oxynitride by plasma of Ar - N2 - O2 using different proportions of individual gases. These ratios were established from analysis of optical emission spectroscopy (OES) of plasma species. The proportions that resulted in species whose spectra showed an abrupt change of light intensity were chosen for this study. Nanohardness tests revealed that there was a correlation between the intensity of N2 + species with the hardness, because the treatments where they had a higher intensity, obtained a higher value nanohardness, although the crystalline phases have remained unchanged. With respect to topography, it was observed that in general, the surface roughness is related to the intensities of plasma species, because they may have different values depending on the behavior of the species. Images obtained by optical microscopy revealed a surface with grains of different colors to optical reflectance showed a peak of reflection in the red area. Measures the contact angle and surface tension showed hydrophilic properties and hydrophilic with little variation of polar and dispersive components of surface tension / Discos de tit?nio cp grau II foram oxinitretados por plasma de Ar - N2 - O2 usando diferentes propor??es de gases individuais. Essas propor??es foram estabelecidas a partir de an?lises de espectroscopia de emiss?o ?ptica (OES) das esp?cies do plasma. As propor??es que resultaram em espectros cujas esp?cies apresentaram varia??o abrupta de intensidade luminosa foram escolhidas para o presente trabalho. Os ensaios de nanodureza revelaram que houve uma rela??o entre a intensidade da esp?cie N2 + com a dureza, pois para os tratamentos onde estas apresentaram maior intensidade, obteve-se maior valor de nanodureza, embora as fases cristalinas tenham se mantido inalteradas. Com rela??o ?s topografias, observou-se que de um modo geral, a rugosidade superficial est? relacionada com as intensidades das esp?cies do plasma, pois estas podem apresentar valores diferentes dependendo do comportamento das esp?cies. Imagens obtidas por microscopia ?ptica revelaram uma superf?cie com gr?os de diferentes cores e a reflet?ncia ?ptica mostrou um pico m?ximo de reflex?o na regi?o do vermelho. As medidas de ?ngulo de contato e tens?o mostraram superf?cies com propriedades hidrof?licas e pouco hidrof?licas com varia??o das componentes polar e dispersiva da tens?o superficial

Made available in DSpace on 2014-12-17T14:07:10Z (GMT). No. of bitstreams: 1 IgorON_DISSERT.pdf: 2261728 bytes, checksum: ec2c0dd089b3f051427a0e42ea972424 (MD5) Previous issue date: 2011-12-09 / The technique of surface coating using magnetron sputtering is one of the most widely used in the surface engineering, for its versatility in obtaining different films as well as in the micro / nanometric thickness control. Among the various process parameters, those related to the active species of the plasma are of the most fundamental importance in the mechanism and kinetics of deposition. In order to identify the active species of the plasma, parameters such as gas flow, pressure and density of electric power were varied during titanium coating on glass substrate. By flowing argon gas of 10, 20, 30, 40 and 50 sccm (cubic centimeters per minute) for each gas flow a sequential scan of the electric current of 0.10, 0.20, 0.30, 0.40 , 0.50 A. The maximum value of 0.50 A was chosen based both on literature data and on limitations of the equipment. The monitoring of plasma species present during the deposition was carried out in situ by the technique of optical emission spectroscopy (OES) through the spectrometer Ocean Optics USB2000 Series. For this purpose, an apparatus was developed to adapt the OES inside the plasma reactor to stay positioned closest to the target. The radiations emitted by the species were detected by an optical fiber placed behind the glass substrate and their intensities as a function of wavelength were, displayed on a monitor screen. The acquisition time for each condition of the plain parameters was related to the minima of spectral lines intensities due to the film formed on the substrate. The intensities of different emission lines of argon and titanium were then analyzed as a function of time, to determine the active species and estimate the thickness of the deposited films. After the deposition, the coated glasses thin films were characterized by optical transmittance through an infrared laser. It was found that the thickness and deposition rate determined by in situ analysis were consistent with the results obtained by laser transmittance / t?cnica de revestimento superficial utilizando magnetron sputtering ? uma das mais utilizadas pela engenharia de superf?cie, pela sua versatilidade na obten??o de diferentes filmes bem como no controle micro/nanom?trico de sua espessura. Dentre os v?rios par?metros do processo, aqueles relacionados com as esp?cies ativas do plasma s?o de fundamental import?ncia no mecanismo e cin?tica da deposi??o. Com o objetivo de identificar as esp?cies ativas do plasma, par?metros como fluxo de g?s, press?o de trabalho e densidade de pot?ncia el?trica foram variados durante o revestimento de tit?nio em substrato de vidro. Foi utilizado arg?nio com fluxos de 10; 20; 30; 40 e 50 sccm (cent?metro c?bico por minuto) e para cada fluxo de g?s uma varredura sequencial da corrente el?trica de 0,10; 0,20; 0,30; 0,40; 0,50A (amp?res). O valor de m?ximo de 0,50A foi escolhido com base em dados da literatura e limita??es do equipamento. O monitoramento das esp?cies do plasma presentes durante a deposi??o foi realizado "in situ", pela t?cnica de espectroscopia de emiss?o ?ptica (EEO) atrav?s do espectr?metro USB2000 Series da Ocean Optics. Para isso um aparato foi desenvolvido para adaptar o EEO dentro do reator de plasma de maneira que ficasse posicionado o mais pr?ximo poss?vel do alvo. As radia??es emitidas pelas esp?cies foram detectadas atrav?s de uma fibra ?ptica colocada por tr?s do substrato de vidro e suas intensidades, em fun??o do comprimento de onda, foram exibidas na tela de um monitor. O tempo de aquisi??o para cada condi??o de par?metro do plasma foi aquele em que a intensidade espectral deca?a para zero, devido ao filme formado no substrato. As intensidades de diferentes linhas de emiss?o de arg?nio e de tit?nio foram ent?o analisadas em fun??o do tempo, para determinar as esp?cies ativas e estimar a espessura dos filmes depositados. Ap?s a deposi??o, os filmes finos que revestiram os vidros foram caracterizados por transmit?ncia optica, atrav?s de um laser no infravermelho. Verificou-se que os valores da espessura e da taxa de deposi??o s?o determinada pela an?lise "in situ", foram coerentes com os resultados obtidos atraves da transmit?ncia por laser

Les décharges plasma dans la vapeur d’eau sont d’un grand intérêt pour de nombreuses applications potentielles, telles que le traitement biomédical, la production d’hydrogène ou la combustion assistée par plasma. Cette thèse propose une caractérisation expérimentale détaillée de l’effet thermique et chimique des décharges non-thermique nanosecondes répétitives pulsées (NRP) à la pression atmosphérique dans la vapeur d’eau pure. Un réacteur a été conçu pour fonctionner avec la vapeur d’eau préchauffée à 400-500 K. Les conditions opératoires retenues sont un débit de 300 g/h à 500 K et une décharge avec une énergie moyenne de 20 à 100 W, en régime Spark. Différents diagnostics ont été développés afin de déterminer les produits de cette décharge en termes d’espèces intermédiaires, de densité électronique et des produits stables. La concentration des produits de réaction stables (H2 et O2) et leurs débits respectifs ont été mesurés par chromatographie en phase gazeuse. Une valeur maximale de 0,85 g-H2/kWh a été obtenue. La densité électronique a été mesurée par spectroscopie d’émission optique (OES) résolue en temps grâce à l’élargissement par effet Stark des raies (H, H et O). La densité électronique maximale mesurée est 2X1018 cm-3 pendant l’impulsion. La température du gaz a été mesurée lors de la décharge de 20 ns par OES ainsi que entre deux décharges (100 us) par fluorescence induite par laser du radical OH (OH-PLIF) à deux couleurs. L’élévation maximale de la température est de 950 K après l’impulsion, et la température décroît ensuite de façon exponentielle avec un temps de décroissance caractéristique de 5 us. La densité relative du radical OH a été mesurée par OH-PLIF, révélant la durée de vie relativement longue de OH avec un temps de décroissance d’environ 50 us. En utilisant un modèle cinétique 0-D, la densité absolue OH à la fin de l’impulsion a été estimée à 400 plus ou moins 200 ppm. Les résultats obtenus ont permis d’éclairer les mécanismes sous-jacents à la génération de décharges NRP en régime Spark dans la vapeur d’eau pure à basse température. / Plasma discharges in water vapor are of great interest for a variety of potential applications, such as biomedical treatment, hydrogen production, or plasma assisted combustion. This thesis proposes a detailed experimental characterization of the thermal and chemical effects of non thermal discharge, particularly Nanosecond Repetitively Pulsed (NRP) discharges at atmospheric pressure in pure water vapor. A reactor has been designed to operate with water vapor preheated at 400-500 K. We investigated the various discharge regimes and the operating conditions for each regime. The selected operating conditions are a flow rate of 300 g/h at 500 K. The discharge has an average energy from 20 to 100 W in the spark regime. Various diagnostics have been developed in order to infer the products of this discharge in terms of intermediate species, electrons, and stable products. The concentration of the reaction products (H2 and O2) and their respective flow rates were measured using gas chromatography. A maximal value of 0.85 g- H2/kWh was obtained. The electron number density has been measured using time-resolved optical emission spectroscopy (OES) via Stark-broadened lines (H, H and O). The maximum measured electron density is 2X1018 cm-3 during the pulse, and a slow recombination process was observed. The gas temperature was measured during the 20-ns discharge by OES as well as between two discharges (100 us) by two-color OH-Planar Laser Induced Fluorescence (OH-PLIF). The maximum temperature elevation is 950 K after the pulse ; the temperature then decays exponentially with a characteristic time of 5 us. Between two successive discharges, the relative density of the OH radical was measured by OH-PLIF. An interesting result is the relatively long-lived nature of OH, with a 1/e decay time of about 50 us. Using a 0D-chemical kinetics model, the absolute OH density at the end of the pulse was estimated to 400 more or less 200 ppm. These results provide useful information to better understand the mechanisms underlying the generation of NRP spark discharges in low temperature pure water vapor.

Non-thermal plasma has a lot of ways for using in nowadays medicine. It presents many useful actions like charged particles, UV light, electric field, radicals, excited atoms and molecules. That complicated chemistry directs to uncountable synergistic interaction between cold plasma and biological systems, involve cells and tissues. This thesis is about effects of cold plasma to wound healing. Two different microwave plasma systems were used for the presented study. The first one was argon plasma torch generated by surface wave using the quartz capillary, the second one was plasma torch with reverse vortex argon flow. Diagnostics of plasma jet by optical emission spectroscopy shown the presence of active particles, which are responsible for a lot of impact of plasma treatment. Concentrations of active particles generated by plasma are dependent on conditions of plasma generation like power of generator and gas flow. For visual evidence of effects on skin caused by active particles was created simulation of skin tissue. Interaction between plasma jet and artificial skin tissue shown that UV light and temperature are not responsible for all observed effects which are noticed after plasma treatment. Some part of experiments was realized in collaboration with Medical University of Sofia in Bulgaria. The theory of positive effect to wound healing was supported by experiments based on treating artificially created wounds on laboratory mice by cold plasma. It was proved, that process of wound healing is significantly shorter after using plasma treatment in comparison with normal wound healing. Plasma treating of wound for 10 seconds in two consequent days seems like more effectively than application of plasma only one day. This Thesis was carried out as a part of international project PLASMABORDER that was supported by European commission under cohesion funds; programme INTEREG SK-CZ under contract No. 304011P709.

The main goal of this thesis was to study plasma generated by surface discharge and its application in volatile organic compound destruction. Introduction of this thesis deals with the issue of volatile organic compound. The term of volatile organic compound was defined and explained. Summary of the most important sources of volatile organic compound emissions and possible technics for their elimination was presented. This thesis drew attention on negative aspects of volatile organic compounds on human organism and on the whole environment. The problems of surface discharge and its possible application in various branches are known only few years therefore construction of plasma reactor itself was the first independent step of this work. The plasma reactor was consisted of electrode, which was created from the series of metal stripes each other separated by dielectric barrier. On the surface of the electrode, discharge was regulated and distributed. For the reason of technical limits experiment time was limited up to one minute. The experimental part describes reactor for surface discharge and other parts of apparatus in which degradation volatile organic compound was carried out. Nitrogen was used as carrier gas and it was mixed with air before entering into the reactor. Samples of compounds after degradation process were taken from reactor for the subsequent analysis. Analysis of the products proceeded in a gas chromatogram linked to mass spectrometer. The decomposition products were adsorbed in the SPME filaments or in sorption tubes. The decomposition products were analysed also through the mean of Testo 350 M/XL. This apparatus provided the information on the concentration of small molecules such as CO, H2, NO, NO2 and CxHy Hexane, cyclohexane and xylene were used as VOC examples. Analysis of GC-MS showed decomposition products of hexane, cyclohexane and xylene. The decomposition products were especially various alcohols, ketones, aldehydes and benzene compounds. The apparatus Testo 350 M/XL was unable to detect any CxHy, only large quantity of NO2. This thesis was further focused on possible factors which could have an influence on degradation of compounds, for example input power or different flow of oxygen. It was found that increasing power declined the removal efficiency. The maximum removal efficiency was 87 % for degradation of hexane at the lowest input power. Next part of this thesis was focused on diagnostics of plasma generated in the surface discharge form. The optical emission spectroscopy has been chosen as the best method for plasma characterisation. By this method, various important discharge parameters can be determined, e.g. vibration and rotation temperature. The obtained numeric value of rotation temperature was 840±80 K and vibration temperature was 1880±140 K. The obtained results may be used as a fundament for further study of VOC decomposition in surface discharge.

The present diploma thesis concerns the research of plasmachemical reduction of copper corrosion layers. The process was based on using low pressure hydrogen RF plasma in which copper samples are treated for several hours. Four series of copper corrosion layers were prepared in four different corrosion atmospheres. The first two were prepared using saturated vapors of HCl and ammonium acetate that affected copper samples for one week. The second two sets were prepared by samples dipping in HNO3 and H2SO4. EDX analysis confirms visual composition of corrosion layers – chlorides, nitrides and sulphate, respectively. The ammonium acetate produced no corrosion layers and thus this set of samples was omitted. The optical emission spectroscopy was used to find out reactions in a hydrogen RF discharge. At the first, a character of plasma without samples was taken by measuring in continuous and pulsed regime. The integral spectrum intensity (300-700 nm) and intensities of hydrogen atomic lines were observed in the dependences on hydrogen flow, power and duty cycle. After that copper samples were treaded under various conditions in continual and pulse regime, typically at pressure of 170 Pa, 200 W power and hydrogen flow rate of 10.2 ml/min. The integral OH radical spectral intensity in the range of 305 – 330 nm was used as a monitor of plasma treatment process. The experimental results showed that intensities of OH radical depended strongly on the corrosion layer kind as well as on the RF discharge mode. Reduction of corrosion layers treated in the pulsed regime was not so satisfactory then in the continuous regime probably due to lower temperature of sample during the treatment. The total supplied energy into the system was also lower in this case. The sample sputtering was observed during the reduction in continuous regime. It means the corrosion was successfully removed but the process was not stopped at that moment, so it is necessary to propose another additional monitoring process besides observing OH radicals. Our experimental results are the first step in the spread research of plasmachemical treatment of copper made archaeological artifacts.

The aim of this work is plasma diagnostic during the deposition of thin films based on organosilicone compounds. These layers have a wide range of applications mainly as protective coatings or intermediate phase in composites reinforced by glass fibers. The theoretical part of this work gives a basic fundaments of optical emission spectroscopy and mass spectroscopy and describes procedures for rotational, vibrational, and electron temperature calculations. The RF capacitive coupled discharge in configuration with planar electrodes was used with tetravinylsilane (TVS) organosilicone monomer in this study. The optical emission spectroscopy and mass spectroscopy were applied for the plasma diagnostics. The deposition process was carried out in continuous regime with applied power of 20, 25, 40, 50, 60, and 70 W, some experiments were done also in pulsed regime with duty cycle 1:1, 1:4 and 1:9 at fixed power of 50 W and 10 W when discharge was on. The atomic lines of hydrogen Balmer series and many rotational lines of molecular hydrogen were identified in the spectra. Besides them, the molecular bands of SiH, CH and C2 species were observed. The rotational temperature calculated from 0-0 CH band was in the range of 600 – 1000 K depending on the discharge conditions. The electron temperature in the range of 3600-7500 K was calculated from hydrogen atomic lines. In situ mass spectra collected simultaneously with optical emission spectra showed TVS monomer fragmentation increase with the increase of applied power in continuous regime. This result well correlated with OES in case of CH radical and hydrogen species, the other particles were mainly non-measurable by emission spectroscopy. The same results were also obtained with respect to the duty cycle parameter. The presented results clearly demonstrated the increase of monomer fragmentation with the increase of mean applied discharge power. Determination of prepared layer properties is a subject of other works and their relation to the plasma parameters will be a subject of further studies.

The main topic of this Diploma thesis is the application of low-pressure low-temperature hydrogen plasma for the treatment model samples of rusted brass. Plasmachemical treatment of metallic artifacts is a relatively new way how to remove corrosion of artifacts. The temperature of an object should not exceed 150 °C during the treatment. Corrosion layers were prepared in an ammoniac corrosion atmosphere. The corrosion formation took two weeks. Energy Dispersive X-ray Microanalysis has shown that the corrosion layer was formed by carbon, oxygen, copper, zinc, and lead. The corrosion layers were blue-colored with white crystals on the surface. Except those two colors, brown color was observed on corrosion layers, too. The plasma reactor was a quartz tube with outer copper electrodes and supplied by the RF source of 13.54 MHz. The reactive atomic hydrogen was formed in plasma discharge. This atomic hydrogen reacted with the corrosive layer containing oxygen. This reaction created an unstable OH radical, which emitted light in the region of 305–320 nm. This radiation was detected by the optical emission spectroscopy and it was applied as process monitoring quantity. Rotational temperature and intensity of OH radicals were determined from obtained data. The sample temperature was measured by thermocouple installed inside the sample volume. Rusted samples were treated by low-pressure low-temperature hydrogen plasma. 16 samples were treated at different conditions – plasma power was 100 W, 200 W, 300 W, and 400 W at continuous mode and pulse mode with duty cycle of 25 %, 50 %, and 75 %. The pressure was between 140–160 Pa at hydrogen flow rate of 50 sccm. Samples after plasmachemical treatment were grey colored with white crystals on their surface. Corrosion layers were removed by spatula. The corrosion layers of some samples were easy removable, some others were difficult. Energy Dispersive X-ray Microanalysis, which was carried out after the treatment of 2 selected samples (400 W, 50% pulse mode and 400 W, 75% pulse mode), showed different amounts of carbon, oxygen, copper, zinc, and lead compared to the rusted sample. Other elements in the treated layer were silicon, sulfur, chlorine, and fluorine.