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Compare weld from CO2 laser and fiber laser
Leidorf, Michal ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
The project compares the technology of welding of CO2 laser and fiber laser in terms of engineering study, the welds will be made by same welding conditions on two materials (S235JRG2 a X5CrNi 18-10), by using different protective gases (Helium and Argon). In the terms of literal background research both the technologies and questions of laser welding are described. The geometry of welds is carried out in the experimental part. The final results of the experiment are concluded at the end of the diploma thesis.
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Diagnostic of nitrogen post-discharge by optical emission spectroscopy
Kabeláčová, Kateřina ; Slavíček,, Pavel (referee) ; Mazánková, Věra (advisor)
The aim of this thesis is diagnose post-discharge nitrogen plasma with optical emission spectroscopy. There is long interest of investigated of nitrogen post-discharge plasma and study how to use it in theory as well as in practice. All results were measured with method of optical emission spectroscopy of post-discharge plasma. Discharge was generated by direct-current voltage generator with flowing regime. In this thesis was used for different series of experiments. First experiment was performed with adding water vapour into argon plasma. Measuring was processed at constant current 140 mA, voltage 1.5 V and pressure 1 000 Pa. It was changed flow rate and for each individual flow rate was measured in range 1–25 cm from end of active discharge. Second experiment was with adding nitrogen into argon plasma. Measuring was processed at constant current 140 mA, voltage 1.5 V and pressure 1 000 Pa. We were changing flow rate of nitrogen (0,2 sccm, 0,4 sccm and 0,8 sccm). For each individual flow rate was same experiment with changing distance from active discharge. Third experiment was about adding mercury vapour into nitrogen post-discharge. Measuring was processed at constant current 120 mA, voltage 3.5 V and pressure 1 000 Pa. Measuring was performed with two configuration: with diaphragm and without it. Last experiment was about adding air into argon plasma. Measuring was processed at constant current 140 mA, voltage 1.0 V and pressure 1 000 Pa. Temperature of outer face of tube was measured by thermocouple and infrared thermometer, was measured for last two experiments (argon – air and nitrogen). During experiments with pure nitrogen was visible phenomenon called pink afterglow which is manifested by noticeable increase pink coloration. Optical emission spectrums post-discharge was take at various range of wavelength. At argon with water vapour was 280–600 nm and at adding nitrogen into argon was at range 320–500 nm. At added mercury vapour into nitrogen was 320–600 nm. For experiment argon – air was wavelength range 320–600 nm. From results of experiments were designed dependencies of calculated intensity from measured spectra on distance from active discharge. Also were constructed dependencies of measured temperature on distance from active discharge.
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Study of plasma species by mass spectroscopy
Bureš, Michal ; Čáslavský, Josef (referee) ; Čech, Vladimír (advisor)
Plasma polymer films of tetravinylsilane and mixture of tetravinylsilane and oxygen gas were deposited on silicon wafers. Oxygen gas was mixed in tetravinylsilane to improve the compatibility of thin films on glass substrates. Mass spectroscopy was employed during the cleaning of the deposition chamber to check residual gases and process gases, during plasma deposition to monitor neutral plasma species and to follow plasma stability.
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Influence of Inert Atmosphere on Surface Wetting in Lead Free Soldering
Nestrojil, Michal ; Špinka, Jiří (referee) ; Starý, Jiří (advisor)
This master´s thesis dealing with study of influence of inert atmosphere on the wettability of soldered surfaces. The theoretical part is discussed the issue of the soldering, solder joint, oxidation, and inert atmosphere. The glass cover with internal inert gas preheating for the wetting balance testing was prepared in the practical part. With this adjustment were realised tests, in which was examined the effect of the inert gases on the wettability of different materials combination. Further experiments were focused on plasma surface cleaning as possible flux substitution. The evaluation of these experiments were discussed in the end of this master´s thesis. Some of topics were designed for further experiments.
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Deposition and optical properties of thin films and layered structures by PECVD
Kucharčík, Jan ; Boušek, Jaroslav (referee) ; Čech, Vladimír (advisor)
Thesis in theoretical part is focused on the principle of spectroscopic ellipsometry and formation of thin films by plasma-enhanced chemical vapor deposition (PECVD). In the experimental part we describe the deposition system, ellipsometer and mathematical evaluation of ellipsometric data, materials used for film formation and processing of the samples. Single-layer and multilayer structures of polymeric materials were prepared. We revealed that the optical properties of thin films are independent of film thickness. We also described the effect of the effective power and deposition gas mixture on optical properties of thin films.
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Comparison of organic dye decomposition in various plasma systems
Dotsenko, Anastasia ; Králová, Marcela (referee) ; Kozáková, Zdenka (advisor)
This bachelor thesis deals with the comparison of the degradation of organic dyes (namely: Saturn Red L4B (Direct Red 79) and Indigo Carmine (Acid Blue 74)) in different plasma systems and the general characteristics of the optical emission spectrometry of a microwave plasma nozzle. It briefly summarizes basic information about plasmas and the processes involved. The theoretical part focuses on basic information about plasmas and their processes, basic information about dyes and their degradation methods. Plasma contains a number of active particles such as hydroxyl radicals, nitrogen oxide radicals, excited nitrogen molecules, atomic nitrogen, argon and oxygen. All these particles, together with photons generated by the plasma, are useful in environmental applications. The experimental part focuses on treating a sample of model dyes in selected plasma systems generating plasma above the liquid surface (microwave surface wave discharge, dielectric barrier discharge with liquid electrode) or below it (plasma nozzle in liquid) and evaluating their decomposition rate. Characterization of the distribution of active particles along the plasma axis of a high frequency plasma jet in argon and determination of the conditions in the plasma with respect to the environmental applicability of the system.
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Study of Positive Column in Glow Discharge under Medium Pressures Using Computational Experiment
Laca, Marek ; Hrachová, Věra (advisor) ; Novák, Stanislav (referee) ; Roučka, Štěpán (referee)
The positive column of the oxygen and argon-oxygen direct current glow discharge was investigated using a fluid plasma model at pressures around hundreds of pascals and discharge currents from ten to forty miliampers. The model describes the infinitely long positive column in cylindrical discharge tube. It is based on the continuity equation for particle concentration with the collisional right hand side. The model utilises the drift-diffusion approximation of particle flux and the mean-electron-energy approximation for the description of the electron interaction. The radial profile of particle concentration and interaction with the glass wall of the discharge tube is taken into account. The model predicts the electric field and the particle concentration in the positive column. The simulation results were compared with the measured intensity of electric field strength in the oxygen and argon-oxygen mixture. The impact of discharge conditions, like the pressure and gas composition, on the properties of the positive column was investigated. The model confirmed that the strength of longitudinal electric field at medium pressures is about 40 V/cm in oxygen, molecular gas, and it is about 3 V/cm in argon, noble gas.
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Study of Positive Column in Glow Discharge under Medium Pressures Using Computational Experiment
Laca, Marek ; Hrachová, Věra (advisor) ; Novák, Stanislav (referee) ; Roučka, Štěpán (referee)
The positive column of the oxygen and argon-oxygen direct current glow discharge was investigated using a fluid plasma model at pressures around hundreds of pascals and discharge currents from ten to forty miliampers. The model describes the infinitely long positive column in cylindrical discharge tube. It is based on the continuity equation for particle concentration with the collisional right hand side. The model utilises the drift-diffusion approximation of particle flux and the mean-electron-energy approximation for the description of the electron interaction. The radial profile of particle concentration and interaction with the glass wall of the discharge tube is taken into account. The model predicts the electric field and the particle concentration in the positive column. The simulation results were compared with the measured intensity of electric field strength in the oxygen and argon-oxygen mixture. The impact of discharge conditions, like the pressure and gas composition, on the properties of the positive column was investigated. The model confirmed that the strength of longitudinal electric field at medium pressures is about 40 V/cm in oxygen, molecular gas, and it is about 3 V/cm in argon, noble gas.
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Diagnostic of nitrogen post-discharge by optical emission spectroscopy
Kabeláčová, Kateřina ; Slavíček,, Pavel (referee) ; Mazánková, Věra (advisor)
The aim of this thesis is diagnose post-discharge nitrogen plasma with optical emission spectroscopy. There is long interest of investigated of nitrogen post-discharge plasma and study how to use it in theory as well as in practice. All results were measured with method of optical emission spectroscopy of post-discharge plasma. Discharge was generated by direct-current voltage generator with flowing regime. In this thesis was used for different series of experiments. First experiment was performed with adding water vapour into argon plasma. Measuring was processed at constant current 140 mA, voltage 1.5 V and pressure 1 000 Pa. It was changed flow rate and for each individual flow rate was measured in range 1–25 cm from end of active discharge. Second experiment was with adding nitrogen into argon plasma. Measuring was processed at constant current 140 mA, voltage 1.5 V and pressure 1 000 Pa. We were changing flow rate of nitrogen (0,2 sccm, 0,4 sccm and 0,8 sccm). For each individual flow rate was same experiment with changing distance from active discharge. Third experiment was about adding mercury vapour into nitrogen post-discharge. Measuring was processed at constant current 120 mA, voltage 3.5 V and pressure 1 000 Pa. Measuring was performed with two configuration: with diaphragm and without it. Last experiment was about adding air into argon plasma. Measuring was processed at constant current 140 mA, voltage 1.0 V and pressure 1 000 Pa. Temperature of outer face of tube was measured by thermocouple and infrared thermometer, was measured for last two experiments (argon – air and nitrogen). During experiments with pure nitrogen was visible phenomenon called pink afterglow which is manifested by noticeable increase pink coloration. Optical emission spectrums post-discharge was take at various range of wavelength. At argon with water vapour was 280–600 nm and at adding nitrogen into argon was at range 320–500 nm. At added mercury vapour into nitrogen was 320–600 nm. For experiment argon – air was wavelength range 320–600 nm. From results of experiments were designed dependencies of calculated intensity from measured spectra on distance from active discharge. Also were constructed dependencies of measured temperature on distance from active discharge.
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