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Ionization detector of secondary electrons for environmental scanning electron microscope
Dušek, Petr ; Zimáková, Jana (referee) ; Čudek, Pavel (advisor)
This thesis deals with problematics of a detection of secondary electrons by ionization detector for environmental scanning electron microscope. In this thesis is described the difference between scanning electron microscope and environmental scanning electron microscope. Further there is described emission and detection of the choosen signals that arise while primary electrons are interacting with a specimen in scanning electron microscope. A special emphasis is placed on a description, sorting and on the form of detection of secondary electrons. In thesis there is described principle of a function of ionization a scintilation detectors. Experimental part of thesis describes design of 3 different elctrode systems of a tabular ionization detector, which will be intended to be placed in environmental scanning electron microscope. Based on measuring with the detectors, with experimental design, there is chosen one with the highest quality of signal detection.
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Analysis of the impact of the conic aperture placement in the supersonic flow in the differentially pumped chamber
Rous, Miroslav ; Bílek, Michal (referee) ; Maxa, Jiří (advisor)
The thesis is focused on the medium dynamics simulation in the environmental scanning electron microscope. Specifically, it researches (examines) the conical aperture location effect in the differential pumped chamber and the width of the pumping channel in this chamber. The theoretical part deals with the environmental scanning microscope generally and other tools used in this thesis, e.g. ANSYS Fluen software, fluid turbulence, medium free path of molecules and electrons scattering. In the practical part, the work is focused on data processing from the ANSYS Fluent program and on their evaluation.
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Influence of working conditions on results of EDS analysis in environmental SEM
Kaplenko, Oleksii ; Chladil, Ladislav (referee) ; Čudek, Pavel (advisor)
The bachelor thesis contains an operating principle of the environmental scanning electron microscope (ESEM), issue of detection of characteristic X-Ray by using an energy dispersive spectroscopy method. The work describes detection of X-rays through silicon drifted detector, and also the principle of qualitative and quantitative X-ray microanalysis. The aim of this work is to study the influence of working conditions in the scanning electron microscope VEGA3 XMU equipped with Xflash 6 | 10 spectroscope on the results of X-ray microanalysis and their evaluations.
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Analysis of the shape of the intake ports of the current concept differentially pumped chamber
Bílek, Michal ; Vyroubal, Petr (referee) ; Maxa, Jiří (advisor)
This master´s thesis discusses the analysis of the shape of the intake ports of differentially pumped chamber for the current concept. The first part is an introduction to the microscopy issue, then it is focused on ESEM microscopes and it also includes a describtion of the Flow dynamics and a mathematical describtion. In the following chapters the software Solid Works, where the model of differentially pumped chamber is created, and the software Ansys Fluent, which is used for analysis, are described. The second part concerns the proposed concepts and the results of their simulations. At the end of the work the results are analyzed and evaluated.
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Influence of nozzle angle on gas pressure distribution in the nozzle according to Prandtl's theory
Dostalová, Petra ; Maxa, Jiří (referee) ; Šabacká, Pavla (advisor)
The thesis is focused on issue pressure distribution in the nozzle while pumping the differential pumped chambre of an environmental scanning microcope. The main task of the thesis is to find suitable design of this nozzle respect to Prandtl`s theory. In the theoretical part, there are presented microscopy as science. Afterwards the thesis is focused on environmental scanning electron microscopy and its problem and vacuum system, computer program used for preparation of simulation and study that the experimental part is based on. The experimental part evaluates the results of physical-mathematical analysis of the flow inside and behind the Laval nozzle in the experimental chambre. The results are the basis for the optimal proportions of this nozzle.
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Analysis of the impact of the baffle placement in the supersonic flow in the differentially pumped chamber
Vlasáková, Martina ; Bílek, Michal (referee) ; Maxa, Jiří (advisor)
This thesis deals with the area of the differential pumping chamber of an environmental scanning electron microscope, engaging the pressure limiting apertures and the influence of the enclosure inside the chamber. In the theoretical part, it is first called Microscopy as science, information about microscopes (division of microscopes) and electrons. Afterwards, the theory deals directly with environmental scanning electron microscopy and its problems and vacuum system, mathematical models and computational areas, basic information about the comparative study from, which the thesis is based. In the experimental part there are presented the objectives of the work and the chapter dealing with the processing of results, which are compared with the initial study using the program Ansys Fluent.
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Using Computer Aided Engineering for analyse the detector
Novotný, Marek ; Špinka, Jiří (referee) ; Maxa, Jiří (advisor)
This diploma thesis deals with electron microscopy. Examined equipment is environmental scanning electron microscope (ESEM), namely scintillation a detector of the microscope. There is solved the influence of the profile of holes in diaphragms to the resulting pressure and gas flow on the path of secondary electrons at the detector. Introductory part of thesis informs about microscopy in general, with concentration on electron microscopy; especially on scanning microscope, because research is taken just on the environmental scanning electron microscope. Another part informs about both general principles of dynamics of gases and with finite volume method. Another part deals with concrete used software and with setting of individual parameters for calculation. At the beginning of calculation are used five basic profiles of holes in diaphragms for pressure 1000 Pa in the chamber of the sample. For modelling individual shapes is used 3D parametric modeller SolidWorks. Analysis of circulation of secondary electrons through detector is made by using Cosmos FloWorks module. The most suitable type of diaphragms is chosen from measured models. Another part of diploma thesis deals with measuring of chosen types of diaphragms for more pressures in the chamber of the sample; the pressure is 200, 400, 600, 800 and 1000 Pa. The outcomes of this research are both models of pressure and speed of circulation inside the detector and graphically processed values by using different diaphragms, respectively one type of a diaphragm in different pressures. Production drawings of each diaphragm, together with calculated models, are enclosed.
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Specifications of the Ansys Fluent Solution Solver for low pressures in EREM
Šimík, Marcel ; Bílek, Michal (referee) ; Maxa, Jiří (advisor)
This thesis is focused on electron microscopy which issue is discussed at the beginning of work. The main attention is dedicated to the Environmental electron microscope, especially the differentially pumped chamber, which the thesis deals with. There is a production of an experimental chamber for analysis of shock waves on going therefore main goal of this thesis was to analyze the flow pattern in this chamber. Using the Ansys Fluent program, simulations of the characteristic flow that arises from the pumping of the vacuum chambers namely the ultrasonic flow at low pressures on which the most suitable turbulent module was applied as well as the degree of discretization was performed. The final analysis of this flow pattern is primarily focused on the localization of the shock wave which experimental evidence is to be lodged by shadow optical method as a part of the new concept of the chamber. The basis for the simulation of the chamber was taken over by Dr. Danilatos, with which the results were compared.
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Scintillation Secondary Electrons Detector for ESEM
Čudek, Pavel ; Kadlec, Jaromír (referee) ; Rek, Antonín (referee) ; Jirák, Josef (advisor)
The thesis deals with the scintillation secondary electron detector for environmental scanning electron microscope, its design and construction. The starting point was numerical simulation of electrostatic fields and electron trajectories in the electrode system of the detector and simulation of pressure distribution and flow of gases in different parts of the detector. On the basis of modeling and simulation, construction changes of the detector were gradually implemented. Detection efficiency of each version of the detector was determined by the method described in the work. This method enables to evaluate signal level from the captured images of the specimen, quality of images was stated from signal to noise ratio. The thesis describes the whole process of the detector improvement from initial state, when the detector operated with lower efficiency in the pressure range from 300 to 900 Pa, to final version that enables usage of the detector in the range from vacuum up to 1000 Pa of water vapors in the specimen chamber of the microscope.
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Scintillation SE Detector for Variable Pressure SEM
Tihlaříková, Eva ; Neděla, Vilém (referee) ; Jirák, Josef (advisor)
This project deals with the theme of environmental scanning electron microscopy (EREM). This method allows the examination of insulators and wet specimens without pretreatment and modification like drying and metallization. The principle of this method consists in using higher pressure in a specimen chamber. The pressure is within the range of 100 – 200 Pa. However, the pressure in the specimen chamber restricts the signal detection interference. The objective of the work is to explore the possibility of interference in secondary electron route detection by way of electrostatic field. The electrostatic field was realized with the system consisting of four electrodes located in front of the scintillation detector. It should have interfered the secondary electron´s trajectory to the detector chamber. The optimization of voltage on the electrodes was made by simulation program called SIMION. The simulation results were experimentally verified with laboratory EREM.
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