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Analysis of the gas flow in the passage of the primary electron beam differentially pumped chamber depending on the shape of the nozzle inlet
Hladký, David ; Vaculík, Sebastian (referee) ; Maxa, Jiří (advisor)
It is necessary to separate sample chamber with pressure up to 2000 Pa and the surroundings of tube with pressure 0.01 Pa with help of a differential pumped chamber at the environmental scanning electron microscope This differential pumped chamber is to be designed so that it has to manage to separate sections with very different pressures sufficiently and in the trajectory of transitting (overflying) prime electrons the average value of pressure and density has to be as low as possible, so that it would occure the lowest diffusion of these electrons, which is caused by collisions of electrons and air molecules too. It were created axisymmetric 2D models variant of Differentially pumped chamber with different opening angles of the clone, which were analyzed to choose the best variant. The Ansys Fluent systeme using finite volume method for analysis of fluid flow was used for analysis.
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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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Analysis of the gas flow when pumping vacuum for newly designed scintillation detector
Poruban, Milan ; Vaculík, Sebastian (referee) ; Maxa, Jiří (advisor)
The aim of this thesis is to study the issue of eniveromental scanning electron microscopy and pumping gas to create vacuum in the newly designed scintillation detector. Further, creating a model of recently proposed scintillation detector and simulating and analyzing pumping gas in differentially pumped chamber of detector. The theoretical part deals with electron microscopy, electron sources, electron optics and secondary electrons detectors. It is also presented which signals are generated by the electron beam on the surface of a solid. Further fluid flow issues and equations describing the flow in the solved chamber are dismantled. Furthermore, the impact of gaseous environment on the trajectory of primary electrons, because there are collisions of primary beam with atoms and molecules of gas. The following section discusses creating, quality and importance of the network in mathematical modelling. A method of a final volume used to calculate the differential equations describing the flow of gas at the premises of the detector is described . The practical part consists in creating a model of scintillation detector and analyzing the gas flow in drawing a vacuum in the newly designed scintillation detector. At the end the simulation results of gas flow are compared for different variants of apertures and various pressures on the neck of a scintillation detector designed for optimum performance of the detector. The outcome of this thesis is model of newly designed scintillation detector with optimized shapes of apertures according to functional requirements.
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Evaluation of gas flow in the scintillation detector at different profiles and sizes of holes in the screens that have shaped the network
Truhlář, Michal ; Špinka, Jiří (referee) ; Maxa, Jiří (advisor)
This work deals with the flow of gas in the scintillation detector. Thesis describes the function of an electron microscope, the composition, distribution and development of microscopes from the earliest to modern. The work also includes familiarization with SolidWorks 3D modeling in which is the electron microscope modeled and Cosmos FloWorks in which they are carried out simulations of gas flow. The paper is focused on the flow of gas in various shapes of the screen and various pressures in chamber of specimen. The results of the analysis of both apertures variants are compared with the request to minimize the pressures in the trajectory of the secondary electrons of well as in the chamber of specimen.
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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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Study of the possibility of using Tesla's turbine as a source of energy
Šedina, Martin ; Maxa, Jiří (referee) ; Kazda, Tomáš (advisor)
The master thesis deals with the currently used types of water turbines and next part of the thesis deals with the theory of Tesla turbine. The theoretical part discusses water wheels, water turbines with their types and models which are described in the work. The thesis also discusses the construction of the Tesla turbine, its possibilities of using, inside principles and information about Tesla´s patent. The practical part contains the design of the Tesla turbine with modifications for increasing efficiency. The thesis describes production and assembly of turbine and the technology used for production of the turbine. There is also described how the turbine was measured and there are results of measurements of the turbine.
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Comparison of flow conditions in the gas detector used in the aperture and screen
Hubáček, Jiří ; Špinka, Jiří (referee) ; Maxa, Jiří (advisor)
The first part of the thesis deals with electron microscopy and physical model fluid flow. In the next part, a three-dimensional model is created in programme SolidWorks. It is the model of scintilating detector with aperture or screen with three hundred little apertures. These models are submitted to analysis focusing on investigation of the gas flow at different pressure in chamber of specimen ESEM using Cosmos FloWorks system. The results of the analysis of both apertures variants are compared with the request to minimize the pressure in the trajectory of the secondary electrons as well as in the chamber of specimen.
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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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