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Methods of Preparation and Characterization of Experimental Field-Emission Cathodes
Knápek, Alexandr ; Luňáček, Jiří (oponent) ; Lazar, Josef (oponent) ; Grmela, Lubomír (vedoucí práce)
This PhD thesis describes, and covers the preparation of field-emission cathodes that represent a high-quality, inexpensive source of electrons for devices that work with a focused electron beam. In this work, an improved method of electrochemical fabrication is used for the preparation of a composite field-emission cathode. The composite structure improves current stability in comparison to tungsten-based pure field-emission cathodes. Improvements to the technology used were implemented on the basis of findings obtained using spectrum noise diagnostics, which are based on measuring and evaluating the emission current in the time and in frequency domains. Additionally, noise spectroscopy provides important information about charge transport, electron mobility, and lifespan, which is essential for future research. Results obtained using the experimental method have been further supplemented with theoretical data provided by a computer simulation in order to establish characterization procedures for improved field-emission cathodes.
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Methods of Preparation and Characterization of Experimental Field-Emission Cathodes
Knápek, Alexandr ; Luňáček, Jiří (oponent) ; Lazar, Josef (oponent) ; Grmela, Lubomír (vedoucí práce)
This PhD thesis describes, and covers the preparation of field-emission cathodes that represent a high-quality, inexpensive source of electrons for devices that work with a focused electron beam. In this work, an improved method of electrochemical fabrication is used for the preparation of a composite field-emission cathode. The composite structure improves current stability in comparison to tungsten-based pure field-emission cathodes. Improvements to the technology used were implemented on the basis of findings obtained using spectrum noise diagnostics, which are based on measuring and evaluating the emission current in the time and in frequency domains. Additionally, noise spectroscopy provides important information about charge transport, electron mobility, and lifespan, which is essential for future research. Results obtained using the experimental method have been further supplemented with theoretical data provided by a computer simulation in order to establish characterization procedures for improved field-emission cathodes.
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