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Microstructure And Work Function Of Dispenser Cathode Coatings: Effects On Thermionic Emission, Phillip D. Swartzentruber
Microstructure And Work Function Of Dispenser Cathode Coatings: Effects On Thermionic Emission, Phillip D. Swartzentruber
Theses and Dissertations--Chemical and Materials Engineering
Dispenser cathodes emit electrons through thermionic emission and are a critical component of space-based and telecommunication devices. The emission of electrons is enhanced when coated with a refractory metal such as osmium (Os), osmium-ruthenium (Os-Ru), or iridium (Ir). In this work the microstructure, thermionic emission, and work function of thin film Os-Ru coatings were studied in order to relate microstructural properties and thermionic emission.
Os-Ru thin film coatings were prepared through magnetron sputtering and substrate biasing to produce films with an array of preferred orientations, or texture. The effect of texture on thermionic emission was studied in detail through closely-spaced …
Combining Monte Carlo Transport And Level Set Surface Evolution For Modeling Vapor Phase Deposition Of Thin Films Over Sub-Micron Features, John Lewis Smith
Combining Monte Carlo Transport And Level Set Surface Evolution For Modeling Vapor Phase Deposition Of Thin Films Over Sub-Micron Features, John Lewis Smith
Graduate Theses - Chemical Engineering
A hybrid scheme is used to model the vapor phase deposition of thin films at the feature scale. The transport of the chemical species to the substrate surface is modeled with a Collisionless Direct Simulation Monte Carlo (DSMC) method. The Level Set Method is used to model the growth of the thin-film on the substrate. The convergence criteria for these methods were not found in literature.
The governing equations for the Level Set Method are, in general, non-linear partial differential equations. The coupling of the DSMC Method with the Level Set Method results in a set of non-Gaussian stochastic non-linear …