Theses and Dissertations from UMD

Permanent URI for this communityhttp://hdl.handle.net/1903/2

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM

More information is available at Theses and Dissertations at University of Maryland Libraries.

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    NEUTRON SHIELDING DESIGN FOR CENTRIFUGALLY CONFINED SPACE PROPULSION SYSTEM
    (2023) Parsons, Jennifer; Sedwick, Raymond J; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This thesis presents a preliminary neutron shielding design for the HTS coils of a centrifugally confined fusion space propulsion system, which is a promising technology for future space travel. The design process involved a comprehensive study of neutron transport, material selection, and shielding optimization using MCNP and MATLAB simulations. First, the neutron attenuating properties of reflector, moderator, and absorber candidate materials were compared in MCNP. The thickness and composition of the shield were optimized from the resulting MCNP data. Next, two overall reactor and shielding geometry models were developed in MATLAB to estimate the total mass of the HTS shielding for both coils. The first model assumed a point neutron source and uniform thickness across the surface area of the shield. The second model improved upon the first by considering a source distribution and the varying distance between the source and surface of the shield. Both D-T and D-D fuel cases were run with the model and the resulting mass estimates were used to compare the specific mass to the state-of-the-art technology.
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    Microwave Emission and Electron Temperature in the Maryland Centrifugal Experiment
    (2013) Reid, Remington R.; Ellis, Richard F; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The use of two magnetised plasma waves as electron temperature diagnostics for the Maryland centrifugal ecperiment (MCX) are explored. First, microwave emission in the whistler mode is examined and ultimately found to be a poor candidate for diagnostic purposes owing to reflections from elsewhere in the plasma confusing the signal. Second, the electron Bernstein wave is found to offer promise as means to measure the radial electron temperature profile. Several numeric codes are developed to analyze the observed microwave emission and calculate the elec- tron temperature profile. Measurements of electron Bernstein wave emission indicate that the electrons in the plasma attain temperatures close to 100 eV. Clear evidence is shown that the measurements are not influenced by reflections or emission from hot (Te > 1keV) superthermal electrons. The measured electron temperature is shown to be in reasonable agreement with recent measurements of the plasma ion temperature.