Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 267 for “"Engineering, Nuclear"”.
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Set up of a short magnetic lens electron spectrometer and investigation of cesium-137 and thulium-170 decay.
The present work contains the discussion on the set up of a short magnetic lens electron spectrometer, and the results of an investigation of the beta decay spectra of Cs137 and Tm170. A short magnetic lens electron spectrometer of about 21cm focal length was set up and used during the course of …
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Modeling of Wave Heated Discharges Used in Plasma Processing Reactors
Asymmetric antennas (m = +1,-1) produce 3-D components of the electric field lacking any significant symmetries and so must be fully resolved in 3-D. To investigate these processes, a 3-D plasma equipment model was improved to resolve 3-D components of the electric field produced by m = + 1,-1 …
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Kinematic and Thermodynamic Effects on Liquid Lithium Sputtering
Results suggest that preferential sputtering of deuterium atoms over lithium atoms in D-treated samples significantly decrease the absolute sputtering yield of lithium by at least 60% in the case of He+ bombardment. The secondary sputtered ion fraction for lithium bombardment has been measured for …
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A Nodal Approach to Arbitrary Geometries, and Adaptive Mesh Refinement for the Nodal Method
"The third limitation associated with the nodal method is removed by modifying an existing implementation of the NIM to incorporate fast and accurate preconditioner and solver routines. Application of this modified implementation to convection-diffusion problems proves that the coarse mesh …
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Molecular Dynamics Simulations of Carbon /Hydrocarbon -Surface Interactions Relevant to Fusion Devices
*This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirements: Internet Browser; Adobe Acrobat; Windows MediaPlayer or RealPlayer.
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Application of Lie Groups to Discretizing Nuclear Engineering Problems
In addition, a method using groups of point transformations along with Noether's theorem is shown to generate a conservation law that can be used to create a two-term recurrence relation which calculates numerically exact Green's functions in one dimension for the time-independent neutron diffusion …
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Stability and Bifurcation Analyses of Reduced-Order Models of Forced and Natural Circulation BWRs
It is hoped that results of this study are of value in demonstrating the safety features of current BWRs, and in improved design of future natural circulation BWR systems.
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Study of Breakdown/arcing for High Power RF Antennas on Fusion Applications
CCl4 and XeF2 were used as sources of halogen ions to take advantage of the ion bombardment for breakdown amelioration by modification of the electrodes. It was found that CCl4 stabilizes the emission current but increases the enhancement factor of copper electrodes. XeF 2 exhibits a …
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Instability Studies on a Spherical Inertial Electrostatic Confinement
In order to evaluate the inertial electrostatic confinement concept, it is essential to develop a reliable and flexible instability analysis method for an equilibrium plasma in a potential well. Subsequently stability of this well can be studied. As a part of this study, methods are sought to avoid …
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An Experimental Investigation of Critical Heat Flux Performance of Hypervapotron in Subcooled Boiling
A non-dimensional CHF correlation for smooth rectangular channels and the hypervapotron channel was developed and compared with experimental data in this work. In addition, a hot-spot model was developed to give predictions of critical heat flux on both plain and hypervapotron surfaces. It was …
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Temperature-Enhanced Low-Energy Ion Sputtering of Liquid Tin: Measurements and Modeling
… as a plasma-facing component in advanced thermonuclear fusion reactors and the observation of temperature-enhanced sputtering of Sn under low energy, light ion bombardment motivated further investigation of the temperature-dependent sputtering properties of Sn under various conditions. …
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"Quantum Mechanical Analysis and Numerical Optimization of a ""zero-Field"" Spin Echo Small Angle Neutron Scattering Instrument"
The numerical simulations show that the range of spin-echo length varies from 105mum up to 10-2 mum whereas the spin-echo time from 103 ns up to 10-1ns.
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Macroscopic Turbulence Modeling and Simulation for Flow Through Porous Media
Preliminary validation of the model is carried out by simulating a free stream entering the porous medium under consideration. Simulations are carried out for 75% and 95% porosities. Different inlet turbulence intensities are imposed on the free stream to test the model under different macroscopic …
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Simulation of Turbulent Flows Using Nodal Integral Method
The PMNIM is then used to study the transition to turbulence in Arnold-Beltrami-Childress (ABC) flows. These flows display the interesting phenomenon of heteroclinic cycles. The results are obtained for two wavenumbers: k = 1 (also studied earlier by other researchers) and k = 2, respectively. The …
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Adaptation of the C.H.A.D. Computer Library to Nuclear Simulations
Finally, the documentation in the public domain regarding CHAD is very limited. Therefore, a User's Manual was written for CHAD that is designed to reduce the time required to bring a new CHAD user to a productive level.
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Bombardment of Thin Lithium Films With Energetic Plasma Flows
Here, we present experimental verification of substantially reduced target surface temperature with the use of thin lithium films on surface of the target as compared to a bare target. Furthermore, optical measurements are made to determine the density and temperature of the lithium vapor cloud as …
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Three Dimensional Imaging of Helicon Wave Fields via Magnetic Induction Probes
The new diagnostic methods developed in this work (both probe characterization and analysis of measured data) provide fundamental insight into laboratory helicon plasma. The methods and results derived here will supplement and aid the design of future helicon plasma sources.
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The Electrical Impedance Responses of Protective Oxide Scales on Stainless Steels That Are Immersed in Molten Lead-Bismuth-Eutectic Alloy at Temperatures Up to 600°C
… coolant for future fast-neutron-spectrum nuclear reactors and for accelerator-driven nuclear systems, in which the LBE can also act as the spallation target. Stainless steels, out of which such systems are usually fabricated, oxidize in the molten LBE. This research used small-amplitude AC …
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Fission Gas Transport and Its Interaction With Irradiation Induced Defects in Lanthanum Doped Ceria
Various sets of quantitative experimental results were obtained to characterize the dose and temperature effects of irradiation. These results also help to benchmark simulation codes being developed with a kinetic Monte Carlo model. These experimental results include size and size distributions of …
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Error Analysis, Improvement, and New Applications of Nodal Flux Reconstruction Methods
Finally, new applications of the reconstructed flux are investigated. One application of the methodology developed in this thesis is the creation of an analytical flux distribution from the region average data from a Monte Carlo code. The specific example of the one-dimensional axial flux in a …
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