Physics Commons^™

The Application Of Tomographic Reconstruction Techniques To Ill-Conditioned Inverse Problems In Atmospheric Science And Biomedical Imaging, Vern Philip Hart Ii

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Tomography is an imaging technique in which 3D models of objects are created from several 2D projections viewed at different angles. When the number of available projections is limited, the resulting data are said to be sparse. This restriction is often a direct result of the imaging geometry used to acquire the data. One-sided views and a small number of receivers can reduce the range of available projections, which makes the object more difficult to reconstruct. Approximate solutions to difficult imaging problems can be obtained using a class of iterative algorithms known as the algebraic reconstruction techniques (ARTs). The presented …

In Situ Measurements Of Electron-Beam-Induced Surface Voltage Of Highly Resistive Materials, Joshua Hodges

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Surface charging and subsequent electrostatic discharge due to interactions with the space environment is one of the primary concerns of spacecraft charging studies. Laboratory measurements of the evolution of surface voltages and dissipation currents under simulated space conditions are the primary method used to determine the response of key spacecraft materials to diverse incident fluxes. Increasing the database of information for the electronic properties of insulating materials can assist spacecraft designers in mitigating the harsh effects of the space environment.

The Utah State Materials Physics Group, with the funding of the NASA James Webb Space Telescope project and personnel support …

The Effect Of Growth Parameters On The Height And Density Of Carbon Nanotube Forests, Robert Welch Call

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Rolled-up graphene sheets, known as carbon nanotubes, are grown in vertically aligned arrays called carbon nanotube forests (CNTFs). CNTFs make extremely dark surfaces. They are being investigated for use on space crafts as calibration surfaces and to protect optical sensors from unwanted signals. These CNTFs are grown by injecting a precursor consisting of a metal catalyst particle and a hydrocarbon component into a furnace at high temperature (~700°C). This study investigates the influence of several different growth parameters on the final height and density of the CNTF. Height and density influence the absorbance of the surface at different wavelengths.

A 2d Finite Element/1d Fourier Solution To The Fokker-Planck Equation, Joseph Andrew Spencer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Plasma, the fourth state of matter, is a gas in which a significant portion of the atoms are ionized. It is estimated that more than 99% of the material in the visible universe is in the plasma state. The process that stars, including our sun, combine atomic nuclei and produce large amounts of energy is called thermonuclear fusion. It is anticipated future energy demands will be met by large terrestrial devices harnessing the energy of nuclear fusion. A gas hot enough to produce the number of atomic collisions needed for fusion is necessarily in the plasma state. Therefore, plasmas are …