Physical Sciences and Mathematics Commons^™

The Development And Use Of A Secondary Electron Yield Database For Spacecraft Charge Modeling, Phillip Lundgreen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Charge modeling of electron-solid interactions requires a detailed and accurate compilation of experimental data on which to base its physics and against which to test its predictions. Historically researchers used methods involving individual research or information taken from existing, vague, databases that were often found wanting. To streamline the charge modeling process, a collection of data has been assembled and categorized based upon surface morphology and contamination from various published sources and existing databases. The quality and quantity of the compilation vary widely with very little information offered with regards to surface conditions of various materials (contamination, morphology, etc. ...). …

Effects Of The Radiation Belt On The Plasmasphere Distribution, Stefan Thonnard

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study examines the interaction of plasma, ions and electrons created by Solar illumination in the Earth’s upper atmosphere, that travels along magnetic field lines filling the Plasmasphere, and the naturally occurring trapped particles known as the outer radiation belt. Although these two science disciplines have been largely worked independent of each other due the vast differences in the energy of the particles, recent satellite observations indicate a large population of particles with lower energy and greater mass also exist in the outer radiation belt. This study shows that during conditions of low solar output in an 11-year cycle, these …

Embedded-Atom-Method Modeling Of Alkali-Metal/Transition-Metal Interfaces, Jake D. Christensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Understanding the thermal properties of materials is essential to using those materials for technological advancement which can benefit civilization. For example, it has been proposed that essential components of tokamaks, devices which perform fusion, be made out of tungsten with a thin layer of lithium on the surface. To that end, this thesis seeks to calculate the thermal properties of a layer of alkali atoms, like lithium and sodium, on tungsten and molybdenum substrates. We use an Embedded Atom Method (EAM) model to perform our calculations. This type of model has been widely used to describe the interaction between atoms …

Electron Emission And Transport Properties Database For Spacecraft Charging Models, Phil Lundgreen

Theses and Dissertations

Modeling the rate and likelihood of spacecraft charging during spacecraft mission is critical to determine mission length, proposed spacec­raft attitude, and spacecraft design. The focus of this work is the creation and utilization of a database of secondary electron yield (SEY) measurements for a host of materials to increase accuracy in spacecraft modeling. Traditional methods of SEY data selection for input into spacecraft charging codes typically include the use of compiled materials databases incorporated in charging codes or selecting values from a specific scientific study. The SEY database allows users to select data inputs based upon the details associated with …

Massive Graviton Spectra In Supergravity, Kevin Dimmitt

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Development of a unified theory of physics would pave the way for new research and technology development for many years to come. Unfortunately, the two best current theories explaining nature, the Standard Model of particle physics and general relativity, do not seem to be compatible, requiring the development of more complicated models which contains both of these at their respective limits. Supergravities are one set of theories which may, at least in part, provide hints as to how it may be possible to unify physics into a single model.

This research project follows from a line of investigation which the …

Storm-Time Equatorial Thermospheric Dynamics And Electrodynamics, Luis A. Navarro Dominguez

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

We present the first complete study of the dynamics of the equatorial upper atmosphere (180-350 km) during periods of strong magnetic activity driven by the Sun, which are generally referred as geomagnetic storms. These storms have the potential to considerably affect satellite-based communications and navigation systems among other severe technological challenges. We used large databases of two of the most important parameters at these altitudes, which are the velocities of the neutral and ionized gas (plasma) referred to as neutral winds and plasma drifts. These measurements were acquired in the Peruvian equatorial region by the Jicamarca radar and by a …

Model-Based Properties Of Earth's Protective Shield: Relating Ut-Based Dependencies Of The Open/Closed Boundary, Cutoff Latitude, And L-Shell Parameter With Polar Cap Absorption Events, David A. Smith

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

High frequency radio continues to be an important communications medium. For example, commercial airlines use high frequency radios as their primary communications mode during transpolar crossings. It has been estimated that over 7000 transpolar flights occur each year. Unfortunately, during geomagnetic storms high frequency communications can become unreliable, especially near Earth's Polar Regions.

Space weather forecasters are burdened with the responsibility of predicting how radio signals might be affected during geomagnetic storms and passing that important information on to commercial airlines, allowing them to adjust flight plans accordingly. Such adjustments can be costly, but are necessary to ensure safety of …

Studies On Secondary Electron Emission Induced Charging In Dielectric Materials: Novel Methods And Applications For Space And Plasma Technologies, Leandro Olano Garcia

Theses and Dissertations

The interaction of ionizing radiation with matter is of critical importance in many areas of science and technology such as space and plasma technology. Secondary electron emission is a direct consequence of electron irradiation on materials. To characterize materials in terms of secondary electron emission, the secondary emission yield (SEY) and the energy spectra of the secondary electrons are key physical properties. Secondary emission yields of materials are usually too high to avoid Multipactor effect or other related phenomena in applications for space. In addition, the measurement of electron energy spectra of secondary electrons in dielectric materials is a challenge …