Physics Commons^™

Divergence-Free Tensor Densities In Two Dimensions, Tyler Hansen

All Graduate Theses and Dissertations, Fall 2023 to Present

In physics, a common method for exploring the way a physical system changes over time is to look at the system’s energy. Roughly speaking, the energy in these systems are either motion-based (kinetic energy, a bullet in flight) or position-based (potential energy, a rock sitting at the top of a hill). The difference between the system’s total kinetic and potential energies is quantified by an expression called the Lagrangian. Using a special procedure, this Lagrangian is massaged to produce a group of equations called the Euler-Lagrange equations; if the initial configuration of the system is provided, the solution to these …

Dynamics And Scaling Of Particle Streaks In High-Reynolds-Number Turbulent Boundary Layers, Tim Berk, Filippo Coletti

Mechanical and Aerospace Engineering Faculty Publications

Inertial particles in wall-bounded turbulence are known to form streaks, but experimental evidence and predictive understanding of this phenomenon is lacking, especially in regimes relevant to atmospheric flows. We carry out wind tunnel measurements to investigate this process, characterizing the transport of microscopic particles suspended in turbulent boundary layers. The friction Reynolds number Re_𝜏 = O(10⁴) allows for significant scale separation and the emergence of large-scale motions, while the range of viscous Stokes number St⁺ = 18–870 is relevant to the transport of dust and fine sand in the atmospheric surface layer. We …

Nalidarturbopauseshear, Titus Yuan

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The USU Na lidar has been upgraded to be able to measure temperature and winds in the lower thermosphere up to ~ 115 km routinely. The new capability, coupled with the existing nightglow instruments at USU, enables the investigation of the extreme large wind and shears in this region and their correlation to the atmospheric gravity waves activities in the upper mesosphere.

A Simple Method For Determining Shallow Charge Distributions In Dielectrics Via Pulsed Electroacoustic Measurements, Zachary Gibson, J. R. Dennison

Journal Articles

The understanding of charge dynamics in dielectric materials is paramount in mitigating electrostatic discharge events for spacecraft. The most critical spacecraft charging events are found to result from incident electrons in the energy range of 10 keV to 50 keV. The charge embedded in dielectric materials in this energy range are deposited a distance into the material on the order of a few to tens of microns. One way to measure and understand the deposited charge is via pulsed electroacoustic measurements (PEA). However, the typical PEA spatial resolution of ~ 10 μm is not sufficient to resolve or discern charge …

The Derivation Of Sodium Density In The Mesosphere And Lower Thermosphere From The Na Lidar Photon Counting Profiles, Xiaoqi Xi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Derivation of Sodium (Na) number density from the Na lidar observations requires the in situ temperature and wind information because the absorption cross-section of the Na atom is a function of these dynamic parameters. The Na number density above ~ 110 km altitude was difficult to derive with the conventional algorithm, however. The standard output of the Na number density that utilizes the lidar-measured wind and temperature information falls short at ~ 110 km altitude and above due to the relatively large measurement uncertainties in the two critical parameters (low signal-to-noise ratio). Therefore, an innovative algorithm that may drive the …

Signatures Of Black Holes, Alexandra B. Chanson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In this defense I will describes three approaches to learn more about the relationship between the dynamics of black-holes and the distinctive signatures of a black hole systems: infinitesimal changes in the black hole background producing field excitations relating new fundamental black hole thermodynamic relations, mechanisms powering relativistic black hole jets and spontaneous symmetry breaking in five space-time dimensions, and physical signatures of black hole event horizons as conformal field theory duals (in both d=4,5 dimensional axisymmetric spacetimes).

The Time-Dependent Ionospheric Model Using A Tec-Driven Servo: An Investigation Of The Capabilities And Limitations, Jenny Rebecca Whiteley

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The ionosphere is a region of the atmosphere with a high density of electrons. These electrons affect the behavior of any electromagnetic wave that passes through the ionosphere. Communication and geolocation systems, such as traditional radio and Global Positioning Systems, depend on emitted electromagnetic signals being picked up by a receiver. The presence of the ionosphere affects the behavior of the signal and the quality of the service. Hence, the interactions between electromagnetic waves and the ionosphere provide a major motivation to understand, research, and successfully model and predict the ionosphere and its physical phenomena. This study focused on determining …

Precise Determination Of Charge Distributions In Electron Irradiated Polymers Via Pulsed Electroacoustic Measurements With Applications To Spacecraft Charging, Zachary Gibson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Understanding how charge builds up and moves around in materials that are highly insulating, such as dielectrics, is important for many applications from power transmission to spacecraft charging. The leading cause of issues in spacecraft due to interactions with the space environment is spacecraft charging. That is, the accumulation of charge on insulating materials leads to arcing and sparking aboard the spacecraft. The most critical charging occurs due to electrons in a particular energy range of 10-50 keV. Electrons with these energies can travel 1’s to 10’s of microns into relevant materials. To measure where the charge is embedded and …

Radon In Utah Homes, Madison Mackay

Physics Capstone Projects

Radon gas can be found nearly everywhere. It is formed by the decay of radium, which is found in rocks, soil, plants, and animals. Radon gas can become trapped in buildings and is dangerous at high levels. It is particularly known to be high in many areas of the state of Utah. It is important for the average citizen in Utah to understand more about radon and what levels they may be exposed to. An experiment was done to try an alternate, faster method of testing for radon gas. This experiment was performed in several different locations in Utah. While …

Preparation, Characterization And Electron Yield Analysis On Highly Insulating Granular Particles, Heather Allen

Physics Capstone Projects

This study focuses on obtaining reliable electron yield measurements of highly insulating granular particles of various shape, size, and composition. Measurements of this kind have long been considered too difficult to collect on granular samples due to experimental complexities leading to a critical knowledge gap in the fundamental electrostatic behaviors of dust. A significant portion of this study was spent on preparing and characterizing granular samples before any type of measurement took place. Particles of varying sizes ranging from ~1 μm to ~100 μm, shapes including cubical, spherical, and angular, and composition including NaCl, MgO, Al₂O₃ and …

Methods For Preparing And Characterizing Granular Materials For Electron Yield Measurements, Tom Keaton

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

This work presents a systematic study on sample preparation methods and accuracy of electron yield (EY) measurements of highly insulating, granular materials. EY measurements of highly insulating materials, especially those with high EY, are challenging due to the effects of sample charging even for very low fluence electron probe beams. EY measurements of particulates are complicated by: (i) roughness effects from particulate size, shape, coverage, and compactness; (ii) particle adhesion; (iii) substrate contributions; and (iv) electrostatic repulsion and potential barriers from charged particles and substrates. Numerous methods were explored to rigidly affix particles on conducting substrates at varying coverages for …

Engineering Lab Building Telescope Manual, Aidan L. Tueller

Physics Capstone Projects

In partnership with Dr. Jan Sojka, head of the Physics Department, a plan was created to make the telescope on top of the Engineering Lab building operational again for either staff, students, classes, or labs to use. The telescope was purchased through funds by Utah NASA Space Grant Consortium. This paper will contain basic information about how to operate the telescope and use its equipment. There is an online manual from Meade that is much longer but goes into much more detail about individual pieces and specific parts of the telescope.

Metasurfaces For Holography, Scott Howell

Physics Capstone Projects

Holography uses the interference of light waves to store information about an object, which can then be seen from different angles to create a partial 3D view. A simple experiment can be done using a laser diode, photographic plate, and a set of dice to create a holographic image. The holographic film is thin and can only hold a single image. Reflection holography can create a 3D diffraction pattern and allows more information to be packed into a single medium. Computer generated holograms can be designed to create holograms without a real object to be used in augmented reality. High …

A Classification Of Tensors In Ecsk Theory, Joshua James Leiter

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

You might have heard of Einstein’s theory of General relativity (GR): it is the one where mass and energy curve the fabric of spacetime to create gravity. This is the major theory which allows communication through satellites and our GPS to work too! Wormholes have interested me, but there are some issues about forming them in GR. Interestingly enough, elementary particles are also characterized by their spin in the standard model. However, intrinsic spin is nowhere geometrically coupled to the geometry of spacetime in Einstein’s theory. Later, Élie Cartan, Dennis Sciama, and Tom Kibble all flushed out adding different aspects …

Light Scattering From Periodic, Conducting Nanostructures, Wesley Kenneth Mills

Undergraduate Honors Capstone Projects

A material with broadband light absorbing capabilities has the potential for much usefulness in devices such as photovoltaics and thermoelectrics. By energy conservation, a non-transparent material with low reflectance will be highly absorbing. Thus, much research has been devoted to understanding what makes material having low reflectance across a wide wavelength spectrum.

The importance of a material’s electronic structure in determining reflectance is well-established. Current research is revealing the additional importance of surface architecture in the reflective properties of a material. A metasurface is a two-dimentional material with physical features at or smaller than the wavelength of light considered. These …

The Kp Index And Behavior Of Quiet Periods, Collette Walbeck

Physics Capstone Projects

The Kp-index quantifies the electromagnetic effects in the Earth’s atmosphere and is used in a variety of scientific fields. Higher Kp values tend to be the focus in these fields as they relate to high solar activity and geomagnetic storms. This study aimed to examine the significance, if any, of lower Kp indices. A simple data analysis was performed on continuous sequences of low Kp values, deemed Quiet Periods. Both the daily average of the values and the full set of Kp data were used. A decaying exponential relationship was discovered between the length of these periods and their frequencies …

High Frequency Radio Communication, Tyler Larsen

Physics Capstone Projects

High frequency radio communication has been the most reliable form of communication for many decades. Over that period, we have learned and experienced times of enhanced signals along with complete radio blackouts. The purpose of this research is to collect and analyze radio signal data to see the evidence of various reasons as to why these phenomena occur. A radio antenna was set up at USU campus to retrieve the signals from beacon networks across the globe that transmit signals every 15 minutes. By tracking a few of these signals we can locate the times of discrepancies in the signals …

Effectiveness Of Multilayer Graded-Z Forms Of Radiation Shielding, Brinley Packer

Physics Capstone Projects

This study explored how different forms of radiation shielding were more or less effective than standard single-layer shielding. Beta and gamma radiation sources were used and measured using a Geiger counter to determine how well the various forms of shielding protect against the radiation. The shielding effectiveness of standard homogeneous materials (e.g., graphite, carbon/epoxy composites, aluminum, and lead) of various thicknesses for different radiation sources was measured to provide standards for comparison. Once a basis of effective shielding was established, the study can go into greater depth into how to use shielding materials to be more effective, to better shield …

For The Dissertation: A Classification Of Tensors In Ecsk Theory, Joshua James Leiter, Charles G. Torre

Physics Student Research

This dissertation presents a Petrov/Plebanski/Segre/Algebraic (PPSA) classification scheme for both the curvature and torsion tensors in Einstein-Cartan-Sciama-Kibble theory (ECSK); additionally the work includes a software package in Maple with computational and PPSA classification tools. Six different solutions are classified using the new software tools developed. We also present a new boundary term for ECSK-NMC scalar theory to ensure Dirichlet boundary conditions. New work completed includes the decomposition of an arbitrary 4th rank tensor under SO (p, q), equivalent SL (2, C) irreducible spinor decompositions of arbitrary 3rd and 4th rank tensors. We provide new proofs that the corresponding spinors are …

Mesopause Region Temperature And Na Number Density Between 1990 And 2017, Tao Yuan, Chiao-Yao She

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The Colorado State University (CSU) Na lidar performed nocturnal mesopause region Na density and temperature observations between March 1990 and March 2010 at Fort Collins, CO (41.6N, 105W). The lidar was relocated to Utah State University (USU) campus and has continued its regular observation at Logan, Utah (42N, 112W) since September 2010.

Relevancy Of Pulsed Electroacoustic Measurements For Investigating Spacecraft Charging, Zachary Gibson, J. R. Dennison

Journal Articles

The magnitude and spatial distribution of charge embedded in dielectric materials and the evolution of the charge distributions with time are paramount for the understanding and mitigation of spacecraft charging. Spacecraft materials are charged primarily by incident fluxes of low-energy electrons, with electron fluxes in the 10–50 keV range often responsible for the most deleterious arcing effects. While the pulsed electroacoustic (PEA) method can provide sensitive nondestructive measurements of the internal charge distribution in insulating materials, it has often been limited for spacecraft charging applications by typical spatial resolutions of ≤ 10 μm , with a 10- μm …

Space Environment Effects On The Electron Yields Of Ldef Thermal Control Coatings, Trace Taylor, Matthew Robertson, Heather Allen, Jr Dennison, Michael Guy, Emily Willis

Journal Articles

Space-environment-induced degradation of white thermal control coatings from the Long Duration Exposure Facility (LDEF) was investigated. Much of the exterior of the LDEF was painted with a white thermal control coating, Aeroglaze A276; and most of the interior was coated with a black thermal control coating, Aeroglaze Z306. Outgassing from these coatings and other LDEF materials interacted with the white surface when exposed to sunlight after volatile materials condensed on the LDEF surfaces. Surface morphology was characterized by optical and scanning electron microscopies. Fourier-transform infrared spectroscopy and energy-dispersive x-ray spectroscopy were used to identify the chemical compounds and elements present …

Comparison Of Pulsed Electroacoustic Measurements And Af-Numit3 Modeling Of Polymers Irradiated With Monoenergetic Electrons, Zachary Gibson, J. R. Dennison, Brian Beecken, Ryan Hoffmann

Journal Articles

Successful spacecraft design and charging mitigation techniques require precise and accurate knowledge of charge deposition profiles. This paper compares models of charge deposition and transport using a venerable deep dielectric charging code, AF-NUMIT3, with direct measurements of charge profiles via pulsed electroacoustic (PEA) measurements. Eight different simulations were performed for comparison to PEA experiments of samples irradiated by 50 or 80 keV monoenergetic electrons in vacuum and at room temperature. Two materials, polyether-ether ketone (PEEK) and polytetrafluoroethylene (PTFE), were chosen for their very low conductivities so that minimal charge migration would occur between irradiation and PEA measurements. PEEK was found …

Characterizing The Charging Properties Of Lunar Dust Is Critical To Returning To The Moon, Heather Allen

Research on Capitol Hill

Reliable electron yield (EY) measurements of highly insulating granular particles have long been considered too difficult to collect due the many experimental complexities that arise from the nature of the granular materials. This has led to a critical knowledge gap for both engineering strategies and basic science issues essential for myriad important space applications. This talk will emphasize the preliminary EY measurements of highly insulating granular samples we have collected, including a range of sasmples with typical particle size ranging from ~1 μm to ~100 μm, samples with cubical, spherical and highly angular particle shapes, studies of highly angular Al2O3 …

Grinding Cocoa Changes Chocolate Properties, Joseph Cooney

Research on Capitol Hill

This research studies how the viscoelastic properties of chocolate change through the 72-hour grinding process of chocolate manufacturing. Utah State University's Aggie Chocolate Factory produces chocolate from single-origin sources, each of which has a unique flavor, and thus a unique chemistry. This research explores the effects of grinding time on the viscoelasticity of each of these origins' chocolate types, including dark, sweet dark chocolate, and milk chocolate. Chocolate is a non-Newtonian fluid and therefore the Casson model (eq. 1) was used to obtain values for viscosity and yield stress, τ^(1/2)=τ_0^(1/2)+(η_PL y' )^(1/2) (1) Where τ is the shear stress measured …

Foundations Of Wave Phenomena: Complete Version, Charles G. Torre

Foundations of Wave Phenomena

This is the complete version of Foundations of Wave Phenomena. Version 8.3.1.

Please click here to explore the components of this work.

Effects Of Exposure To Atmospheric Humidity On Breakdown Field Strength Measurements Of Polymers, Megan Loveland Dewaal

Physics Capstone Projects

This study investigates the effects of absorbed water introduced via exposure to atmospheric humidity on electrostatic breakdown field strength measurements of polymers. Conducting breakdown tests under sample conditions appropriate for different applications is essential. If the breakdown field strength is overestimated for an application, an insulator may be used inappropriately in high electric fields where they are more likely to break down. Comparisons are made between: sets of pristine samples, samples that underwent a thorough vacuum bake out to remove absorbed water, and samples subject to subsequent incremental prolonged atmospheric exposure. These investigated the effects of absorbed water and determined …

Spacecraft Charging Test Considerations For Composite Materials, Allen Andersen, Wousik Kim, J. R. Dennison, Brian Wood, Todd A. Schneider, Jason Vaughn, Kenneth H. Wright Jr., Nelson W. Green, Eric Suh, Joel Schwartz, Abdul-Majeed Azad

Journal Articles

Composite materials present a growing challenge for spacecraft charging assessments. We review some recent lessons learned for charging tests of composite materials using both parallel-plate and electron beam test geometries. We also discuss examples of materials that exhibit significant variations between samples, despite them all having the same trade name.

A Study Of Electron Plasma Oscillations Using The Nimrod Code, Mckay Murphy

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

A plasma, whether ”hot” or ”cold,” magnetized or unmagnetized, electrostatic or electromagnetic, exhibits normal modes of oscillation. Critical to understanding the stability of a plasma is the study of these normal modes. Waves originate from the long-range electric interactions between charged particles. This work will consider a class of waves known as Langmuir waves. These waves occur when a group of electrons are displaced with respect to the ions, with the electric Coulomb force playing the role of the restoring force of the oscillation [1]. Since the mass of ions is much greater than that of electrons, we can approximate …

Bifurcations And Hysteresis In The Dynamics Of Small Populations Of Spherical Magnets, Peter T. Haugen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

If you heat up some kinds of metals and then cool them down next to a magnet, they will be a magnet when they cool, but if they cool down away from a magnet, they will just be a lump of metal. This is an example of hysteresis and it’s very important for lots of technology. Another example of hysteresis might be a water tower pump that turns on when the tower is nearly empty and keeps going until the tower is nearly full. Whether or not the pump is on when the tower is half full depends on what …