Physics Commons^™

Scattering Of Light From Periodic Conducting Nanostructures, Wesley Mills

Fall Student Research Symposium 2021

Light scattered from periodic structures generates numerous fascinating phenomena, from diffraction patterns to the black patches on some butterfly wings. The simple scalar wave formulation based on Huygens principle can account for many diffraction and radiation patterns in the far field. However, when the structure dimensions are smaller than the wavelength, light polarization and structure details become important, and the vector formulation based on Maxwell's equations is necessary. I will present an analytic calculation and a numerical simulation on light scattering from two-dimensional conducting grids to model the reflectance from butterfly wings and broadband absorption structures made from carbon nanotube …

Equivalence: A Covariantly Constant Problem In General Relativity, Jaren Hobbs

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

In studying the space-time structures described by Einstein’s theory of general relativity, it is often useful to identify particular properties referred to as geometrical invariants. These are attributes of the space-times which do not change regardless of the underlying coordinate systems used to study them. This project is part of a larger effort to catalogue space-times studied in general relativity. Specifically, computational software was used to identify structures known as covariantly constant vector fields.

Absolute Neutral Densities And Temperatures And Their Climatologies In The Middle Atmosphere Using An Optimal Estimation Method With Rayleigh-Scatter Lidar Observations Obtained At Utah State University, Jonathan L. Price

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Earth’s atmosphere is comprised of layers which can be defined by their temperature characteristics. These layers are the troposphere, stratosphere, mesosphere and thermosphere. The region where life exists is in the troposphere, however the study of the layers above is important as changes in these regions can directly impact, or indicate significant changes in, weather in the troposphere. The mesosphere is the least well-known region because it is the most difficult to observe. One of the best tools for observing this region is the Rayleigh-scatter lidar. It is capable of remotely observing the entirety of the mesosphere with good …

The Internal Charge Evolution Of Multilayered Materials Undergoing Mono-Energetic Electron Bombardment, Gregory Wilson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The charging of multilayer materials as related to the charging of spacecraft is one of the primary concerns related to activities in the space environment. To understand how multilayer materials undergoing electron bombardment charge, an in-depth study of energy-dependent material properties must be undertaken. These properties include the electron penetration depth, secondary electron emission, charge transport and electrostatic discharge. By using energy dependent models of these properties, along with the geometry of the system, multilayer models can be developed to predict the time evolution of the internal charge distribution. Using these models, the net surface potential and the measurement of …

Geometrization Of Perfect Fluids, Scalar Fields, And (2+1)-Dimensional Electromagnetic Fields, Dionisios Sotirios Krongos

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Rainich equations provide a purely geometrical interpretation of matter in terms of the gravitational field it generates. All this takes place within the geometrical formulation of gravity provided by Einstein’s General Theory of Relativity. Rainich-type conditions giving spacetime "goemetrizations" are reviewed and extended. Three types of matter are considered: perfect fluids, scalar fields, and electromagnetic fields.

Charge Transport In Dielectric: The Pulsed Electroacoustic Method, Zachary Gibson

Physics Student Research

Understanding and predicting charge accumulation and transport in dielectric materials is vital in applications where excess charge can accumulate including semiconductor devices, high-power electronic devices, high voltage DC cabling, high-energy physics facilities, plasma chambers, and spacecraft charging. Excess charge accumulation may result in electrostatic discharge events, which are the leading cause of spacecraft failure due to the space environment. The pulsed electroacoustic method allows you to “pop the hood” and non-destructively directly measure the embedded charge distributions in dielectric materials. Charge transport in disordered dielectric materials, measurements with the pulsed electroacoustic system, and comparison to models will be presented.

Geodetic Model For Teaching Motion On The Earth's Spheroidal Surface, Boyd F. Edwards, John M. Edwards

All Physics Faculty Publications

We explore the forces that shape our spheroidal Earth and the forces that govern the motion of a puck that slides without friction on its surface. The Earth's stable spheroidal shape (apart from small-scale surface features) is determined by balancing the gravitational forces that hold it together against the centrifugal forces that try to tear it apart. The motion of a puck on its surface differs profoundly from motion on a sphere because the Earth's spheroidal deformations neutralize the centrifugal and gravitational forces on the puck, leaving only the Coriolis force to govern the motion. Yet the Earth's spheroidal deformations …

Comparison Of Charge Deposition Profiles In Polymers Irradiated With Monoenergetic Electrons: Pulsed Electroacoustic Measurements And Af-Numit3 Modeling, Zachary Gibson, Jr Dennison, Brian Beecken

Physics Student Research

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 keV 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 …

Embedded Charge Distributions In Electron Irradiated Polymers – Pulsed Electroacoustic Method Reproducibility And Calibration, Zachary Gibson, Jr Dennison, Ryan Hoffmann

Physics Student Research

The pulsed electroacoustic (PEA) method has been used to measure the embedded charge distributions in electron irradiated polymers. The PEA method allows for non-destructive direct measurements of embedded charge distributions in dielectric materials. Samples of polyether-etherketone (PEEK) and polytetrafluoroethylene (PTFE) of 125 μm or 250 μm thickness were tested after irradiation with either a 50 keV or 80 keV electron beam. The reproducibility of the PEA method and the experimental conditions were studied by: (i) measuring each sample multiple times in a given mounting configuration, (ii) re-measuring each sample after repositioning them in the PEA test fixture, and (iii) measuring …

Pan-Antarctic Investigations Of Mesospheric Wave Dynamics And Influences Using The Angwin Network, Michael J. Taylor

Funded Research Records

No abstract provided.

Forces And Conservation Laws For Motion On Our Spheroidal Earth, Boyd F. Edwards, John M. Edwards

All Physics Faculty Publications

We explore the forces and conservation laws that govern the motion of a hockey puck that slides without friction on a smooth, rotating, self-gravitating spheroid. The earth's oblate spheroidal shape (apart from small-scale surface features) is determined by balancing the gravitational forces that hold it together against the centrifugal forces that try to tear it apart. The earth achieves this shape when the apparent gravitational force on the puck, defined as the vector sum of the gravitational and centrifugal forces, is perpendicular to the earth's surface at every point on the surface. Thus, the earth's spheroidal deformations neutralize the centrifugal …

Temperature Tides Across The Mid-Latitude Summer Turbopause Measured By A Sodium Lidar And Mighti/Icon, Tao Yuan, M. H. Stevens, C. R. Englert, T. J. Immel

All Physics Faculty Publications

Local full diurnal coverage of temperature variations across the turbopause (∼90–115 km altitude) is achieved by combining the nocturnal observations of a Sodium (Na) Doppler lidar on the Utah State University (USU) campus (41.7°N, 248.2°E) and NASA Michelson interferometer for global high-resolution thermospheric imaging (MIGHTI)/Ionospheric connection explorer (ICON) daytime observations made in the same vicinity. In this study, utilizing this hybrid data set during summer 2020 between June 12th and July 15th, we retrieve the temperature signatures of diurnal and semidiurnal tides in this region. The tidal amplitudes of both components have similar vertical variation with increasing altitude: less than …

Computational Frontiers In The Strong Gravity Regime, Maria Rodriguez

Funded Research Records

No abstract provided.

Benchmarking Nimrod Continuum Kinetic Formulations Through The Steady-State Poloidal Flow, Joseph R. Jepson, Chris C. Hegna, Eric D. Held, J. Andrew Spencer, B. C. Lyons

All Physics Faculty Publications

In this work, continuum kinetic formulations are employed as a mechanism to include closure physics in an extended magnetohydrodynamics model. Two continuum kinetic approaches have been implemented in the plasma fluid code NIMROD [Sovinec et al., “Nonlinear magnetohydrodynamics with high-order finite elements,” J. Comput. Phys. 195, 355 (2004)] including a Chapman–Enskog-like (CEL) formulation and a more conventional δf approach. Ion kinetic closure schemes are employed to describe the neoclassical flow properties in axisymmetric toroidal geometry. In particular, predictions for steady-state values of poloidal flow profiles in tokamak geometry are provided using both the δf formulation and two different solution …

Electron Yield Decay Curves For Analysis Of Sample Charging And Neutralization, Matthew Robertson

Utah Space Grant Consortium

Excess charge on a material will affect the electron yield of the material. Electron yield is an attribute of materials which describe how the material behaves when irradiated with electrons. It is the ratio of the number of electrons going into the material over the number of electrons leaving the material. Understanding how a sample charges is important in both how it affects the electron yield and how it can be neutralized.

Comparing P-11b To D-3he Fusion For Direct Drive Fusion Rockets, Christopher Hooper

Utah Space Grant Consortium

Direct Fusion Drive (DFD) is a theoretical configuration that uses a magnetically confined fusing plasma to provide thrust for a rocket. In the words of the original authors, Princeton Satellite Systems (PSS) and Razinet al., it is “...a compact, anuetronic fusion engine [which] will enable more challenging exploration missions in the solar system.” DFD is proposed as a theoretical alternative to chemical and ion propulsion rockets – as seen in Table 1, it has clear advantages over both in exhaust velocity (specific impulse) and mass ratio, and a large advantage over ion propulsion in thrust and thrust-to-weight ratio. Despite being …

A Study Of Oxidation In Thin-Film Uranium-Niobium Alloys, Logan C. Page

Utah Space Grant Consortium

Uranium, a nuclear fuel material, can oxidize and degrade in reactor conditions. Previous studies have shown oxidation resistance in a uranium-niobium alloy, U-6Nb (six weight percent niobium in uranium). The nature of the oxides that form on sputtered U-6Nb thin films after long exposure to air was previously explored using neutron diffraction at Los Alamos National Laboratory. In the present work, we deposited thin films of uranium-niobium alloys for oxidation studies. We used ellipsometry to quantify the oxide growth over time as a function of niobium content. We found that the oxide thickness increases linearly with the logarithmic of time. …

Comparison Of Rayleigh-Scatter Lidar Temperature Climatologies In The Mesosphere And Lower Thermosphere Between The Traditional Reduction Method And The New Optimal Estimation Method, Jonathan Price

Utah Space Grant Consortium

An optimal estimation method (OEM) was used to obtain all-night temperature profiles from Rayleigh-scatter lidar (RSL) observations obtained by the original and updated lidar systems at Utah State University (USU). These data were used to produce annual climatologies of temperatures above USU. The climatology of temperatures from the original lidar, which operated from late 1993 through 2004, was compared with the climatology produced using the widely used Hauchecorne-Chanin method (HC). This comparison highlights the similarities at lower altitudes and differences, which start between 70 km and 80 km and extend to the top altitudes with the OEM temperatures warmer on …

Seeking The Origin Of Electromagnetic Signatures Of Black Holes, Alexandra B. Chanson

Utah Space Grant Consortium

Relativistic-jet formation in astrophysical black holes lacks a rigorously understood mechanism of energy extraction in the high-energy regime although, in recent years, progress has been made in extending the non-linear equations of Force-Free Electrodynamics (FFE) into the high-spin regime. In particular, M. J. Rodriguez and A. Strominger were able to show, using the Near Horizon Extremal Kerr spacetime, that the near horizon FFE solutions have an additional scaling symmetry which allows the construction of a pseudo-analytical infinite tower of solutions. These families of solutions stand in stark contrast to the relatively few full Kerr solutions found analytically: this tension can …

Phase-Space Dynamics Of Runaway Electrons In Tokamaks, Gavin Held

Physics Capstone Projects

Nuclear fusion converts the rest mass energy of ions like the deuteron and triton into kinetic energy. In theory, this energy can be harvested from a thermonuclear reactor to provide power outputs on the scale of 500 MW. High temperatures are needed for significant fusion to occur, hence the tokamak (a modern fusion confinement device) employs strong magnetic fields to keep the ionized gas (plasma) away from the tokamak wall. However, a problem that occasionally arises in a tokamak is that during a disruption an inductive electric field is created which can accelerate electrons to relativistic speeds (these electrons are …

Comparisons Of Mesospheric Temperatures Between 70 And 110 Km: Usu Lidar, Nasa's Timed Satellite, And The Msis2 Empirical Model, David M. Collins

Physics Capstone Projects

Earth’s atmosphere can be characterized by its temperature structure, dividing the atmosphere into natural discrete regions. The mesosphere (50 to ~100 km) has been the least studied. Rayleigh-scatter lidars (RSL) and rockets can obtain local, high-resolution measurements above one spot, while satellites looking almost horizontally obtain global measurements. These two methods of measuring atmospheric conditions are compared using the USU RSL and the SABER instrument on NASA’s TIMED satellite. These measurements were graphed to show four sets of temperatures from several sources in the atmospheric region 70 km to 110 km above USU. The results show similar temperatures for many …

Fundamental Aspects Of Black Holes, Jacob Fisher Ciafre

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

The literature study here seeks to present the foundations of black hole physics in General Relativity. The report includes a discussion of the Kerr black hole metric, black hole entropy, particle creation, the laws of black hole mechanics, and a bilinear mass formula for the Kerr-Newman black hole solution.

Developing Electron Beam Lithography At Nanoscale Device Laboratory, Din Pašić

Physics Capstone Projects

At the Nanoscale Device Laboratory, we can routinely create patterns with a minimum linewidth of 800 nm using photolithography. However, to create photonic devices, the pattern size must be smaller than the wavelength of visible light (400 to 800 nm). Dedicated electron beam writers can achieve a sub-10 nm linewidth, but this system is beyond our reach. In this project, we plan to use a Nanometer Pattern Generation System connected to a Quanta 650 scanning electron microscope to perform e-beam lithography. After setting up a computer to run the NPGS system, and establishing communications with the SEM, we experimented with …

The Effects Of Materials And Profiles Of Gratings On Diffraction Spectra, Brock Halling

Physics Capstone Projects

Diffraction patterns can be made either by transmitting or reflecting light from a grating which is an array of parallel lines (rulings) with a fixed periodicity. Elementary optical treatment of diffraction gratings only describes diffraction angles as a function of periodicity of the grating. However, we have observed that the profile and materials of the grating do affect the diffraction pattern. In this study, I investigated the correlation between the grating profiles obtained by scanning electron microscopy and the materials of the grating (polymer and silicon dioxide) and the spectra as a function of the diffraction angle. An optical spectrometer …

The Reflection Of Light From Periodic Conducting Interfaces, Christian Lange

Undergraduate Honors Capstone Projects

It is known that carbon-nanotube (CNT) forests, nanopillar arrays, and other high aspect-ratio conducting and semi-conducting nanostructures can have extremely low reflectance in a wide range of wavelengths, and that reflectance begins to rise at long wavelengths. The mechanism for this behavior is poorly understood. It has been shown that the reflectance of CNT forest varies with the morphology of the forest, which indicates that the interface of such a material may play a primary role in its reflectance and absorptance.

Simulations of the reflection of light from arrays of conducting nanorods using commercial finite-difference-time-domain software predict a similar increase …

Improving Skills In Computer Methods: Introductory Toolkit To Python For Undergraduate Physics Majors, Erin O'Donnell, Melissa Rasmussen

Physics Capstone Projects

The computer-based curriculum for undergraduate physics students before 2019 struggled to stay current and applicable. When the course was created in the early 2000s, MathCad was used daily by many physicists. As computer’s and their computational abilities have grown exponentially, so have programming languages and applications. Now in the late 2010s/early 2020s, Excel, Python, and Mathematica are some of the most common computer appliques. To address this, we created toolkits to give undergraduate physicists the experience for future classes, careers, and graduate school. This paper focuses on the process for creating the Python toolkit and overall class setup. Run on …

Ion Beam-Treated Space Polymers: Long-Term Stability In Geo-Simulated Environments, Jacob Kleiman, Zelina Iskanderova, Leonid Krishtein, J. R. Dennison, Brian Wood, Anatoly Grigorievsky, Carl Best

Journal Articles

As part of a large program conducted between years 2010 and 2018, a number of ion beam surface treatments and proprietary coatings formed on advanced space polymers by direct ion beam deposition were developed at Integrity Testing Laboratory (ITL) Inc, in Canada. Thistechnology allowed producing surfaces with controlled surface resistivity in a wide range of charge dissipation values, with negligibly low additional RF losses and other important functional properties, that allowed using such treated materials and products in modern space antennae, solar arrays and other external applications on spacecrafts in GEO environment. This paper will present an overview of results …

Rapid: Sodium (Na) Lidar Validation Of Mighti Daytime Temperature Observations Onboard Nasa Icon Satellite, Tao Yuan

Funded Research Records

No abstract provided.

Potential, Field, And Interactions Of Multipole Spheres: Coated Spherical Magnets, Jeong-Young Ji, Boyd F. Edwards, J. Andrew Spencer, Eric D. Held

All Physics Faculty Publications

We show that the energy, force, and torque between two spherically symmetric multipole density distributions are identical to those between two point multipoles, and apply this point-sphere equivalence to coated spherical dipole magnets. We also show that the potential and field of such a distribution are equivalent to those due to point multipoles located at the center of the distribution. We expand the inverse-distance potential in terms of harmonic (Hermite irreducible) tensors, whose properties enable us to express the potential energy, force, and torque for two arbitrary source distributions in a series of point-multipole interactions. This work generalizes recent work …

Na Lidar And Mighti/Icon Investigation On Turbopause Tidal Waves, Tao Yuan, Michael H. Stevens, Christoph R. Englert, Thomas J. Immel

Browse all Datasets

Local full diurnal coverage of temperature variations across the turbopause (~ 90 km to 115 km altitude) is achieved by combining the nocturnal observations of a Sodium (Na) Doppler lidar on the Utah State University (USU) campus (41.7?N, 248.2?E) and NASA MIGHTI/ICON daytime observations made in the same vicinity. In this paper, utilizing this hybrid dataset during summer 2020 between June 12th and July 15th, we retrieve the temperature signatures of diurnal and semidiurnal tidal waves in this region. The tidal amplitudes are similar for both components: less than 5 K below ~ 98 km but increase considerably above, up …