Physics Commons^™

Electron-Phonon Coupling In Copper, Joseph Pigott

Student Research Symposium

The behavior of metals is all about the motion and behavior of the metal's electrons. When interactions between the electrons and vibrations in the crystal lattice (phonons) are considered, the electrons act as if they are "heavier" than they otherwise would be. This is accounted for by introducing the mass- enhancement parameter λ, which represents the strength of electron- phonon interactions. This study explores whether λ can be accurately calculated by comparing literature data for two known quantities: the electronic coefficient of specific heat and the density of states at the Fermi energy.

Ion-Induced Electron Yield Database Development Through Data Mining For Exploratory Data Analysis And Predictive Analytics, Trace Taylor

Student Research Symposium

• What is ion yield and what affects it?

• Why create a database?

• Status of the database

• Ion yield data comparisons

• Conclusions

• Future work

Are Rotating Black Holes Rigid?, Luis Fernando Temoche

Student Research Symposium

What is rigidity for a black hole?

Gravity Wave Activity During The 2024 Sudden Stratospheric Warmings Observed By Atmospheric Waves Experiment (Awe), Jiarong Zhang, Yucheng Zhao, Pierre‐Dominique Pautet, Ludger Scherliess, Michael J. Taylor, Hanli Liu

All Physics Faculty Publications

The National Aeronautics and Space Administration (NASA) Atmospheric Waves Experiment (AWE) instrument, launched in November 2023, provides direct observation of small‐scale (30–300 km) gravity waves (GWs) in the mesosphere on a global scale. This work examined changes in GW activity observed by AWE during two major Sudden Stratospheric Warmings (SSWs) in the 2023 and 2024 winter season. Northern Hemisphere (NH) midlatitude GW activity during these events shared similarities. Variations in mesospheric GW activity showed an evident correlation with the magnitude of zonal wind in the upper stratosphere. NH midlatitude GW activity at ∼87 km was reduced following the onset of …

Mitigation Of Lunar Dust Charging Issues Using Electron Yield, Christopher Vega

Student Research Symposium

What is Electron Yield?

• Electron Yield(EY): Ratio of electrons in over electrons out

Physical Interpretation Of The Dynamic Dual-Defect Model Of Radiation Induced Conductivity, Tyler Heggenes, Jenny Whiteley

Student Research Symposium

• Spacecraft charging is the main source of spacecraft anomalies [A]
• Spacecraft are often made of resistors
• Arcing can end a project early

Fiber Bundles Of The Complex Projective Space And Their Relation To Quantum Physics, Emily Wessman

Student Research Symposium

The complex projective space CPⁿ is the space of lines through the origin in Cⁿ⁺¹ with an equivalence relation defined by Z ~ λZ' for λ ∈ C*. We define the points under the equivalence relation as homogeneous coordinates, represented by [Z₀ : Z₁ : ... Z_n]. Since all Z,sub>i cannot equal zero, we can find a unique set of n coordinates (z₁,...,z_n) such that [Z₀ : Z₁ : ... : Z_n] ~ [1 : z₁ : ... : z_n] where z …

Synthesis Of Pristine Graphene On Cu Substrates Within A 3d Parameter Space, Max Haehnel

Student Research Symposium

We designed a low-pressure chemical vapor deposition system wherein the toluene combines with the carrier gas flow to contact with the substrate within the quartz tube. As toluene is a liquid at room temperature, we froze the toluene using liquid nitrogen before pumping down the chamber to low pressure. Substrate cleanliness and preparation proved to be essential in the synthesis process.

Evidence Of Substorm-Driven Penetration Electric Field Contributions To Low-Latitude Phenomena: Enhanced Upward Drifts, Plasma Bubble Development And Severe Scintillation, J. Sousasantos, F. S. Rodrigues, B. G. Fejer, R. W. Eastes, A. O. Moraes

All Physics Faculty Publications

In this work, it is demonstrated that substorm-driven penetration electric fields can efficiently enhance the upward plasma transport, favoring the development and structuring of plasma irregularities and the occurrence of scintillation on L-band signals. While most previous studies focus on investigating penetration electric fields during intense geomagnetic storms, here, the period used (April 01–05, 2020) was under very mild geomagnetic activity (−27 nT ≤ SYM-H ≤ 6 nT), so that interplanetary and disturbance dynamo contributions are minimized. This period comprised the same seasonal and solar flux conditions, while undergoing multiple short-lived substorms, making it well-suited to evaluate unequivocally: (a) to …

Demonstration Of Real-Time Precision Optical Time Synchronization In A True Three-Node Architecture, Kyle W. Martin, Nader Zaki, Nolan Matthews, Matthew S. Bigelow, Benjamin K. Stuhl, John D. Elgin, Kimberly Frey

Space Dynamics Laboratory Publications

Multi-node optical clock networks will enable future studies of fundamental physics and enable applications in quantum and classical communications as well as navigation and geodesy. We implement the first ever multi-node optical clock network with real-time, relative synchronization over free-space communication channels and precision on the order of 10 femtoseconds, realized as a three-node system in a hub-and-spoke topology. In this paper we describe the system and its performance, including a first ever measurement of precision optical time synchronization between nodes with no direct communication link or causal feedback relationship.

Infrared Sensors Provide A Reliable And Economic Alternative For Emissivity Testing, Owen Brent Graham

Research on Capitol Hill

Emissivity is a material property that describes how well a material absorbs and emits electromagnetic radiation.

Impact Of Arctic And Antarctic Sudden Stratospheric Warmings On Thermospheric Composition, Jiarong Zhang, Jens Oberheide, Nicholas M. Pedatella, Guiping Liu

All Physics Faculty Publications

Using the Global‐scale Observations of the Limb and Disk (GOLD) and the Global Ultraviolet Imager (GUVI), we examine the impact of sudden stratospheric warmings (SSWs) on the changes of thermospheric composition during the 2018–2019 and 2020–2021 Arctic SSWs and the 2019 Antarctic SSW. Contributions of planetary waves, gravity waves, and migrating tides are assessed by performing numerical experiments with the NSF National Center for Atmospheric Research (NCAR) vertically extended version of the Whole Atmosphere Community Climate Model (WACCM‐X). The variations in the column integrated O and N2 density ratio (∑ O/N₂) are generally similar among WACCM‐X, GOLD, …

Constructing And Testing Of Photomultiplier Tubes For Coincidence Experiments, Christepher Zamora

Physics Capstone Projects

Muons are particles that can be created by the collision and decay of cosmic rays with the upper atmosphere. Many detectors have been manufactured to detect these particles. This paper describes how muons can be detected. It details the process of constructing and testing of scintillation photomultiplier tubes. This paper also details what was observed during the construction and what was done by the experimenter to correct perceived issues.

Analysis Of A Gravity Wave Horizontal Blocking Event Using Hodograph Techniques Applied To Sodium Lidar Data, Neal R. Criddle

All Graduate Theses and Dissertations, Fall 2023 to Present

Atmospheric gravity waves are ubiquitous and important events in Earth’s atmosphere with impacts on space weather and associated technological effects. The population of gravity waves is determined by their formation mechanisms, and their interactions with the background atmosphere. These gravity waves transport energy and momentum into the near Earth space environment, and are responsible for movement of chemical species. Predicting the occurrence of space weather effects, then, is in part a process requiring the characterization of gravity waves. Case studies of unique and interesting gravity wave events are an important part of this process. These allow for the investigation of …

The Temperature Trend In The Upper Mesosphere Between ∼84 Km And 98 Km Based On Diurnal Cycle Observations By A Na Lidar At Middle Latitudes Between 2002 And 2017, Melania Carolina Pena

All Graduate Theses and Dissertations, Fall 2023 to Present

Carbon dioxide is one of the main greenhouse gasses that contributes to maintaining Earth’s warm global temperature in its atmosphere. Recent studies have indicated that this cooling trend has been determined to vary between less than 1 K/decade or 2 K/decade. However, these results have been determined using data that have been obtained using nighttime lidar observations and potentially do not give the complete picture on how the cooling trend is behaving. The main goal of this research is to understand the behavior of the linear temperature trend between the daytime and nighttime profiles using a 16-year dataset (2002-2017), when …

Modeling Permittivity Measurements Of Thin Film Materials Versus Film Thickness, Jr Dennison, Cameron Eggleston

Journal Articles

Measured permittivity of thin film polymeric samples were substantially less for thin samples, asymptotically approaching bulk values above ~500 μm. For ~25 μm samples the observed permittivities were as much as 50% less than for bulk measurements. This behavior has been studied for four common homogeneous polymeric materials for sample thickness in the range of ~10 μm to > 1000 μm. To quantify these observations, an empirical single-parameter model was developed to correct measured permittivity of thin samples based on an effective stray capacitance in series with the samples to compensate for effects attributed to instrumentation.

Implementing General Moment Equations For Parallel Closures In Nimrod, Hankyu Lee

All Graduate Theses and Dissertations, Fall 2023 to Present

Understanding how magnetic fields impact plasma transport is essential for improving the efficiency of thermonuclear fusion power plants. To address the transport problem, both plasma fluid equations and Maxwell’s equations must be solved. To solve these equations, it is necessary to derive closure relations that allow the system to be closed. Previous closure models are useful for describing the behavior of high-collisionality plasma but are not effective at low collisionality. To obtain closure relations valid for low collisionality, the first-order drift kinetic equation must be solved.

This study presents methods for numerically obtaining parallel closures for NIMROD code by deriving …

Md Simulations Of Collision Effects For A Strongly Coupled Plasma, Jawon Jo

All Graduate Theses and Dissertations, Fall 2023 to Present

Studying strongly coupled plasmas can be effectively accomplished using molecular dynamics (MD) simulations. We have developed an advanced MD simulation code that can analyze plasmas with various coupling parameters. This code employs a spherically symmetric cut-off Coulomb force verified through convergence tests by modulating the cut-off and minimum force ranges. Additionally, it incorporates a new algorithm for optimizing the initial positions of particles at a given temperature. This method maintains the temperature constant and the velocity distribution unchanged. As a result, we eliminate the unphysical initial rises and oscillations in temperature that a random distribution of positions causes. The code …

Effects Of Differing Radiation Methods On Charge Transport In Polymers, Zachary Gibson, Jr Dennison, Virginie Griseri

Presentations

The mitigation of deleterious arcing and sparking onboard spacecraft depends upon a thorough understanding of the electrical properties of the materials involved. This includes not only understanding steady-state parameters such as dark conductivity, but responses to the space environment as well. For example, radiation-induced conductivity drastically changes the conductivity of a material due to the presence of radiation. However, this change in conductivity diminishes away once the radiation is no longer present. There may also be permanent changes, or aging, in the material properties. The physical processes of aging can be complicated and are often difficult to model. Therefore, empirical …

Radiation Induced Conductivity Of Peek: Effects Of Temperature And Total Ionizing Dose, Joshua Boman, Brian Wood, Jordan Lee, Jr Dennison, Kim M. Aaron, Wousik Kim

Conference Proceedings

Radiation induced conductivity (RIC) plays a critical role in space charge dissipation with insulating materials used in spacecraft. Ionizing radiation present in harsh space plasma environments deposits energy into materials via inelastic scatter, exciting electrons into the conduction band without depositing charge for penetration radiation. RIC is expected to be affected by temperature and total ionizing dose (TID); temperature primarily affects the rate of promotion of electrons in localized trap states within the band gap to the conduction band, while TID can create additional traps states thereby increasing trap density and reducing mean trap separation.

RIC was measured in a …

Temperature Dependent Radiation Induced Conductivity Of Polymeric Spacecraft Materials, Jodie Corbridge Gillespie, Jr Dennison

Conference Proceedings

Temperature dependent radiation induced conductivity (RIC) data applicable to conditions experienced by spacecraft are presented for low density polyethylene (LDPE) and poylimide (PI, Kapton^HN, along with summaries for five other common polymeric spacecraft mateials: polyimide (PI; Kapton HN^TM, and Kapton E^TM), polytetraflouroethylene (PTFE; Teflon^TM), expanded PTFE (ePTFE), ethylene-tetrafluoroethylene and (ETFE; Tefzel^TM). Data were measured over approximately 105 K to 330 K and incident dose rates, D, of 10^-4 Gy/s to 10^-1Gy/s. Theoretical expressions proposed by Rose/Fowler/Vissenberg predict equilibrium RIC behavior according to a general expression σ …

Time-Dependent Behavior Of Radiation Induced Conductivity In Polymers, Tyler Heggenes, Jenny R. Whiteley, Jodie Corbridge Gillespie, Joshua Boman, Jr Dennison

Conference Proceedings

Ionizing radiation can induce conductivity in polymers via inelastic scattering which imparts energy to electrons in the valence band and trapped states, exciting them into the conduction band without depositing charge into the material. This radiation-induced conductivity (RIC) can impact space charge dissipation within highly insulating materials used in spacecraft in harsh space plasma environments. Previous USU research analyzed only the equilibrium portions of an extensive RIC database for polymeric materials, including Kapton HN^TM. This confirmed that equilibrium RIC follows a standard theoretical model that is temperature and dose-dependent. The current study provides a new analysis of RIC's …

Comparison Of Absolute Electron Emission Yields Of Extreme Insulators: Round Robin Tests Of Polyimide And Low Density Polyethylene, Jr Dennison, Matthew Robertson, Christopher Vega, Mohamed Belhaj, Juste Sarah Dadouch, Isabel Montero, María E. Dávila, Kazuhiro Toyoda

Posters

No abstract provided.

Temperature Dependent Radiation Induced Conductivity Of Polymeric Spacecraft Materials, Jodie Corbridge Gillespie, Jr Dennison

Posters

No abstract provided.

Analysis Of The Effects Of Surface Modifications And Other Extrinsic Factors On Electron Yield With A “Patch” Model, Matthew Robertson, Christopher Vega, Trace Taylor, Jr Dennison

Presentations

Electron yield (EY) is a material attribute of central importance to understanding and modeling spacecraft charging. EY is defined as the ratio of emitted electrons to incident electrons, when irradiated with an electron beam. It depends on incident energy and is unique for each material as determined by its chemical composition, crystal structure, and electronic configurations. Dynamic surface modifications and other extrinsic factors—including surface morphology, composition, contamination, oxidation, and charging— can significantly affect EY and consequently spacecraft charging. This research proposes a “patch” model to provide a simple theoretical framework to model more complex materials comprised of any number of …

Time-Dependent Behavior Of Radiation Induced Conductivity Of Polymers, Tyler Heggenes, Jenny R. Whiteley, Jodie Corbridge Gillespie, Joshua Boman, Jr Dennison

Presentations

The conductivity of insulating materials can be enhanced above the baseline dark conductivity by incident radiation via inelastic scattering that imparts energy to electrons in trapped states and excites them into the conduction band, without depositing charge. Such radiation-induced conductivity (RIC), caused by ionizing radiation present in harsh space plasma environments, can play a critical role in space charge dissipation within highly insulating materials used in spacecraft. An equilibrium value for RIC, 𝜎_RIC, is attained after prolonged exposure to an incident dose rate; this follows a standard theoretical power law model proposed by Rose/Fowler/Vissenberg, 𝜎_RIC(T …

Analysis Of The Effects Of Surface Modifications And Other Extrinsic Factors On Electron Yield With A “Patch” Model, Matthew Robertson, Christopher Vega, Trace Taylor, Jr Dennison

Conference Proceedings

Electron yield (EY) is a material property of central importance to understanding and modeling spacecraft charging. It depends on incident energy and is unique for each material. Dynamic surface modifications and other extrinsic factors—including composition, surface morphology, contamination, oxidation, and charging— can significantly affect EY and consequently spacecraft charging. This research proposes a “patch” model to provide a simple theoretical framework to model more complex materials comprised of any number of different types of constituent materials in terms of the EY contribution of each constituent material or extrinsic factor. The “patch” model merges the unique EY curve contribution of each …

Effects Of Differing Radiation Methods On Charge Transport In Polymers, Zachary J. Gibson, Jr Dennison, Virginie Griseri

Conference Proceedings

Spacecraft charging issues are understood and mitigated through an understanding of material properties. Material properties are dynamic in the harsh environment of space. Approximations must be made to simulate the space environment in the laboratory. This paper reports on the investigation of the approximation that energy deposition causes the same aging effects in the materials regardless of the radiation source. Samples of polytetrafluoroethylene (PTFE) and polyether-etherketone (PEEK) were irradiated with x-rays, γ-rays, or electrons at total ionizing dose (TID) of either 2 x 10⁴, 2 x 10⁵, or 2 x 10⁶ rad. Charge was then …

Analyzing Atmospheric Gravity Waves Over Antarctica And Visualizing Machine Learning Data, Anastasia N. Brown

Physics Capstone Projects

In an effort to streamline the identification of "clean" windows of airglow images in all sky imager data for the ANGWIN experiment, we have developed a Light Gradient Boosted Machine (LightGBM) learning algorithm that sorts "clean" (marked as 0) wave images from "obscured" (marked as 1) images. These "clean" windows are then processed and undergo FFT-spectrum analysis. We have already successfully created LightGBM models that accurately sort through images taken at the Davis, McMurdo, and Halley research stations in Antarctica. Imager data from the Davis and McMurdo station has been fully processed from the years 2012 to 2022 with clean …

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 …