Physical Sciences and Mathematics Commons^™

Equatorial Disturbance Dynamo Vertical Plasma Drifts Over Jicamarca: Bi‐Monthly And Solar Cycle Dependence, Luis A. Navarro Dominguez, B. G. Fejer, Ludger Scherliess

All Physics Faculty Publications

We use extensive incoherent scatter radar observations from the Jicamarca Radio Observatory to study the local time and bi‐monthly dependence of the equatorial disturbance dynamo vertical plasma drifts on solar flux and geomagnetic activity. We show that the daytime disturbance drifts have generally small magnitudes with largest values before noon and an apparent annual variation. Near dusk, they are downward throughout the year with largest values during the equinoxes and smallest during June solstice. These downward drifts increase strongly with solar flux, and shift to later local times. They also increase with increasing geomagnetically active conditions with no apparent local …

Blandford-Znajek Process In Vacuo And Its Holographic Dual, Ted Jacobson, Maria J. Rodriguez

All Physics Faculty Presentations

Blandford and Znajek discovered a process by which a spinning black hole can transfer rotational energy to a plasma, offering a mechanism for energy and jet emissions from quasars. Here we describe a version of this mechanism that operates with only vacuum electromagnetic fields outside the black hole. The setting, which is not astrophysically realistic, involves either a cylindrical black hole or one that lives in 2+1 spacetime dimensions, and the field is given in simple, closed form for a wide class of metrics. For asymptotically anti–de Sitter black holes in 2+1 dimensions, the holographic dual of this mechanism is …

Usu Materials Physics Group Nasa Missions, Jr Dennison

Posters

No abstract provided.

The Long‐Term Trends Of Nocturnal Mesopause Temperature And Altitude Revealed By Na Lidar Observations Between 1990 And 2018 At Midlatitude, Tao Yuan, Stanley C. Solomon, Chiao -Y. She, D. A. Krueger, Han-Li Liu

All Physics Faculty Publications

The mesopause, a boundary between mesosphere and thermosphere with the coldest atmospheric temperature, is formed mainly by the combining effects of radiative cooling of CO2, and the vertical adiabatic flow in the upper atmosphere. A continuous multidecade (1990‐2018) nocturnal temperature data base of an advanced Na lidar, obtained at Fort Collins, CO (41°N, 105°W), and at Logan, UT (42°N, 112°W), provides an unprecedented opportunity to study the long‐term variations of this important atmospheric boundary. In this study, we categorize the lidar‐observed mesopause into two categories: the “high mesopause” (HM) above 97 km during nonsummer months, mainly formed through the radiative …

Pmc Turbo: Studying Gravity Wave And Instability Dynamics In The Summer Mesosphere Using Polar Mesospheric Cloud Imaging And Profiling From A Stratospheric Balloon, David C. Fritts, Amber D. Miller, C. Bjorn Kjellstrand, Christopher Geach, Bifford P. Williams, Bernd Kaifler, Natalie Kaifler, Glenn Jones, Markus Rapp, Michele Limon, Jason Reimuller, Ling Wang, Shaul Hanany, Sonja Gisinger, Yucheng Zhao, Gunter Stober, Cora E. Randall

All Physics Faculty Publications

The Polar Mesospheric Cloud Turbulence (PMC Turbo) experiment was designed to observe and quantify the dynamics of small‐scale gravity waves (GWs) and instabilities leading to turbulence in the upper mesosphere during polar summer using instruments aboard a stratospheric balloon. The PMC Turbo scientific payload comprised seven high‐resolution cameras and a Rayleigh lidar. Overlapping wide and narrow camera field of views from the balloon altitude of ~38 km enabled resolution of features extending from ~20 m to ~100 km at the PMC layer altitude of ~82 km. The Rayleigh lidar provided profiles of temperature below the PMC altitudes and of the …

Strategies For Determining Electron Yield Material Parameters For Spacecraft Charge Modeling, Phil Lundgreen, Jr Dennison

Conference Proceedings

Modeling of space plasma environment-induced anomalies requires knowledge of:

• Environment and impinging fluxes during spacecraft orbits, which are mission specific and can be incorporated through environmental models and databases.
• Satellite geometry and orientation in the space environment, accomplished through such charging codes as NASCAP-2K, SPENVIS, or MUSCAT.
• Materials used in spacecraft construction, from the specific spacecraft design.
• Relevant materials properties characterizing the interaction of the materials with the environment and how these properties may change with exposure to the space environment.

A reliable, comprehensive database of spacecraft materials and the characterization of those materials is being created in the form …

Electron Yield Measurements Of Multilayer Conductive Materials, Gregory Wilson, Matthew Robertson, Jordan Lee, Jr Dennison

Conference Proceedings

As energetic electrons interact with the surface of materials, they impart energy throughout the material. If the energy exchange is near the surface, secondary electrons within the material can be excited and emitted. It is also possible for the incident primary electron to undergo a quasi-elastic collision within the material, wherein the electron is backscattered and emitted from the surface. As the backscattered electron is leaving the material, it can continue to impart energy to the material, potentially exciting more secondary electrons as it approaches the surface on the way back out.

This process of imparting energy and charge to …

Suppresion Of Electron Yield With Carbon Nanotube Forests: A Case Study, Brian Wood, Jordan Lee, Gregory Wilson, T.-C. Shen, Jr Dennison

Conference Proceedings

Electron emission of carbon nanotube (CNT) forests grown on silicon substrates was measured to investigate possible electron yield suppression due to the composition and morphology of CNT forests. CNT forests are vertically-oriented tubular formations of graphitic carbon grown on a substrate; these have been widely investigated for their extreme properties in optical, electrical, and mechanical aspects of physics and material sciences. CNT coatings are good candidates for yield reduction, in analogy with the near-ideal blackbody optical properties of CNT forests. Carbon with its low atomic number has an inherent low yield due to its low density of bulk electrons. Furthermore, …

Influence Of Vibrationally-Induced Structural Changes On Carbon Nanotube Forests Suppression Of Electron Yield, Jordan Lee, Brian Wood, Gregory Wilson, T.-C. Shen, Jr Dennison

Conference Proceedings

Carbon nanotube (CNT) forest coatings have been found to lower electron yield from material surfaces. The suppressed yields have been attributed to both the lower inherent yields of low-atomic number carbon and the enhanced electron recapture resulting from the morphology of the carbon layer. To explore the relative contributions of these two causes of yield suppression, tests have been made on CNT forest-coated conducting substrate samples subjected to vibrationally-induced changes of the coating structure. The extent of vibrationally-induced structural changes—due, for example, to shear-force conditions during space-vehicle transit—are of interest, as CNT have been a frequent topic of scientific curiosity …

First Ground‐Based Conjugate Observations Of Stable Auroral Red (Sar) Arcs, C. Martinis, J. Baumgardner, M. Mendillo, Michael J. Taylor, T. Moffat-Griffin, J. Wroten, C. Sullivan, R. Macinnis, B. Alford, Y. Nishimura

All Physics Faculty Publications

During the geomagnetic storm of 1 June 2013, all‐sky imagers located at geomagnetically conjugate locations at Millstone Hill, USA (42.6°N, 71.4°W, 50.9° mag lat) and at Rothera, Antarctica (67.5°S, 68.1°W, ‐53.2° mag lat), allowed us to measure a stable auroral red (SAR) arc simultaneously in both hemispheres for the first time. The arc measured in one hemisphere was observed very close to its conjugate location in the opposite hemisphere. While spatial characteristics, such as equatorward motion and latitudinal extent, were similar at both sites, morphological properties, for example, arc brightness and shape of the poleward edges, differed. The overall brightness …

Octonionic Maxwell Equations, Ben Shaw

Physics Capstone Projects

An introduction to Quaternions and Octonions is given, and the Maxwell Equations are formulated in terms of each. The conventional, source-free relativistic theory of eight dimensional electromagnetism is introduced and examined. Similarly, the source-free Octonionic Maxwell Equations are developed, and it is shown that the seven dimensional electric and magnetic fields–pure Octonions–each admit plane wave solutions. An Octonionic Faraday tensor is constructed and compared with the conventional Faraday tensor, and it is shown that, in the source-free case, the conventional and Octonionic theories are equivalent.

The Effects Of Beta Radiation On The Electrostatic Discharge Of Ldpe, Kip Quilter

Physics Capstone Projects

Spacecraft charging is one of the leading causes of space environment induced anomalies [1]. Spacecraft charging occurs when an electric charge builds up on a spacecraft; one way for the charge to accumulate is from natural space plasma [1]. The charge can lead to many different problems, including electrostatic discharge (ESD). Insulating materials such as highly disordered polymers do not allow charge to move freely; this can result in areas of localized charge to build up creating differing electric potentials [2]. Once the difference in potentials is great enough, electrostatic discharge occurs causing irreversible damages to the insulating polymers.

ESD …

Juxtaposition At 45 Km Of Temperatures From Rayleigh-Scatter Lidar And Reanalysis Models, David K. Moser

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Weather and climate forecasts are almost exclusively produced by computer models, which use atmospheric measurements as starting points. It is a well-known and joked-about fact that model predictions can be incorrect at times. One of the reasons this happens is due to gaps in our knowledge of atmospheric conditions in areas where measurements don’t often taken place, such as the mesosphere, which stretches from roughly 45-90 km altitude.

A lidar is a device that can shoot out short bursts of laser light to measure things such as atmospheric thickness at a distance. From this information one can then derive the …

The International Community Coordinated Modeling Center Space Weather Modeling Capabilities Assessment: Overview Of Ionosphere/Thermosphere Activities, Ludger Scherliess, I. Tsagouri, E. Yizengaw, S. Bruinsma, J. S. Shim, A. Coster, J. M. Retterer

All Physics Faculty Publications

The Earth's ionosphere/thermosphere (I/T) system exhibits complicated weather variability that can have adverse effects on human operations and systems, and consequently, there is a need for both accurate and reliable specifications and forecasts for this region. As part of the international effort to evaluate and assess the predictive capabilities of space weather models, four working groups for the I/T system have been created with the goal to devise a concerted model validation effort for the I/T environment. This paper presents an overview of the team efforts and reports on the progress made. As a first step, the working teams have …

General Relativity As A Biconformal Gauge Theory, James Thomas Wheeler

All Physics Faculty Publications

We consider the conformal group of a space of dim n=p+q, with SO(p,q) metric. The quotient of this group by its homogeneous Weyl subgroup gives a principal fiber bundle with 2n-dim base manifold and Weyl fibers. The Cartan generalization to a curved 2n-dim geometry admits an action functional linear in the curvatures. Because symmetry is maintained between the translations and the special conformal transformations in the construction, these spaces are called biconformal; this same symmetry gives biconformal spaces overlapping structures with double field theories, including manifest T-duality. We establish that biconformal geometry is …

A Modeling Study Of The Responses Of Mesosphere And Lower Thermosphere Winds To Geomagnetic Storms At Middle Latitudes, Jingyuan Li, Wenbin Wang, Jianyong Lu, Jia Yue, Alan G. Burns, Tao Yuan, Xuetao Chen, Wenjun Dong

All Physics Faculty Publications

Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIMEGCM) simulations are diagnostically analyzed to investigate the causes of mesosphere and lower thermosphere (MLT) wind changes at middle latitudes during the 17 April 2002 storm. In the early phase of the storm, middle‐latitude upper thermospheric wind changes are greater and occur earlier than MLT wind changes. The horizontal wind changes cause downward vertical wind changes, which are transmitted to the MLT region. Adiabatic heating and heat advection associated with downward vertical winds cause MLT temperature increases. The pressure gradient produced by these temperature changes and the Coriolis force then drive strong equatorward …

Porting Symbolic Libraries From Maple To Python, James Lewis

Physics Capstone Projects

Utah State University has a database of tables of the known solutions of the Einstein Field Equation. This database is primarily recorded in the symbolic computing program Maple. This database needs to be translated into Python code so the information can be more accessible to the general public. This translation was successful for one table, which means that it is possible to translate the entire database.

On The Long Lasting “C‐Type” Structures In The Sodium Lidargram: The Lifetime Of Kelvin‐Helmholtz Billows In The Mesosphere And Lower Thermosphere Region, S. Mondal, S. Sarkhel, Jay Agarwal, D. Chakrabarty, R. Sekar, Tao Yuan, Xuguang Cai, Alan Z. Liu, Satonori Nozawa, Norihito Saito, Takuya D. Kawahara, Martin G. Mlynczak, James M. Russell Iii

All Physics Faculty Publications

In order to understand the characteristics of long‐lasting “C‐type” structure in the Sodium (Na) lidargram, six cases from different observational locations have been analyzed. The Na lidargram, collected from low‐, middle‐, and high‐latitude sites, show long lifetime of the C‐type structures which is believed to be the manifestation of Kelvin‐Helmholtz (KH) billows in the Mesosphere and Lower Thermosphere (MLT) region. In order to explore the characteristics of the long‐lasting C‐type structures, the altitude profile of square of Brunt‐Väisälä frequency in the MLT region has been derived using the temperature profile collected from the Na lidar instruments and the SABER instrument …

Mathematica Program To Compute Klein Gordon Equation For Generic Black Holes, Brant Smith

Physics Capstone Projects

The goal of this project is to develop a program that will compute the Klein Gordon equation for generic Black Holes through the program Mathematica. This program will be available on Utah State websites for public usage. This project focuses on an understanding of General Relativity and more concretely on theoretical aspects of Black Holes. Developing the program begins with computing the Laplace equation in flat space to understand what it means to have empty space without a Black Hole. The Klein Gordon equation for a Schwarzschild Black Hole is then solved to show what happens once a static, non-rotating …

Physics 4900, David Maughan

Physics Capstone Projects

More than a century has passed since Albert Einstein published his general theory of relativity. The theory has been tested many times experimentally, primarily in the relatively weak gravitational fields of the solar system [1,2]. More recently the first experimental results from the strong gravitational fields of two black holes have been measured in the form of gravitational waves, which are another prediction of general relativity. The 2017 Nobel prize in physics was awarded to Kip Thorne, Rainer Weiss, and Barry Barish for their role in the detection of gravitational waves. This year we have seen the first image of …

Thermodynamic Properties Of Black Holes, Geoffrey Schulthess

Physics Capstone Projects

Black Holes are some of the most mysterious objects in the known universe. In 1975, Stephen Hawking stated that Black Holes can behave as thermodynamical objects with a finite mass, spin, angular velocity, temperature, and entropy. This has been one of the most fascinating yet perplexing breakthroughs in our understanding of these strongly gravitating objects. In this context, the purpose of this research was to use Wolfram Mathematica to create a program that would calculate the thermodynamic properties of a black hole, given a certain metric.

Thermal Oxidation Of Silicon In A Home-Made Furnace System, Joshua Koskan

Physics Capstone Projects

I approached Dr. Shen with a desire for a project in understanding how to manage and expand the capabilities of a laboratory. After some discussion, my senior project was to complete a gas and water chiller system to an existing furnace for chemical vapor deposition. It should be able to handle temperatures up to 1100 ºC, hold a vacuum to mTorr, be easy to move samples in and out of the furnace, and cost effective.

Photochemistry On The Bottom Side Of The Mesospheric Na Layer, Tao Yuan, Wuhu Feng, John M. C. Plane, Daniel R. Marsh

All Physics Faculty Publications

Lidar observations of the mesospheric Na layer have revealed considerable diurnal variations, particularly on the bottom side of the layer, where more than an order-of-magnitude increase in Na density has been observed below 80 km after sunrise. In this paper, multi-year Na lidar observations are utilized over a full diurnal cycle at Utah State University (USU) (41.8o N, 111.8o W) and a global atmospheric model of Na with 0.5 km vertical resolution in the mesosphere and lower thermosphere (WACCM-Na) to explore the dramatic changes of Na density on the bottom side of the layer. Photolysis of the principal reservoir NaHCO3 …

The Water Entry Of A Sphere In A Jet, Nathan B. Spiers, Jesse Belden, Zhao Pan, Sean Holekamp, George Badlissi, Matthew Jones, Tadd T. Truscott

Mechanical and Aerospace Engineering Faculty Publications

The forces on an object impacting the water are extreme in the early moments of water entry and can cause structural damage to biological and man-made bodies alike. These early-time forces arise primarily from added mass, peaking when the submergence is much less than one body length. We experimentally investigate a means of reducing impact forces on a rigid sphere by placing the sphere inside a jet of water so that the jet strikes the quiescent water surface prior to entry of the sphere into the pool. The water jet accelerates the pool liquid and forms a cavity into which …

Radar Studies Of Height-Dependent Equatorial F Region Vertical And Zonal Plasma Drifts, S. A. Shidler, F. S. Rodrigues, B. G. Fejer, M. A. Milla

All Physics Faculty Publications

We present the results of an analysis of long-term measurements of ionospheric F region E × B plasma drifts in the American/Peruvian sector. The analysis used observations made between 1986 and 2017 by the incoherent scatter radar of the Jicamarca Radio Observatory. Unlike previous studies, we analyzed both vertical and zonal components of the plasma drifts to derive the geomagnetically quiet time climatological variation of the drifts as a function of height and local time. We determine the average behavior of the height profiles of the drifts for different seasons and distinct solar flux conditions. Our results show good agreement …

Water Entry Of Spheres At Various Contact Angles, Nathan B. Spiers, Mohammad M. Mansoor, Jesse Belden, Tadd T. Truscott

Mechanical and Aerospace Engineering Faculty Publications

It is well known that the water entry of a sphere causes cavity formation above a critical impact velocity as a function of the solid-liquid contact angle (Duez et al. 2007). Using a rough sphere with a contact angle of 120^◦, Aristoff & Bush (2009) showed that there are four different cavity shapes dependent on the Bond and Weber numbers (i.e., quasi-static, shallow, deep and surface). We experimentally alter the Bond number, Weber number and contact angle of smooth spheres and find two key additions to the literature: 1) Cavity shape also depends on the contact angle; 2) …

Thermal Structure Of The Mesopause Region During The Wadis-2 Rocket Campaign, Raimund Wörl, Boris Strelnikov, Timo P. Viehl, Josef Höffner, Pierre-Dominique Pautet, Michael J. Taylor, Yucheng Zhao, Franz-Josef Lübken

Publications

This paper presents simultaneous temperature measurements by three independent instruments during the WADIS-2 rocket campaign in northern Norway (69^◦ N, 14^◦ E) on 5 March 2015. Vertical profiles were measured in situ with the CONE instrument. Continuous mobile IAP Fe lidar (Fe lidar) measurements during a period of 24 h, as well as horizontally resolved temperature maps by the Utah State University (USU) Advanced Mesospheric Temperature Mapper (AMTM) in the mesopause region, are analysed. Vertical and horizontal temperature profiles by all three instruments are in good agreement. A harmonic analysis of the Fe lidar measurements shows the presence …

Spacetime Groups, Ian M. Anderson, Charles G. Torre

Publications

A spacetime group is a connected 4-dimensional Lie group G endowed with a left invariant Lorentz metric h and such that the connected component of the isometry group of h is G itself. The Newman-Penrose formalism is used to give an algebraic classification of spacetime groups, that is, we determine a complete list of inequivalent spacetime Lie algebras, which are pairs (g,η), with g being a 4-dimensional Lie algebra and η being a Lorentzian inner product on g. A full analysis of the equivalence problem for spacetime Lie algebras is given which leads to a completely algorithmic solution to the …

Storm-Time Thermospheric Winds Over Peru, Luis A. Navarro Dominguez, B. G. Fejer

All Physics Faculty Publications

We used Fabry-Perot Interferometer (FPI) observations at Jicamarca, Nasca and Arequipa, Peru from 2011 to 2017 to study the nighttime zonal and meridional disturbance winds over the Peruvian equatorial region. We derived initially the seasonal-dependent average thermospheric winds corresponding to 12 hours of continuous geomagnetically quiet conditions. These quiet-time climatological winds, which are in general agreement with results from the Horizontal Wind Model (HWM14), were then used as baselines for the calculation of the disturbance winds. Our results indicate that the nighttime zonal disturbance winds are westward with peak values near midnight and with magnitudes much larger than predicted by …

A Multi-Ion, Flux-Corrected Transport Based Hydrodynamic Model For The Plasmasphere Refilling Problem, Kausik Chatterjee, Robert W. Schunk

All Physics Faculty Publications

The objective of this paper is the application of a newly-developed Flux-Corrected Transport (FCT) based hydrodynamic solution methodology to the plasmasphere refilling problem following a geomagnetic storm. The FCT method is extremely well-suited to the solution of nonlinear partial differential equations with shocks and discontinuities. In this solution methodology, every ion species is modeled as two separate fluids originating from the northern and southern hemispheres. We present refilling results that includes three ion (H⁺, He⁺ and O⁺) species and two neutrals (H and O). We believe that with additional modifications, the model …