Physics Commons^™

Modeling The Electrodynamics Of The Low-Latitude Ionosphere, Christian Stephen Wohlwend

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The electrodynamics of the Earth's low-latitude ionosphere is dependent on the ionospheric conductivity and the thermospheric neutral density, temperature, and winds present. This two-part study focused on the gravity wave seeding mechanism of equatorial plasma depletions in the ionosphere and the associated equatorial spread F, as well as the differences between a two-dimensional flux tube integrated electrodynamics model and a three-dimensional model for the same time period. The gravity wave seeding study was based on a parameterization of a gravity wave perturbation using a background empirical thermosphere and a physics-based ionosphere for the case of 12 UT on 26 September …

Intergranular Phases In Cyclically Annealed Yba2cu3o7-X And Their Implications For Critical Current Densities, Andrew Peter Clarke

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

We report changes in the intergranular material and grain morphology of YBa₂Cu₃O_7-x during cyclic anneals between 780 and 980 ºC in oxygen at atmospheric pressure. Two endothermic reactions were detected: (a) the eutectic reaction of YBa₂Cu₃O_7-x with CuO and BaCuO₂ at 900 ºC (enthalpy ∆H_a) and (b) the peritectic reaction of YBa₂Cu₃O_7-x with CuO at 950 ºC (∆H_b). During the first anneal, only reaction (b) is detected, and although it should only occur if there is an excess of CuO, …

The Adaptability Of Langmuir Probes To The Pico-Satellite Regime, Andrew Jay Auman

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The purpose of this thesis is to investigate whether it is feasible to use Langmuir probes on pico-satellites flying in low Earth orbit over mid- to low-latitude geographic regions. Following chapters on the expected ionospheric conditions and an overview of Langmuir probe theory, a chapter addressing the difficulties involved with pico-satellite Langmuir probes is presented. Also, the necessary satellite-to-probe surface area requirements in order to achieve confidence in pico-satellite Langmuir probe data, for the orbital regions of interest to this thesis, are stated.

Extending F10.7'S Time Resolution To Capture Solar Flare Phenomena, Ariel O. Acebal

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Solar ultraviolet (UV) radiation ionizes the neutral components in the atmosphere, which is partly responsible for the formation of the ionosphere, and contributes to heating of the atmosphere. Solar flares change the solar spectrum at times by several orders of magnitude. These changes modify the Earth's upper atmosphere, causing problems to communication systems and space operations, such as increased satellite drag. Unfortunately, solar UV measurements are limited since they can only be observed with space-based sensors. In order to work around this limitation, the solar radio emissions at a wavelength of 10.7 cm have been used as a proxy for …

Usu’S Rayleigh-Scatter Lidar, Vincent B. Wickwar

Presentations

No abstract provided.

Seasonal Variations Of Semidiurnal Tidalperturbations In Mesopause Region Temperature And Zonal And Meridional Winds Above Fort Collins, Colorado(40.6°N, 105.1°W), Tao Yuan, H. Schmidt, C. Y. She, D. A. Krueger, S. Reising

All Physics Faculty Publications

On the basis of Colorado State University (CSU) Na lidar observations over full diurnal cycles from May 2002 to April 2006, a harmonic analysis was performed to extract semidiurnal perturbations in mesopause region temperature and zonal and meridional winds over Fort Collins, Colorado (40.6°N, 105.1°W). The observed monthly results are in good agreement with MF radar tidal climatology for Urbana, Illinois, and with predictions of the Hamburg Model of the Neutral and Ionized Atmosphere (HAMMONIA), sampled at the CSU Na lidar coordinates. The observed semidiurnal tidal period perturbation within the mesopause region is found to be dominated by propagating modes …

Seasonal And Longitudinal Dependence Of Equatorialdisturbance Vertical Plasma Drifts, Bela G. Fejer, J. W. Jensen, S. Y. Su

Bela G. Fejer

[1] We used equatorial measurements from the ROCSAT-1 satellite to determine the seasonal and longitudinal dependent equatorial F region disturbance vertical plasma drifts. Following sudden increases in geomagnetic activity, the prompt penetration vertical drifts are upward during the day and downward at night, and have strong local time dependence at all seasons. The largest prompt penetration drifts near dusk and dawn occur during June solstice. The daytime disturbance dynamo drifts are small at all seasons. They are downward near dusk with largest (smallest) values during equinox (June solstice); the nighttime drifts are upward with the largest magnitudes in the postmidnight …

Deep Dielectric Charging Of Spacecraft Polymers By Energetic Protons, Nelson W. Green, Jr Dennison

Journal Articles

The majority of research in the field of spacecraft charging concentrates on electron charging effects with little discussion of charging by protons. For spacecraft orbiting in the traditional LEO and GEO environments, this emphasis on electrons is appropriate since energetic electrons are the dominant species. However, for spacecraft in orbits within the inner radiation belts, or for interplanetary and lunar space probes, proton charging effects may also be of concern. To examine bulk spacecraft charging effects in these environments, several typical highly insulating spacecraft polymers were exposed to energetic protons with energies from 1 to 10 MeV to simulate protons …

Temperature And Electric Field Dependence Of Conduction In Low-Density Polyethylene, John R. Dennison, Jerilyn Brunson

All Physics Faculty Publications

A traditional constant voltage conductivity test method was used to measure how the conductivity of highly insulating low-density polyethylene (LDPE) polymer films depends on applied electric field, repeated and prolonged electric field exposure, and sample temperature. The strength of the applied voltage was varied to determine the electric field dependence. At low electric field, the resistivity was measured from cryogenic temperatures to well above the glass transition temperature. Comparisons were made with a variety of models of the conduction mechanisms common in insulators, including transient polarization and diffusion and steady-state thermally activated hopping conductivity and variable range hopping conductivity, to …

Low-Fluence Electron Yields Of Highly Insulating Materials, Ryan Hoffmann, Jr Dennison, Clint D. Thomson, Jennifer Albretson

Journal Articles

Electron-induced electron yields of high-resistivity, high-yield materials - ceramic polycrystalline aluminum oxide and the polymer polyimide (Kapton HN), - were made by using a low-fluence, pulsed incident electron beam and charge neutralization electron source to minimize charge accumulation. Large changes in energy-dependent total yield curves and yield decay curves were observed, even for incident electron fluences of <3 fC/mm². The evolution of the electron yield as charge accumulates in the material is modeled in terms of electron re-capture based on an extended Chung-Everhart model of the electron emission spectrum. This model is used to explain anomalies measured in highly insulating, …

Gravity Wave And Tidal Influences On Equatorial Spread F Based On Observations During The Spread F Experiment (Spreadfex), D. C. Fritts, S. L. Vadas, D. M. Riggin, M. A. Abdu, I. S. Batista, H. Takahashi, A. Medeiros, F. Kamalabadi, H. L. Liu, B. G. Fejer, Michael J. Taylor

All Physics Faculty Publications

The Spread F Experiment, or SpreadFEx, was performed from September to November 2005 to define the potential role of neutral atmosphere dynamics, primarily gravity waves propagating upward from the lower atmosphere, in seeding equatorial spread F (ESF) and plasma bubbles extending to higher altitudes. A description of the SpreadFEx campaign motivations, goals, instrumentation, and structure, and an overview of the results presented in this special issue, are provided by Fritts et al. (2008a). The various analyses of neutral atmosphere and ionosphere dynamics and structure described in this special issue provide enticing evidence of gravity waves arising from deep convection in …

Low-Fluence Electron Yields Of Highly Insulating Materials, Ryan Hoffman, John R. Dennison, Clint D. Thomson, Jennifer Albresten

All Physics Faculty Publications

Electron-induced electron yields of high-resistivity high-yield materials - ceramic polycrystalline aluminum oxide and polymer polyimide (Kapton HN) - were made by using a low-fluence pulsed incident electron beam and charge neutralization electron source to minimize charge accumulation. Large changes in the energy-dependent total yield curves and yield decay curves were observed, even for incident electron fluences of < 3 fC/mm². The evolution of the electron yield as charge accumulates in the material is modeled in terms of electron recapture based on an extended Chung-Everhart model of the electron emission spectrum. This model is used to explain the anomalies measured in highly …

Low-Fluence Electron Yields Of Highly Insulating Materials, Ryan Hoffmann, John R. Dennison

All Physics Faculty Publications

Electron-induced electron yields of high-resistivity, high-yield materials - ceramic polycrystalline aluminum oxide and the polymer polyimide (Kapton HN), - were made by using a low-fluence, pulsed incident electron beam and charge neutralization electron source to minimize charge accumulation. Large changes in energy-dependent total yield curves and yield decay curves were observed, even for incident electron fluences of

Rare Measurements Of A Sprite With Halo Event Driven By A Negative Lightning Discharge Over Argentina, Michael J. Taylor, T. Berkey, Pierre-Dominique Pautet, S. A. Cummer, N. Jaugey, J. N. Thomas, N. N. Solorzano, F. Sao Sabbas, R. H. Holzworth, O. Pinto, N. J. Schuch

All Physics Faculty Publications

As part of a collaborative campaign to investigate Transient Luminous Events (TLEs) over South America, coordinated optical, ELF/VLF, and lightning measurements were made of a mesoscale thunderstorm observed on February 22–23, 2006 over northern Argentina that produced 445 TLEs within a 6 hour period. Here, we report comprehensive measurements of one of these events, a sprite with halo that was unambiguously associated with a large negative cloud-to-ground (CG) lightning discharge with an impulsive vertical charge moment change (DMQv) of 03 C.km. This event was similar in its location, morphology and duration to other positive TLEs observed from this storm. However, …

Core-Level Spectroscopy Of The Ni/W(110) Interface: Correlation Of W Interfacial Core Levelshifts With First-Layer Ni Phases, D. Mark Riffe, R. T. Franckowiak, N. D. Shinn, B. Kim, K. J. Kim, T. H. Kang

All Physics Faculty Publications

We have measured W 4f_7/2 core-level photoemission spectra from W(1 1 0) in the presence of Ni overlayers, from ∼0.2 to ∼3 monolayers. Interfacial core-level shifts associated with first-layer Ni phases have been identified: −230 ± 15 meV for the 1 × 1 pseudomorphic phase and −70 ± 7 meV for the 7 × 1 close-packed commensurate phase. At higher Ni coverages the interfacial core-level shift is −100 ± 10 meV. These shifts are analyzed using the partial-shift model of Nilsson et al. [Phys. Rev. B 38 (1988) 10357]; the analysis indicates that the difference in binding energies between …

Resistivity As Dynamic Behavior In Low Density Polyethylene, J. Brunson, John R. Dennison

All Physics Faculty Publications

Bridging the gap between theoretical calculations and experimental data has been the focus of much of the research into the electrical behavior of insulating polymers. Low density polyethylene is the standard test material used in both experimental work and numerical calculations. Resistivity measurements provide more than an absolute value for technical use; they also provide insight into the nature of active charge carriers and trapping behavior within LDPE.

Quiet Time Equatorial F Region Vertical Plasma Drift Model Derived From Rocsat-1 Observations, Bela G. Fejer, J. W. Jensen, S. Y. Su

Bela G. Fejer

[1] We have used five years of measurements on board the ROCSAT-1 satellite to develop a detailed quiet time global empirical model for equatorial F region vertical plasma drifts. This model describes the local time, seasonal and longitudinal dependence of the vertical drifts for an altitude of 600 km under moderate and high solar flux conditions. The model results are in excellent agreement with measurements from the Jicamarca radar and also from other ground-based and in situ probes. We show that the longitudinal dependence of the daytime and nighttime vertical drifts is much stronger than reported earlier, especially during December …

Launch And Deployment Of The Misse-6 Payload: State Of Utah Space Environment & Contamination Study, Joshua Hodges, Jeff Duce, Jr Dennison

Presentations

No abstract provided.

Algorithm Development Of The Aglite-Lidar Instrument, Christian Marchant

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Particulate emissions from agricultural operations are increasingly receiving attention from regulatory bodies as a potential source of air pollution. The Space Dynamics Laboratory (SDL) has developed the Aglite system, a suite of instruments including a lidar that is capable of measuring particulate emission levels from agricultural facilities. This system provides a novel method of measuring particulate mass (PM) pollution, allowing measurements to be taken of diverse types of facilities with high temporal and spatial resolution. This high resolution allows for the measurement of emission levels generated by specific activities, fostering the development and determination of best management practices.

The Aglite …

Large-Amplitude Temperature Waves In The Upper Atmosphere, Jarron Lembke, Vincent B. Wickwar

Posters

Recent LIDAR research at USU found a noctilucent cloud (NLC) near the minimum of a large-amplitude temperature wave in the upper mesosphere. Such a large-amplitude wave had not been seen previously. Initial analysis suggested that this wave might be related to the diurnal tide, but greatly amplified. This research set out to learn whether these waves are a common feature. Large waves or temperature “bumps” exceeding 10 K were found in more than half the observations. A later stage will be to see if they are linked to the tides.

F3 Layerduring Penetration Electric Field, N. Balan, H. Alleyne, S. V. Thampi, K. Lynn, Y. Otsuka, Bela G. Fejer, M. A. Abdu

Bela G. Fejer

[1] The occurrence of an additional layer, called F3 layer, in the equatorial ionosphere at American, Indian, and Australian longitudes during the super double geomagnetic storm of 7–11 November 2004 is presented using observations and modeling. The observations show the occurrence, reoccurrence, and quick ascent to the topside ionosphere of unusually strong F3 layer in Australian longitude during the first super storm (8 November) and in Indian longitude during the second super storm (10 November), all with large reductions in peak electron density (Nmax) and total electron content (GPS-TEC). The unusual F3 layers can arise mainly from unusually strong fluctuations …

Climatology Of Mesopause Region Temperature, Zonal Wind, And Meridional Wind Over Fort Collins,Colorado (41°N, 105°W), And Comparison With Model Simulations, Tao Yuan, C. Y. She, D. A. Krueger, F. Sassi, R. Garcia, R. G. Roble, H. Liu, H. Schmidt, Steven Reising

All Physics Faculty Publications

Between May 2002 and April 2006, many continuous observations of mesopause region temperature and horizontal wind, each lasting longer than 24 h (termed full-diurnal-cycle observations), were completed at the Colorado State University Na Lidar Facility in Fort Collins, Colorado (41°N, 105°W). The combined data set consists of 120 full-diurnal-cycle observations binned on a monthly basis, with a minimum of 7 cycles in April and a maximum of 18 cycles in August. Each monthly data set was analyzed to deduce mean values and tidal period perturbations. After removal of tidal signals, monthly mean values are used for the study of seasonal …

Relation Between The Occurrence Rate Of Esf And The Verticalplasma Drift Velocity At Sunset Derived Form Global Observations, C. Stolle, H. Luhr, Bela G. Fejer

Bela G. Fejer

In this study, we investigate two global climatological data sets; the occurrence rate of Equatorial Spread- F (ESF), associated with equatorial plasma irregularities, at 400 km altitude obtained from CHAMP observations, and the evening equatorial vertical plasma drift, vz, from ROCSAT-1 measurements. First, as retrieved for a solar flux level of F10.7=150, the longitudinal variation of the two independently derived quantities correlates between 84% and 93% in the seasons December solstice, equinox and June solstice. The highest correlation is found for the solstice seasons when vz is integrated over local time around the prereversal enhancement (PRE) and displaced 6 towards …

Gravity Wave And Tidalinfluences On Equatorial Spread F Based On Observations During The Spread F Experiment(Spreadfex), D. C. Fritts, S. L. Vadas, D. M. Riggin, M. A. Abdu, I. S. Batista, H. Takahashi, A. Medeiros, F. Kalamabadi, H. L. Liu, Bela G. Fejer, M. J. Taylor, F. Vargas

Bela G. Fejer

The Spread F Experiment, or SpreadFEx, was performed from September to November 2005 to define the potential role of neutral atmosphere dynamics, primarily gravity waves propagating upward from the lower atmosphere, in seeding equatorial spread F (ESF) and plasma bubbles extending to higher altitudes. A description of the SpreadFEx campaign motivations, goals, instrumentation, and structure, and an overview of the results presented in this special issue, are provided by Fritts et al. (2008a). The various analyses of neutral atmosphere and ionosphere dynamics and structure described in this special issue provide enticing evidence of gravity waves arising from deep convection in …

Photoelectric Charging By Ultraviolet Light Of A Lunar Dust Simulant In A Microgravity Environment, Microgravity Research Team 2008

Reports and Proposals

No abstract provided.

Driving The Ting Model With Gaim Electron Densities: Ionospheric Effects On The Thermosphere, G. Jee, A. G. Burns, W. Wang, S. C. Solomon, Robert W. Schunk, L. Scherliess, D. C. Thompson, Jan Josef Sojka, Lie Zhu

All Physics Faculty Publications

In order to study the effects of ionospheric plasma densities on the thermosphere, the electron and O+ densities in the Thermosphere Ionosphere Nested Grid (TING) model were replaced by electron densities from the Global Assimilation of Ionospheric Measurements (GAIM) model at pressure level z = 0 (about 210 ~ 230 km altitude) and above. This GAIM-derived TING model (G-TING) was then run for the period 1–4 April 2004. The TING model was also run as a stand-alone coupled model (S-TING), without using the GAIM electron densities, for the same period. The resulting thermospheric responses from the two simulations were compared …