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Utah State University

2012

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Articles 1 - 30 of 107

Full-Text Articles in Physics

Changes In Thermospheric Temperature Induced By High-Speed Solar Wind Streams, Larry Gardner, Jan J. Sojka, Robert W. Schunk, Rod Heelis Dec 2012

Changes In Thermospheric Temperature Induced By High-Speed Solar Wind Streams, Larry Gardner, Jan J. Sojka, Robert W. Schunk, Rod Heelis

All Physics Faculty Publications

During high-speed stream (HSS) events the solar wind speed increases, and the cross polar cap potential increases, leading to increased Joule heating at high latitudes. The heat input at high latitudes heats the polar regions, which then conducts to lower latitudes, producing global heating. The heating occurs during the risetime of the cross polar cap potential and throughout the period of high cross polar cap potential as seen in our simulation. These simulations are performed using the Utah State University global thermosphere model driven by Joule heating rates that are consistent with electric fields observed by DMSP-15 observations of HSS ...


First Temperature Observations With The Usu Very Large Rayleigh Lidar: An Examination Of Mesopause Temperatures, Leda Sox, Vincent B. Wickwar, Joshua P. Herron, Marcus J. Bingham, Lance W. Petersen, Matthew T. Emerick Dec 2012

First Temperature Observations With The Usu Very Large Rayleigh Lidar: An Examination Of Mesopause Temperatures, Leda Sox, Vincent B. Wickwar, Joshua P. Herron, Marcus J. Bingham, Lance W. Petersen, Matthew T. Emerick

Posters

As the impetus for extended observational measurements throughout the middle atmosphere has increased1 , the limits of previous instrumentation need to be pushed. The Rayleigh lidar group at the Atmospheric Lidar Observatory (ALO) at Utah State University has pushed such limits on existing Rayleigh scatter lidar technology and, through major upgrades to the previous lidar system, has been able to gather temperature measurements in the upper mesosphere and lower thermosphere from approximately 70P109 km. A data campaign with the new system was conducted around the annual temperature minimum, centered on late June 2012, in this region. The temperatures from this campaign ...


Multiple Peaks In Saber Mesospheric Oh Emission Altitude Profiles, Jordan Rozum, Gene A. Ware, Doran J. Baker, Martin G. Wlynczak, James M. Russell Dec 2012

Multiple Peaks In Saber Mesospheric Oh Emission Altitude Profiles, Jordan Rozum, Gene A. Ware, Doran J. Baker, Martin G. Wlynczak, James M. Russell

Browse All Undergraduate research

No abstract provided.


The Application Of Tomographic Reconstruction Techniques To Ill-Conditioned Inverse Problems In Atmospheric Science And Biomedical Imaging, Vern Philip Hart Ii Dec 2012

The Application Of Tomographic Reconstruction Techniques To Ill-Conditioned Inverse Problems In Atmospheric Science And Biomedical Imaging, Vern Philip Hart Ii

All Graduate Theses and Dissertations

A methodology is presented for creating tomographic reconstructions from various projection data, and the relevance of the results to applications in atmospheric science and biomedical imaging is analyzed. The fundamental differences between transform and iterative methods are described and the properties of the imaging configurations are addressed. The presented results are particularly suited for highly ill-conditioned inverse problems in which the imaging data are restricted as a result of poor angular coverage, limited detector arrays, or insufficient access to an imaging region. The class of reconstruction algorithms commonly used in sparse tomography, the algebraic reconstruction techniques, is presented, analyzed, and ...


In Situ Measurements Of Electron-Beam-Induced Surface Voltage Of Highly Resistive Materials, Joshua Hodges Dec 2012

In Situ Measurements Of Electron-Beam-Induced Surface Voltage Of Highly Resistive Materials, Joshua Hodges

All Graduate Theses and Dissertations

This study presents the development, calibration, characterization, and use of new instrumentation for in situ measurements of electron-beam-induced surface voltage. The instrument capabilities allow for measurements of a full range of insulating materials that are of concern to NASA spacecraft charging experts. These measurements are made using moveable capacitive sensor electrodes that can be swept across the sample using an in vacu stepper motor. Testing has shown a voltage range of more than ±30 kV with a low-voltage resolution of 0.2 V. The movable sensors allow for a radial measurement of surface voltage with spatial resolution as low as ...


Defect-Driven Dynamic Model Of Electrostatic Discharge And Endurance Time Measurements Of Polymeric Spacecraft Materials, Charles Sim, Alec Sim, Jr Dennison, Matthew Stormo Nov 2012

Defect-Driven Dynamic Model Of Electrostatic Discharge And Endurance Time Measurements Of Polymeric Spacecraft Materials, Charles Sim, Alec Sim, Jr Dennison, Matthew Stormo

All Physics Faculty Presentations

Charge buildup on insulating materials in the space environment can produce long exposure to electric fields, which can lead to Electrostatic Discharge (ESD). Charge buildup is the leading cause of spacecraft failure due to space environment interactions. ESD can be thought of as the point at which the buildup of charge in localized defects, found in polymeric insulating materials, leads to a catastrophic change in electrical conductivity, which can cause the materials to structurally breakdown. Defects produced by radiation, or prolonged exposure to electric fields, significantly alter the endurance time, the time it takes to produce enough defects to generate ...


Defect-Driven Dynamic Model Of Electrostatic Discharge And Endurance Time Measurements Of Polymeric Spacecraft Materials, Charles Sim, Alec Sim, Jr Dennison, Matthew Stormo Nov 2012

Defect-Driven Dynamic Model Of Electrostatic Discharge And Endurance Time Measurements Of Polymeric Spacecraft Materials, Charles Sim, Alec Sim, Jr Dennison, Matthew Stormo

Posters

Charge buildup on insulating materials in the space environment can produce long exposure to electric fields, which can lead to Electrostatic Discharge (ESD). Charge buildup is the leading cause of spacecraft failure due to space environment interactions. ESD can be thought of as the point at which the buildup of charge in localized defects, found in polymeric insulating materials, leads to a catastrophic change in electrical conductivity, which can cause the materials to structurally breakdown. Defects produced by radiation, or prolonged exposure to electric fields, significantly alter the endurance time, the time it takes to produce enough defects to generate ...


Viscous And Induced Current Heating In Plasma Focus Plasmoids, Ahmad Talaei, Eric Lerner Oct 2012

Viscous And Induced Current Heating In Plasma Focus Plasmoids, Ahmad Talaei, Eric Lerner

Graduate Student Presentations

Recently, Abolhasani et al, proposed that the high ion energies observed in plasmoids formed in the plasma focus could be explained by viscous heating. We here elaborate this proposal, demonstrating that during plasmoid formation, ion motion along magnetic field lines can be rapidly converted, at least in part, to thermal energy through viscous diffusion. This effect is strongly enhanced by higher-z ions. We compare the theoretical predictions with the recent observation by Lerner et al, of trapped ion energies of 160 keV. In addition, we propose a second source of heating. The mildly relativistic electron beam emitted by the plasmoid ...


Modeling Spiral Galaxy Luminosity Profiles, Jordan Rozum, Matt Garlock, Shane L. Larson, Bradley W. Carroll Oct 2012

Modeling Spiral Galaxy Luminosity Profiles, Jordan Rozum, Matt Garlock, Shane L. Larson, Bradley W. Carroll

Browse All Undergraduate research

The distribution of spiral and bar galaxy inclination an- gles is expected to be uniform. However, analysis of sev- eral major galaxy catalogs shows this is not the case; galaxies oriented near edge-on are significantly more common in these catalogs. In an attempt to explain this discrepancy, we have developed a galaxy simulation code to compute the appearance of a spiral type galaxy as a function of its morphological parameters. We examine the dependence of observed brightness upon inclination angle by using smooth luminous mass density and in- terstellar medium (ISM) density distributions. The lu- minous mass component is integrated ...


Extending The Band Model Of Disordered Sio2 Through Cathodoluminescence Studies, Amberly Evans, Gregory Wilson, Jr Dennison, Justin Dekany Oct 2012

Extending The Band Model Of Disordered Sio2 Through Cathodoluminescence Studies, Amberly Evans, Gregory Wilson, Jr Dennison, Justin Dekany

Presentations

Optical coatings of disordered thin film SiO2/SiOx dielectric samples on reflective metal substrates exhibited electron-induced luminescence (cathodoluminescence) under electron beam irradiation in an ultrahigh vacuum chamber at the USU facilities,. These experiments provided measurements of the absolute radiance and emission spectra as functions of incident electron energy, flux and power over a range of sample temperatures (300 K to 40 K). Early results from these experiments have led to a preliminary model of the band structure of highly disordered trapped states within the band gap of SiO2. We now extend this model to further describe the ...


Power And Charge Deposition In Multilayer Dielectrics From Monoenergetic Electron Bombardment, Gregory Wilson, Amberly Evans, Justin Dekany, Jr Dennison Oct 2012

Power And Charge Deposition In Multilayer Dielectrics From Monoenergetic Electron Bombardment, Gregory Wilson, Amberly Evans, Justin Dekany, Jr Dennison

Presentations

Power and charge deposition in multilayer dielectrics from electron bombardment is dependent upon the flux and electron range of the electron beam, where the range,--a lso known as the penetration depth—is dependent upon the incident beam energy. Using the Continuous Slow Down Approximation (CSDA), a composite analytical formula has been developed to relate the electron range to the dose rate and subsequently to the deposited power in each subsequent layer. Based on the constituent layer geometry and material , the deposited charge can also be inferred. To validate these models two separate experiments were conducted, one based on the ...


High-Frequency Pulsed-Electro-Acoustic (Pea) Measurements For Mapping Charge Distribution, Kristina Sorensen, Lee H. Pearson, Jr Dennison, Timothy E. Doyle, Kent D. Hartley Oct 2012

High-Frequency Pulsed-Electro-Acoustic (Pea) Measurements For Mapping Charge Distribution, Kristina Sorensen, Lee H. Pearson, Jr Dennison, Timothy E. Doyle, Kent D. Hartley

Presentations

No abstract provided.


Histological Analysis Of Biological Tissues Using High-Frequency Ultrasound, Kristina Sorensen, Tim Doyle, B. D. Borget, M. Cervantes, H, A. Chappell, B. J. Curtis, M. A. Grover, J. E. Roring, J. E. Stiles, L. A. Thompson Oct 2012

Histological Analysis Of Biological Tissues Using High-Frequency Ultrasound, Kristina Sorensen, Tim Doyle, B. D. Borget, M. Cervantes, H, A. Chappell, B. J. Curtis, M. A. Grover, J. E. Roring, J. E. Stiles, L. A. Thompson

Browse All Undergraduate research

No abstract provided.


Power And Charge Deposition In Multilayer Dielectrics Undergoing Monoenergetic Electron Bombardment, Gregory Wilson, Jr Dennison, Amberly Evans, Justin Dekany Oct 2012

Power And Charge Deposition In Multilayer Dielectrics Undergoing Monoenergetic Electron Bombardment, Gregory Wilson, Jr Dennison, Amberly Evans, Justin Dekany

Presentations

No abstract provided.


High-Frequency Pulsed-Electro-Acoustic (Pea) Measurements For Mapping Charge Distribution, Kristina Sorensen, Lee H. Pearson, Jr Dennison, Timothy E. Doyle, Kent D. Hartley Oct 2012

High-Frequency Pulsed-Electro-Acoustic (Pea) Measurements For Mapping Charge Distribution, Kristina Sorensen, Lee H. Pearson, Jr Dennison, Timothy E. Doyle, Kent D. Hartley

Browse All Undergraduate research

No abstract provided.


Muon Contribution To Cathodoluminescence Tests?, Justin Dekany, Allen Anderson, Jr Dennison Oct 2012

Muon Contribution To Cathodoluminescence Tests?, Justin Dekany, Allen Anderson, Jr Dennison

Posters

Tests of composites incorporating highly disordered insulating materials that were bombarded with low-flux keV electron beams exhibited three distinct forms of light emission: short-duration (<<1 s), high intensity luminous electrostatic discharges between the insulator and ground--termed “arcs”; intermediate-duration (10-100 s), intense surface emissions—termed “flares”; and lower intensity, continuous surface cathodoluminescent “glow”. During long-duration experiments at temperatures <150 K, relatively intense flare events occurred at rates of ~2 per min. Rapid increase in photon emission and electron displacement current were observed, with long exponential decay times >1 min. We propose that the source of the flares is the interactions of high energy muons—of cosmic ray origin—with the highly-charged insulating components of the composite materials, which trigger avalanche electrostatic discharge and subsequent recharging along with concomitant light emission. We review evidence from the insulator conductivity at low temperatures, the rates and magnitude of surface charging, the flare frequency, and the magnitude and time-dependence of currents and light emission with regard to ...


Space Impact Ejecta Model Of Micrometeoroid Collision On Misse-6, Kelby T. Peterson, Jr Dennison Oct 2012

Space Impact Ejecta Model Of Micrometeoroid Collision On Misse-6, Kelby T. Peterson, Jr Dennison

Presentations

No abstract provided.


Muon Contribution To Cathodoluminescence Tests?, Justin Dekany, Allen Andersen, Jr Dennison Oct 2012

Muon Contribution To Cathodoluminescence Tests?, Justin Dekany, Allen Andersen, Jr Dennison

Presentations

Tests of composites incorporating highly disordered insulating materials that were bombarded with low-flux keV electron beams exhibited three distinct forms of light emission: short-duration (<<1 s), high intensity luminous electrostatic discharges between the insulator and ground--termed “arcs”; intermediate-duration (10-100 s), intense surface emissions—termed “flares”; and lower intensity, continuous surface cathodoluminescent “glow”. During long-duration experiments at temperatures <150 K, relatively intense flare events occurred at rates of ~2 per min. Rapid increase in photon emission and electron displacement current were observed, with long exponential decay times >1 min. We propose that the source of the flares is the interactions of high energy muons—of cosmic ray origin—with the highly-charged insulating components of the composite materials, which trigger avalanche electrostatic discharge and subsequent recharging along with concomitant light emission. We review evidence from the insulator conductivity at low temperatures, the rates and magnitude of surface charging, the flare frequency, and the magnitude and time-dependence of currents and light emission with regard to ...


Space Impact Ejecta Model Of Micrometeoroid Collision On Misse-6, Kelby T. Peterson, Jr Dennison Oct 2012

Space Impact Ejecta Model Of Micrometeoroid Collision On Misse-6, Kelby T. Peterson, Jr Dennison

Presentations

The Utah State University SUSpECS project was a unique student experiment that allowed for pre- and post-flight analysis of various materials used in space-component design. Approximately 180 material samples were flown on MISSE-6 and spent 18 months suspended off the side of the International Space Station, which were returned in pristine condition. This presentation focuses on the most intriguing sample, a thin film of polyethylene terephthalate (PET) MylarTM coated with Vapor Deposited Aluminum (VDA). Samples that were part of the Materials International Space Station Experiment (MISSE) experienced diverse effects whilst exposed to the space environment. This sample in particular ...


Short Period Gravity Waves In The Arctic Atmosphere Over Alaska, Michael Negale, Kim Nielsen, Michael J. Taylor, Britta Irving, Richard Collins Oct 2012

Short Period Gravity Waves In The Arctic Atmosphere Over Alaska, Michael Negale, Kim Nielsen, Michael J. Taylor, Britta Irving, Richard Collins

Physics Student Research

The propagation nature and sources of short-period gravity waves have been studied extensively at low and mid-latitudes, while their extent and nature at the polar regions are less known. During the last decade, observations from select sites on the Antarctic continent have revealed a significant presence of these waves over the southern Polar Region as well as shown unexpected dynamical behavior. In contrast, observations over the Arctic region are few and the dynamical behavior is unknown. A recent project was initiated in January 2011 to investigate the presence and dynamics of these waves over interior Alaska. This site provides an ...


Power And Charge Deposition In Multilayer Dielectrics Undergoing Monoenergetic Electron Bombardment, Gregory Wilson, Jr Dennison, Amberly Evans Jensen, Justin Dekany Oct 2012

Power And Charge Deposition In Multilayer Dielectrics Undergoing Monoenergetic Electron Bombardment, Gregory Wilson, Jr Dennison, Amberly Evans Jensen, Justin Dekany

Presentations

No abstract provided.


Space Impact Ejecta Model Of Micrometeoroid Collision On Misse-6, Kelby Peterson, Jr Dennison Oct 2012

Space Impact Ejecta Model Of Micrometeoroid Collision On Misse-6, Kelby Peterson, Jr Dennison

Presentations

No abstract provided.


Electrostatic Discharge Properties Of Fused Silica Coatings, Allen Andersen, Charles Sim, Jr Dennison Oct 2012

Electrostatic Discharge Properties Of Fused Silica Coatings, Allen Andersen, Charles Sim, Jr Dennison

Graduate Student Posters

The electric field value at which electrostatic discharge (ESD) occurs was studied for thin coatings of fused silica (highly disordered SiO2/SiOx) on conductive substrates, such as those encountered as optical coatings and in Si microfabrication. The electrostatic breakdown field was determined using an increasing voltage, while monitoring the leakage current. A simple parallel-plate capacitor geometry was used, under medium vacuum and at temperatures down to ~150 K using a liquid N2 reservoir. The breakdown field, pre-breakdown arcing and I-V curves for fused silica samples are compared for ~60 nm and ~80 μm thick, room and low temperature, and untreated ...


Velocity Plateaus In Traveling-Wave Electrophoresis, R. Correll, Boyd F. Edwards Oct 2012

Velocity Plateaus In Traveling-Wave Electrophoresis, R. Correll, Boyd F. Edwards

All Physics Faculty Publications

One-dimensional models are used to study traveling-wave electrophoresis, a tunable method for separating charged analytes. A traveling-electrode model reveals the mechanism for longitudinal oscillations. A stationary-electrode model explains the origin of mode-locked plateaus in the average velocity, predicts devil's staircases with nested Farey sequences, and reduces to a continuum sinusoidal model in the high electrode-density limit. © 2012 American Physical Society.


Histological Analysis Of Biological Tissues Using High-Frequency Ultrasound, Kristina Sorensen, Timothy Doyle, Brett D. Boret, Monica Cervantes, J. Andrew Chappell, Bradley J. Curtis, Matthew A. Grover, Janeese E. Stiles, Laurel A. Thompson Oct 2012

Histological Analysis Of Biological Tissues Using High-Frequency Ultrasound, Kristina Sorensen, Timothy Doyle, Brett D. Boret, Monica Cervantes, J. Andrew Chappell, Bradley J. Curtis, Matthew A. Grover, Janeese E. Stiles, Laurel A. Thompson

Browse All Undergraduate research

No abstract provided.


Electron Beam Induced Luminescence Of Sio2 Optical Coatings, Jr Dennison, Amberly Evans, Gregory Wilson, Justin Dekany, Charles W. Bowers, Robert Meloy Oct 2012

Electron Beam Induced Luminescence Of Sio2 Optical Coatings, Jr Dennison, Amberly Evans, Gregory Wilson, Justin Dekany, Charles W. Bowers, Robert Meloy

All Physics Faculty Presentations

Optical coatings of disordered thin film SiO2/SiOx dielectric samples on reflective metal substrates exhibited cathodoluminescence under electron beam irradiation. Measurements of the absolute radiance and emission spectra as functions of incident electron energy, flux and power over a range of sample temperatures are reported. Radiance reached a saturation plateau at high incident electron power. Well below saturation radiance scaled with deposited power, that is linearly with incident power for lower-energy non-penetrating electrons and decreasing with increasing energy for penetrating radiation. Four bands were observed in spectral measurements from 300 nm to 1000 nm. Changes in peak intensity and shifts ...


How To Create A Two-Component Spinor, Charles G. Torre Oct 2012

How To Create A Two-Component Spinor, Charles G. Torre

How to... in 10 minutes or less

Let (M, g) be a spacetime, i.e., a 4-dimensional manifold M and Lorentz signature metric g. The key ingredients needed for constructing spinor fields on the spacetime are: a complex vector bundle E -> M ; an orthonormal frame on TM ; and a solder form relating sections of E to sections of TM (and tensor products thereof). We show how to create a two-component spinor field on the Schwarzschild spacetime using the DifferentialGeometry package in Maple. PDF and Maple worksheets can be downloaded from the links below.


Electron Induced Charging And Arcing Of Multilayered Dielectric Materials, Jr Dennison, Gregory Wilson, Amberly Evans, Justin Dekany Oct 2012

Electron Induced Charging And Arcing Of Multilayered Dielectric Materials, Jr Dennison, Gregory Wilson, Amberly Evans, Justin Dekany

All Physics Faculty Presentations

Measurements of the charge distribution in electron-bombarded, thin-film, multilayered dielectric samples showed that charging of multilayered materials evolves with time and is highly dependent on incident energy; this is driven by electron penetration depth, electron emission and material conductivity. Based on the net surface potential’s dependence on beam current, electron range, electron emission and conductivity, measurements of the surface potential, displacement current and beam energy allow the charge distribution to be inferred. To take these measurements, a thin-film disordered SiO2 structure with a conductive middle layer was charged using 200 eV and 5 keV electron beams with regular 15 ...


Electron Beam Induced Luminescence Of Sio2 Optical Coatings, Jr Dennison, Amberly Evans, Gregory Wilson, Charles W. Bowers, Robert Meloy Oct 2012

Electron Beam Induced Luminescence Of Sio2 Optical Coatings, Jr Dennison, Amberly Evans, Gregory Wilson, Charles W. Bowers, Robert Meloy

All Physics Faculty Publications

Optical coatings of disordered thin film SiO2/SiOx dielectric samples on reflective metal substrates exhibited cathodoluminescence under electron beam irradiation. Measurements of the absolute radiance and emission spectra as functions of incident electron energy, flux and power over a range of sample temperatures are reported. Radiance reached a saturation plateau at high incident electron power. Well below saturation radiance scaled with deposited power, that is linearly with incident power for lower-energy non-penetrating electrons and decreasing with increasing energy for penetrating radiation. Four bands were observed in spectral measurements from 300 nm to 1000 nm. Changes in peak intensity and shifts ...


Cedar Electrodynamics Thermosphere Ionosphere (Eti) Challenge For Systematic Assessment Of Ionosphere/Thermosphere Models: Electron Density, Neutral Density, Nmf2, And Hmf2 Using Space Based Observations, J. S. Shim, M. Kuznetsova, L. Rastätter, D. Bilitza, L. Butala, M. Emery, B. Foster, T. J. Fuller-Rowell, J. Huba, A. J. Mannucci, X. Pi, A. Ridley, Ludger Scherliess, Jan J. Sojka, P. Stephens, D. C. Thompson, D. Weimer, Lie Zhu, E. Sutton Oct 2012

Cedar Electrodynamics Thermosphere Ionosphere (Eti) Challenge For Systematic Assessment Of Ionosphere/Thermosphere Models: Electron Density, Neutral Density, Nmf2, And Hmf2 Using Space Based Observations, J. S. Shim, M. Kuznetsova, L. Rastätter, D. Bilitza, L. Butala, M. Emery, B. Foster, T. J. Fuller-Rowell, J. Huba, A. J. Mannucci, X. Pi, A. Ridley, Ludger Scherliess, Jan J. Sojka, P. Stephens, D. C. Thompson, D. Weimer, Lie Zhu, E. Sutton

All Physics Faculty Publications

In an effort to quantitatively assess the current capabilities of Ionosphere/Thermosphere (IT) models, an IT model validation study using metrics was performed. This study is a main part of the CEDAR Electrodynamics Thermosphere Ionosphere (ETI) Challenge, which was initiated at the CEDAR workshop in 2009 to better comprehend strengths and weaknesses of models in predicting the IT system, and to trace improvements in ionospheric/thermospheric specification and forecast. For the challenge, two strong geomagnetic storms, four moderate storms, and three quiet time intervals were selected. For the selected events, we obtained four scores (i.e., RMS error, prediction efficiency ...