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Articles 1 - 10 of 10
Full-Text Articles in Physics
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
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 …
Temperature And Electric Field Dependence Of Conduction In Low-Density Polyethylene, John R. Dennison, Jerilyn Brunson
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 …
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
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
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
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
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
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 4f7/2 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
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.
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
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 …
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
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 …