Physics Commons^™

Equatorial F-Region Zonal Plasma Drifts, Bela G. Fejer, E. Kudeki, D. T. Farley

Bela G. Fejer

We have examined in detail the F region plasma drifts measured at Jicamarca, Peru, during 1978–1981, a period of high solar activity, and compared these drifts with Jicamarca data taken during periods of lower activity, as well as with other equatorial zonal neutral wind and plasma drift measurements. The increase in solar activity causes larger nighttime eastward plasma drifts at Jicamarca and delays the morning reversal time from eastward nighttime to westward daytime drifts. The radar data seem to be in good agreement with nighttime neutral wind measurements made by the DE-2 satellite, but are systematically smaller than spaced receiver …

(E,2e) Spectroscopic Investigations Of The Spectral Momentum Densities Of Thin Carbon Films, John Robert Dennison

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

An (e,2e) electron scattering spectrometer has been constructed and used for the first time to investigate the spectral momentum density of the valence bands of a solid target. This technique provides fundamental information about the electronic structure of both crystalline and amorphous solids. The three fundamental quantities, the band structure, electron density of states, and electron momentum distribution can be simultaneously derived from the measured (e,2e) cross section.

A review of single electron and (e,2e) scattering theory is given with an emphasis on scattering from solids. The effects of multiple scattering are discussed and a method of deconvoluting those effects …

Interaction Of The Zonalwinds With The Equatorial Midnight Pressure Bulge In The Earth's Thermosphere: Empiricalevidence Of Momentum Balance, F. A. Herrero, H. G. Mayr, N. W. Spencer, A. E. Hedin, Bela G. Fejer

Bela G. Fejer

A minimum is observed at midnight in the time variation of averaged zonal winds measured in-situ near the equator at an average altitude of about 350 km, and we inquire whether observations of the equatorial midnight pressure bulge are consistent with this feature. The observed zonal wind maintains an eastward direction all night. It increases steadily in the early evening reaching a maximum of about 160 m/s at 2100 hrs local time (LT), dropping to a minimum of about 70 m/s around 2400 LT, then up to about 120 m/s around 0300 LT, decreasing thereafter and turning westward in the …

Analysis Of A Rocket-Borne Resonant Scatter System For Measurement Of Atomic Oxygen, Neil B. Myers

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A computer model has been developed at Utah State University for interpreting the results of a rocket-borne resonant scatter measurement system using 1304 A radiation. Atomic oxygen densities are obtained from 65 to 140 km from three rocket flights. The resolution of the system is < 0.1 km, and considerable structure has been observed. The variety of shapes exhibited by the three profiles suggest a dynamic nature to atomic oxygen density profiles in the lower ionosphere. Maximum densities between 2.6 x 10¹¹ and 1.2 x 10¹² cm^-3 were observed at altitudes between 92 and 95 km.

Safety Evaluation Report Related To The Renewal Of The Operating License For The Triga Training And Research Reactor At The University Of Utah, United States Nuclear Regulatory Commission, Office Of Nuclear Reactor Regulations

Radioactive Materials

This Safety Evaluation Report for the application filed by the University of Utah (UU) for a renewal of operating license R-126 to continue to operate a training and research reactor facility has been prepared by the Office of Nuclear Reactor Regulation of the U.S. Nuclear Regulatory Commission. The facility is owned and operated by the University of Utah and is located on its campus in Salt Lake City, Salt Lake County, Utah. The staff concludes that this training reactor facility can continue to be operated by UU without endangering the health and safety of the public.

Theory Of Spectral Asymmetries And Nonlinear Currentsin The Equatorial Electrojet, E. Kudeki, D. T. Farley, Bela G. Fejer

Bela G. Fejer

The spectral up-down asymmetry of type 1 echoes returned from the equatorial electrojet irregularities is shown to be a consequence of the nonlinear development of the horizontally propagating large scale primary waves which dominate the k spectrum of the electrojet turbulence. The waves reduce the vertical electric polarization field of the electrojet and suffer second harmonic distortion as they grow. These effects together could cause an asymmetry exceeding 20% between the upward and downward components of the relative (to the ions) electron velocity associated with the primary waves. This asymmetry, which changes its direction from day to night as does …

Symmetry Behavior Of The Static Taub Universe: Effect Of Curvature Anisotropy, T. C. Shen, B. L. Hu, D. J. O'Connor

T. -C. Shen

Using the static Taub universe as an example, we study the effect of curvature anisotropy on symmetry breaking of self-interacting scalar field. The one-loop effective potential of a λφ⁴ field with arbitrary coupling (ξ) is computed by ζ-function regularization. It is expressed as a perturbative series in a small anisotropy parameter α measuring the deformation from the spherical Einstein universe with radius of curvature α. This result is used for analyzing the symmetry behavior of such a system as a function of the geometric (α,α) and field (ξ,λ) parameters. The result is also used to address the question of …

Universal Time Dependence Of Nighttime F Region Densities At High Latitudes, O De La Beaujardiere, Vincent B. Wickwar, G Caudal, J Holt, J D. Craven, L A. Frank, L Brace, D Evans, J D. Winningham, R A. Heelis

All Physics Faculty Publications

Coordinated EISCAT, Chatanika, and Millstone Hill incoherent scatter radar observations have revealed that in the auroral zone, the nighttime F region densities vary substantially with the longitude of the observing site: EISCAT’s densities are the largest and Millstone Hill’s are the lowest. The nighttime F region densities measured by the individual radars are not uniform: the regions where the densities are maximum are the so-called “blobs” or “patches” that have been reported previously. The observations are consistent with the hypothesis that the nighttime densities are produced in significant amounts not by particle precipitation, but by solar EUV radiation, and that …

Effect Of The Interplanetary Magnetic Field Y Component On The High‐Latitude Nightside Convection, O. De La Beaujardiere, Vincent B. Wickwar, J D. Kelly, J H. King

All Physics Faculty Publications

Sondrestrom radar observations reveal that the dawn‐dusk (B_y) component of the interplanetary magnetic field (IMF) strongly influences the nightside polar convection. This effect is quite complex. The convection for one orientation of B_y is not the mirror image of the other orientation. A positive B_y (i.e., pointing toward dusk) seems to organize the velocities such that, at all local times, they are predominantly westward within the radar field‐of‐view (≃68°‐to‐82° invariant latitude). Between dusk and midnight, on one such occasion, sunward flow is observed within the polar cap. In the midnight and dawn sectors, when B_{y …}

A Theoretical Study Of The Global F Region For June Solstice, Summer Maximum, And Low Magnetic Activity, Jan Josef Sojka, Robert W. Schunk

All Physics Faculty Publications

We constructed a time-dependent, three-dimensional, multi-ion numerical model of the global ionosphere at F region altitudes. The model takes account of all the processes included in the existing regional models of the ionosphere. The inputs needed for our global model are the neutral temperature, composition, and wind; the magnetospheric and equatorial electric field distributions; the auroral precipitation pattern; the solar EUV spectrum; and a magnetic field model. The model produces ion (NO⁺, O₂⁺, N₂⁺, N⁺, O⁺, He⁺) density distributions as a function of time. For our …

Refilling Of Geosynchronous Flux Tubes As Observed At The Equator By Geos 2, Jan Josef Sojka, G. L. Wrenn

All Physics Faculty Publications

During periods of extended quiet geomagnetic activity the geosynchronous satellite orbit lies inside the plasmasphere. Five such periods were observed by the GEOS 2 satellite. During the initial 48 hours of such periods the equatorial plasma flux tube density increases at 30 to 50 cm⁻³/day. However, on reaching ∼100 cm⁻³ the refilling rate decreases, and refilling is limited. Only when the density reaches ∼100 cm⁻³ do the plasma characteristics and fluctuations appear to be plasmaspheric and the flow predominantly corotational. The “hot outer zone” of the plasmasphere is highly structured in density and temperature when viewed …

Theoretical Study Of Anomalously High F Region Peak Altitudes In The Polar Ionosphere, Jan Josef Sojka, Robert W. Schunk

All Physics Faculty Publications

During the last solar maximum period several observations of anomalously high F region peak altitudes have been made by the high latitude incoherent scatter radars. The observations indicate that there are several distinctive features associated with these high h_mF₂ ionospheric profiles: (1) they are observed near midnight with the plasma flowing out of the polar cap, (2) N_mF₂ ranges from 105 to 106 cm−3, (3) h_mF₂ ranges from 400 to 500 km, (4) below 300 km the profile is devoid of ionization, and (5) the observations are for solar maximum conditions. …