| Effect of Diurnal Convection on Trapped Thermal Plasma in the Outer Plasmasphere |
18 APR 97 |
16 pages |
| Authors:
M. A. Reynolds; G. Ganguli; J. A. Fedder; D. J. Melendez-Alvira; NAVAL RESEARCH LAB WASHINGTON DC BEAM PHYSICS BRANCH
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 | A kinetic, multi species model of the plasmasphere is constructed which includes the effect of convection and corotation electric fields on trapped particles in drifting flux tubes. The resulting morphology of the outer plasmasphere is significantly different from that obtained using the assumption of diffusive equilibrium. The difference is due primarily to the contraction and expansion of the region of phase space accessible to the trapped particles, and has implications ... |
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| Preliminary Study of the Dynamics of High Latitude Nuclear Plumes |
21 JUL 88 |
22 pages |
| Authors:
J. A. Fedder; J. G. Lyon; NAVAL RESEARCH LAB WASHINGTON DC
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| This memorandum reports the first results of a preliminary study of the late time behavior of a HANE plasma plume at high-latitude and its interaction with the dynamic plasma processes existing there. The plume is modeled as a region of extremely high ionospheric conductivity. The results demonstrate that he HANE plasma conductivity enhancement polarizes so as to exclude the high velocity plasma convection and therefore does not take an active ... |
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| Approximate Analytical Formulae for Electron Density and Collision Frequency in the Natural and Nuclear-Disturbed Ionosphere and Inner Magnetosphere |
22 FEB 88 |
27 pages |
| Authors:
M. J. Keskinen; J. A. Fedder; NAVAL RESEARCH LAB WASHINGTON DC
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| The phenomenological models of global electron density for the natural ionosphere of Ching and Chiu (1973) and Chiu (1975) have been extended to both lower (60 km) and higher (36,000 km) altitudes. Computer simulations of a high altitude nuclear explosion are analyzed to develop a phenomenological model of electron density. Approximate analytical formulae for electron density and associated electron collision frequency in both the natural and nuclear- distributed near earth ... |
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| Nonlinear Evolution of the Kelvin-Helmholtz Instability in the High Latitude Ionosphere |
21 DEC 87 |
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| Authors:
M. J. Keskinen; H. G. Mitchell; J. A. Fedder; P. Satyanarayana; S. T. Zalesak; NAVAL RESEARCH LAB WASHINGTON DC
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 | The nonlinear evolution of the electrostatic Kelvin Helmholtz instability, resulting from velocity-sheared plasma flows perpendicular to an ambient magnetic field, has been studied including Pedersen conductivity effects (i.e., ion-neutral collisions). The Kelvin Helmholtz instability develops in a distinctly different manner in the nonlinear regime with Pedersen coupling than without it. Specifically, the Pedersen coupling effects, in conjunction with a neutral wind and density gradient, (1) result in an increased time ... |
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| The Solar Wind-Magnetosphere-Ionosphere Current-Voltage Relationship |
29 JUL 87 |
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| Authors:
J. A. Fedder; J. G. Lyon; NAVAL RESEARCH LAB WASHINGTON DC
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| The nature of the solar wind-magnetosphere-ionosphere (SW-M-I) coupling has been a subject of intense study and scientific interest. We report results from a numerical simulation of the SW-M-I system which shed light on the physics and behavior of the controlling processes. The current-voltage relationship is characteristic of a magneto-hydrodynamic dynamo with a load operating near short circuit conditions. The operation of the dynamo, its location with respect to the magnetosphere, ... |
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| Transverse Motion of High Speed Barium Clouds in the Ionosphere |
18 SEP 85 |
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| Authors:
H. G. Mitchell; J. A. Fedder; J. D. Huba; S. T. Zalesak; NAVAL RESEARCH LAB WASHINGTON DC
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| Simulation results, based on a field-line-integrated, 2D, electrostatic model, are presented for the motion of a barium cloud injected transverse to the geomagnetic field in the ionosphere at high speeds. It is found that the gross evolution of injected plasma clouds depends sensitively on the initial conditions, as well as the nature of the background coupling. For a massive (M sub O = approx 10 kg), orbital (V sub O ... |
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| A Simulation of High Latitude F-Layer Instabilities in the Presence of Magnetosphere-Ionosphere Coupling |
08 JUL 85 |
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| Authors:
H. G. Mitchell Jr.; J. A. Fedder; M. J. Keskinen; S. T. Zalesak; NAVAL RESEARCH LAB WASHINGTON DC
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| A magnetic-field-line-integrated model of plasma interchange instabilities is developed for the high latitude ionosphere including magnetospheric coupling effects. We show that primary magnetosphere-ionosphere coupling effect is to incorporate the inertia of the magnetospheric plasma in the analysis. As a specific example, we present the first simulation of the E x B instability in the inertial regime, i.e., nu sub i > omega. Our results show that striations produced in the ... |
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| Cheyenne Mountain Late Time Simulation Results |
07 JUN 85 |
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| Authors:
K. Hain; G. Hain; J. A. Fedder; NAVAL RESEARCH LAB WASHINGTON DC
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| In this report we present results for the late time evolution of the Cheyenne Mountain nuclear explosion scenario. Results are presented from both the DEMAG simulation code and the MELT simulation code. The results are compared and the differences between them are explained. We conclude that the simulation results are in good agreement. Keywords: HANE (High Altitude Nuclear Explosions) ; Nuclear weapons phenomenology; Nuclear explosion simulation; Late-time electrostatic codes. ... |
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| Region 1 Birkeland Currents from a Global MHD Simulation of the Magnetosphere |
28 SEP 1984 |
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| Authors:
J. A. Fedder; J. G. Lyon; NAVAL RESEARCH LAB WASHINGTON DC
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| The study of large scale geomagnetic field aligned currents, which couple the dynamics of the magnetosphere and the high latitude ionosphere, has been an area of intense research interest in recent years. These currents, first postulated by Birkeland (1908) to be responsible for geomagnetic activity and auroral phenomena in the polar regions, were first observed in the 1970's by Arnoldy, Zmuda and Armstrong and Sugiura and have now been extensively ... |
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| Finite Temperature Effects on the Evolution of Ionospheric Barium Clouds in the Presence of a Conducting Background Ionosphere |
24 JUL 1984 |
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| Authors:
S. T. Zalesak; P. K. Chaturvedi; S. L. Ossakow; J. A. Fedder; NAVAL RESEARCH LAB WASHINGTON DC
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| We show that under realistic ionospheric conditions, barium ion clouds hundreds of meters in diameter can be long-lived, quasi-stable, nonbifurcating structures. These structures may resemble 'tadpoles,' with a dense head, steep density gradients at the front, and a long, less dense tail. We assume that these structures are the final products of the recursive bifurcation of a considerably larger barium ion cloud, i.e., striations. The realistic ionospheric conditions to which ... |
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| MHD (Magnetohydrodynamic) Simulation of a Comet Magnetosphere |
12 APR 1984 |
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| Authors:
J. A. Fedder; S. H. Brecht; J. G. Lyon; NAVAL RESEARCH LAB WASHINGTON DC
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| This paper presents results of a numerical magnetohydrodynamic simulation of the interaction of the solar wind with a comet. It states that for a steady solar wind and interplanetary magnetic field (IMF) the cometary plasma has a distinctive structure; a spheroidal head and a long ribbon-like tail. Rotational discontinuities in the IMF lead to changes in the tail structure. It is shown how these effects occur and describe ray-like structures ... |
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| Fast Collisionless Tearing in an Anisotropic Neutral Sheet |
06 FEB 1984 |
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| Authors:
J. Chen; P. J. Palmadesso; J. A. Fedder; J. G. Lyon; NAVAL RESEARCH LAB WASHINGTON DC
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| This document studies the collisionless tearing mode in a neutral sheet in the presence of ion temperature anisotorpy using Vlasov description for both ions and electrons. |
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| Numerical Simulation of a Possible Freezing and Sheet Formation Mechanism for Barium Cloud Striations |
25 OCT 1982 |
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| Authors:
S. T. Zalesak; J. A. Fedder; S. L. Ossakow; NAVAL RESEARCH LAB WASHINGTON DC
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| Presented is a possible mechanism for the freezing, or apparent freezing of barium cloud striations and for the formation of long thin sheets of barium on the leading edge of the cloud. The essence of the model is that the finite Pedersen mobility of the barium ions allows them to separate from the electron cloud. The barium is replaced in the electron cloud by the ions constituting the ambient ionosphere, ... |
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| Conductivity Formulas for the Disturbed Ionosphere. |
04 SEP 1980 |
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| Authors:
J. A. Fedder; NAVAL RESEARCH LAB WASHINGTON DC
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| Conductivity formulas are presented for the disturbed ionosphere. These formulas are recommended for use in HANE simulation studies and for other disturbed ionospheric conditions. |
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| Structuring of Collisionless, High Velocity Ion Clouds. |
04 SEP 1980 |
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| Authors:
J. A. Fedder; NAVAL RESEARCH LAB WASHINGTON DC
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| The stability of high velocity ion clouds was studied in the ionosphere-magnetosphere. We derive the instability growth rate; show that the growth is very fast; and present our conclusions. |
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| Transport Techniques for Describing Scattering and Energy Deposition of Energetic Auroral Electrons. |
SEP 1975 |
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| Authors:
D. J. Strickland; D. L. Book; T. P. Coffey; J. A. Fedder; NAVAL RESEARCH LAB WASHINGTON D C
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| Auroral electron scattering and energy loss are calculated using for the first time a multi-angle equation of transfer at all energies. The results are compared with those obtained using a Fokker-Planck equation. Both equations have been solved in terms of their eigensolutions. The equation of transfer has also been solved by numerical integration. Fokker-Planck solutions agree well with equation-of-transfer solutions above 3 keV but deviate increasingly at lower energies. A ... |
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| Auroral Birkeland Currents and Anomalous Resistance. |
JAN 1975 |
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| Authors:
J. A. Fedder; J. H. Orens; NAVAL RESEARCH LAB WASHINGTON D C
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| Presented are results from an auroral arc model which illustrate the physical relationship between the auroral Birkeland currents and an assumed anomalous resistance along the geomagnetic field. It is shown that the distribution of the Birkeland current is very sensitive to the spatial form of the resistance function. It is also observed that for a variety of resistance functions the auroral field distribution remains essentially unchanged. |
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| Ionospheric Conductance for Sub-Auroral Latitudes at Equinox Twilight. |
NOV 1974 |
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| Authors:
J. A. Fedder; S. L. Ossakow; NAVAL RESEARCH LAB WASHINGTON D C
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| In this note, ionospheric conductivities for electric currents perpendicular to the geomagnetic field are presented. The conductivities have been computed for sub-auroral latitudes for spring and autumn twilight conditions to aid in planning and simulation of the Defense Nuclear Agency-sponsored 1975 barium cloud releases in Alaska. |
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