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NASA NTRS1985

Study of storm time fluxes of heavy ions

Ion composition data sets from Lockheed instruments on a variety of spacecraft were used in combination with each other and with data from other instruments to address a variety of problems regarding plasma sources, energization and transport within the magnetosphere. The availability of data from several differing orbits has given a highly flexible approach to attacking the continually evolving questions of magnetospheric physics. This approach is very successful and should be continued in the future.

Sharp, R. D.↗

NASA NTRS1985

Investigation of the dayside boundary region of the magnetosphere

The region near the dayside boundary of the magnetosphere is of particular interest mainly because it is the most likely site for solar wind energy transfer. Exactly where and how this transfer occurs is one of the basic problems of magnetospheric physics. The global nature of the energy transfer is addressed in this research. In order to test whether energy transfer affects the large scale plasma flow in the magnetosheath, global properties of the magnetosheath were analyzed and compared to models with no energy transfer. Also, global models of merging sites on the magnetopause were modeled with the aid of the magnetosheath models. Since energy transfer and intrinsic magnetosheath properties depend upon the orientation of the interplanetary magnetic field (IMF), it was essential to have an IMF monitor for these studies. In the course of using ISEE 3 in this role, statistical studies were performed to test the accuracy of using data from an orbit so far upstream. Global properties of the magnetosheath energetic ion population, magnetic field strength and orientation, and flow pattern, determined with ISEE data are summarized.

Crooker, N.↗

NASA NTRS1987

Processes associated with the plasma sheet boundary layer

The plasma sheet boundary is an important region of energy and mass transfer in the magnetotail. It is probably formed by energized ions ejected from the cross-tail current sheet. Processes associated with the boundary layer are important to many areas of magnetospheric physics. These areas include energetic particles, plasma sheet sources, auroral precipitation, field-aligned currents and discrete auroral arcs, and substorm initiation.

Lyons, L. R.↗

NASA NTRS1987

Plasma instabilities in the terrestrial magnetosphere - A review of recent theoretical research

This paper reviews recent theoretical research on plasma instabilities in the terrestrial magnetosphere. This paper is organized with respect to particle free energies: electron-ion currents, electron beams, ion beams, electron anisotropies and ion anisotropies are successively considered. For each free energy, the associated instability properties are summarized, and their applications to magnetospheric physics are briefly described. Theory and simulations which have established close correlations with observations are emphasized.

Gary, S. Peter↗

NASA NTRS1989

Overview of the National Aeronautics and Space Administration tether activities

NASA research concerning the use of tethers in space is reviewed, including joint research with the Italian Space Agency. Tether applications under consideration are described, such as a tethered fuel depot and a tethered gravity laboratory platform for the Space Station, providing artificial gravity to and from Mars, payload recovery and waste management, aerothermodynamic magnetospheric physics, and electrodynamic propulsion, braking, and power generation for the Space Shuttle. Also, tether flight demonstrations are examined, including the Small Expendable Deployer System, the Get-Away Tether Experiment, the Tether Elevator Crawler System, and the Kinetic Isolation Tether Experiment.

Penzo, Paul A.↗

NASA NTRS1989

Fast Fermi acceleration in the plasma sheet boundary layer

A longstanding question in the field of magnetospheric physics is the source of the energetic particles which are commonly observed along the plasma-sheet boundary layer (PSBL). Several models have been suggested for the acceleration of these particles. Here, a means is suggested by which the fast Fermi acceleration mechanism (Wu, 1984) can accelerate electrons at the plasma sheet and perhaps account for some of the observations. In this scheme, a localized hydromagnetic disturbance propagating through the tail lobe region impinges upon the PSBL, deforming it and displacing it in toward the central plasma sheet. The boundary layer can then act like a moving magnetic mirror. If the disturbance is propagating nearly perpendicular to the layer, then its velocity projected parallel to the layer (and the magnetic field) can be very large, resulting in significant acceleration of reflected particles.

Wu, C. S.↗

NASA NTRS1991

Plasma motions in planetary magnetospheres

Interplanetary space is pervaded by a supersonic 'solar wind' plasma; five planets, in addition to the earth, have magnetic fields of sufficient strength to form the cometlike cavities called 'magnetospheres'. Comparative studies of these structures have indicated the specific environmental factor that can result in dramatic differences in the behavior of any pair of magnetospheres. Although planetary magnetospheres are large enough to serve as laboratories for in situ study of cosmic plasma and magnetic field behavior effects on particle acceleration and EM emission, much work remains to be done toward relating magnetospheric physics results to the study of remote astrophysical plasmas.

Hill, T. W.↗

NASA NTRS1991

Ground-based observations of comets, the Jupiter plasma Torus, and Io

Aspects of cometary and magnetospheric physics were investigated by means of ground-based astronomical spectroscopy. High-throughput, dual-etalon Fabry-Perot spectrometers were used to obtain very high resolution spectra of atomic, molecular, and ionic emission lines from the diffuse gases and plasmas associated with comets and the Jupiter plasma torus. The Fabry-Perot spectrometers were also used with a charge coupled device (CCD) camera to obtain images of these extended emission sources in individual spectral lines at high spectral resolution. A new program using the McMath solar-stellar spectrograph to observe emission lines from Io was recently initiated. The McMath spectrograph has a high resolution mode which allows the detection of narrow, relatively faint emission lines superimposed on Io's reflected solar spectrum.

Scherb, Frank↗

NASA NTRS1994

A Space and Atmospheric Visualization Science System

SAVS (a Space and Atmospheric Visualization Science system) is an integrated system with user-friendly functionality that employs a 'push-button' software environment that mimics the logical scientific processes in data acquisition, reduction, analysis, and visualization. All of this is accomplished without requiring a detailed understanding of the methods, networks, and modules that link the tools and effectively execute the functions. This report describes SAVS and its components, followed by several applications based on generic research interests in interplanetary and magnetospheric physics (IMP/ISTP), active experiments in space (CRRES), and mission planning focused on the earth's thermospheric, ionospheric, and mesospheric domains (TIMED). The final chapters provide a user-oriented description of interface functionalities, hands-on operations, and customized modules, with details of the primary modules presented in the appendices. The overall intent of the report is to reflect the accomplishments of the three-year development effort and to introduce potential users to the power and utility of the integrated data acquisition, analysis, and visualization system.

Szuszczewicz, E. P.↗

NASA NTRS1995

SAVS: A Space and Atmospheric Visualization Science system

The research environment faced by space and atmospheric scientists in the 1990s is characterized by unprecedented volumes of new data, by ever-increasing repositories of unexploited mission files, and by the widespread use of empirical and large-scale computational models needed for the synthesis of understanding across data sets and discipline boundaries. The effective analysis and interpretation of such massive amounts of information have become the subjects of legitimate concern. With SAVS (a Space and Atmospheric Visualization Science System), we address these issues by creating a 'push-button' software environment that mimics the logical scientific processes in data acquisition, reduction, and analysis without requiring a detailed understanding of the methods, networks, and modules that link the tools and effectively execute the functions. SAVS provides (1) a customizable framework for accessing a powerful set of visualization tools based on the popular AVS visualization software with hooks to PV-Wave and access to Khoros modules, (2) a set of mathematical and statistical tools, (3) an extensible library of discipline-specific functions and models (e.g., MSIS, IRI, Feldstein Oval, IGRF, satellite tracking with CADRE-3, etc.), and (4) capabilities for local and remote data base access. The system treats scalar, vector, and image data, and runs on most common Unix workstations. We present a description of SAVS and its components, followed by several applications based on generic research interests in interplanetary and magnetospheric physics (IMP/ISTP), active experiments in space (CRRES), and mission planning focused on the Earth's thermospheric, ionospheric, and mesospheric domains (TIMED).

Szuszczewicz, E. P.↗

NASA NTRS1998

IMAGE Mission Science

Simultaneous, global measurement of major magnetospheric plasma systems will be performed for the first time with the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) Mission. The ring current, plasmasphere, and auroral systems will be imaged using energetic neutral and ultraviolet cameras. Quantitative remote measurement of the magnetosheath, plasmaspheric, and magnetospheric densities will be obtained through radio sounding by the Radio Plasma Imager. The IMAGE Mission will open a new era in global magnetospheric physics, while bringing with it new challenges in data analysis. An overview of the IMAGE Theory and Modeling team efforts will be presented, including the state of development of Internet tools that will be available to the science community for access and analysis of IMAGE observations.

Gallagher, D. L.↗

NASA NTRS1998

Magnetospheric Constellation and Tomography Mission Concept

We describe the basic principles, instrumentation, and feasibility of a multi-satellite mission that combines in situ observations of plasma and electromagnetic fields with radio tomography imaging. We show that a 16-satellite radio tomography experiment can produce two-dimensional images of plasma density in the earth's magnetosphere at sufficient spatial (1/2 R(sub E)) and temporal (approximately 10s) resolution to address key problems of magnetospheric physics. The same mission can incorporate electron and ion analyzers, magnetometers, and electric field instruments on the same spacecraft. We suggest that the large-scale images are more valuable when combined with in situ observations, supporting an unambiguous interpretation of the in situ data and an investigation of the interdependence of small- and large-scale plasma processes.

Ergun, R. E.↗

NASA NTRS2004

Unresolved Issues With Inner Magnetosphere-Ionosphere Coupling

Dipolarization and the release of stored magnetic energy is strongly evident in the energized plasma sheet electrons and ions injected earthward from the magnetotail. While some of these plasma are presumed lost into the dayside magnetosheath, much of the energy is dissipated into the ionosphere through electric currents, through collisions into low energy plasma, and into plasma waves, which then go on to heat and energize plasma of the inner magnetosphere. Many mechanisms for the transfer of energy and the consequences to inner magnetospheric plasma populations have been proposed. The sophistication of theoretical models to represent the interdependencies between plasma populations is rapidly increasing. However without the restraint and reality imposed on theory by relevant measurements, the degree to which specific mechanisms participate in the exchange of energy as a function of location and time cannot be known. ORBITALS offers this capability. Some of the outstanding problems in inner magnetospheric physics and the opportunities presented by the ORBITAL concept to solve problems will be discussed.

Gallagher, D. L.↗

NASA NTRS2006

Self-Consistent Ring Current Modeling with Propagating Electromagnetic Ion Cyclotron Waves in the Presence of Heavy Ions

The self-consistent treatment of the RC ion dynamics and EMIC waves, which are thought to exert important influences on the ion dynamical evolution, is an important missing element in our understanding of the storm-and recovery-time ring current evolution. Under certain conditions, relativistic electrons, with energies 21 MeV, can be removed from the outer radiation belt by EMIC wave scattering during a magnetic storm. That is why the modeling of EMIC waves is critical and timely issue in magnetospheric physics. To describe the RC evolution itself this study uses the ring current-atmosphere interaction model (RAM). RAM solves the gyration and bounce-averaged Boltzmann-Landau equation inside of geosynchronous orbit. Originally developed at the University of Michigan, there are now several branches of this model currently in use as describe by Liemohn namely those at NASA Goddard Space Flight Center This study will generalize the self-consistent theoretical description of RC ions and EMIC waves that has been developed by Khazanov and include the heavy ions and propagation effects of EMIC waves in the global dynamic of self-consistent RC - EMIC waves coupling. The results of our newly developed model that will be presented at GEM meeting, focusing mainly on the dynamic of EMIC waves and comparison of these results with the previous global RC modeling studies devoted to EMIC waves formation. We also discuss RC ion precipitations and wave induced thermal electron fluxes into the ionosphere.

Khazanov, George V.↗

NASA NTRS2006

Self-Consistent Ring Current Modeling with Propagating Electromagnetic Ion Cyclotron Waves in the Presence of Heavy Ions

The self-consistent treatment of the RC ion dynamics and EMlC waves, which are thought to exert important influences on the ion dynamical evolution, is an important missing element in our understanding of the storm-and recovery-time ring current evolution. Under certain conditions, relativistic electrons, with energies greater than or equal to 1 MeV, can be removed from the outer radiation belt by EMlC wave scattering during a magnetic storm (Summers and Thorne, 2003; Albert, 2003). That is why the modeling of EMlC waves is critical and timely issue in magnetospheric physics. This study will generalize the self-consistent theoretical description of RC ions and EMlC waves that has been developed by Khazanov et al. [2002, 2003] and include the heavy ions and propagation effects of EMlC waves in the global dynamic of self-consistent RC - EMlC waves coupling. The results of our newly developed model that will be presented at Huntsville 2006 meeting, focusing mainly on the dynamic of EMlC waves and comparison of these results with the previous global RC modeling studies devoted to EMlC waves formation. We also discuss RC ion precipitations and wave induced thermal electron fluxes into the ionosphere.

Khazanov, G. V.↗

NASA NTRS2006

Self-Consistent Ring Current/Electromagnetic Ion Cyclotron Waves Modeling

The self-consistent treatment of the RC ion dynamics and EMIC waves, which are thought to exert important influences on the ion dynamical evolution, is an important missing element in our understanding of the storm-and recovery-time ring current evolution. For example, the EMlC waves cause the RC decay on a time scale of about one hour or less during the main phase of storms. The oblique EMIC waves damp due to Landau resonance with the thermal plasmaspheric electrons, and subsequent transport of the dissipating wave energy into the ionosphere below causes an ionosphere temperature enhancement. Under certain conditions, relativistic electrons, with energies 21 MeV, can be removed from the outer radiation belt by EMIC wave scattering during a magnetic storm. That is why the modeling of EMIC waves is critical and timely issue in magnetospheric physics. This study will generalize the self-consistent theoretical description of RC ions and EMIC waves that has been developed by Khazanov et al. [2002, 2003] and include the heavy ions and propagation effects of EMIC waves in the global dynamic of self-consistent RC - EMIC waves coupling. The results of our newly developed model that will be presented at the meeting, focusing mainly on the dynamic of EMIC waves and comparison of these results with the previous global RC modeling studies devoted to EMIC waves formation. We also discuss RC ion precipitations and wave induced thermal electron fluxes into the ionosphere.

Khazanov, G. V.↗

NASA NTRS2010

On the Role of Global Magnetic Field Configuration in Affecting Ring Current Dynamics

Plasma and field interaction is one important aspect of inner magnetospheric physics. The magnetic field controls particle motion through gradient, curvature drifts and E cross B drift. In this presentation, we show how the global magnetic field affects dynamics of the ring current through simulations of two moderate geomagnetic storms (20 November 2007 and 8-9 March 2008). Preliminary results of coupling the Comprehensive Ring Current Model (CRCM) with a three-dimensional plasma force balance code (to achieve self-consistency in both E and B fields) indicate that inclusion of self-consistency in B tends to mitigate the intensification of the ring current as other similar coupling efforts have shown. In our approach, self-consistency in the electric field is already an existing capability of the CRCM. The magnetic self-consistency is achieved by computing the three-dimensional magnetic field in force balance with anisotropic ring current ion distributions. We discuss the coupling methodology and its further improvement. In addition, comparative studies by using various magnetic field models will be shown. Simulation results will be put into a global context by analyzing the morphology of the ring current, its anisotropy and characteristics ofthe interconnected region 2 field-aligned currents.

Zheng, Y.↗

NASA NTRS2016

Gamma-Ray Pulsar Light Curves as Probes of Magnetospheric Structure

The large number of gamma-ray pulsars discovered by the Fermi Gamma-Ray Space Telescope since its launch in 2008 dwarfs the handful that were previously known. The variety of observed light curves makes possible a tomography of both the ensemble-averaged field structure and the high-energy emission regions of a pulsar magnetosphere. Fitting the gamma-ray pulsar light curves with model magnetospheres and emission models has revealed that most of the high-energy emission, and the particles acceleration, takes place near or beyond the light cylinder, near the current sheet. As pulsar magnetosphere models become more sophisticated, it is possible to probe magnetic field structure and emission that are self-consistently determined. Light curve modeling will continue to be a powerful tool for constraining the pulsar magnetosphere physics.

Harding, A. K.↗