569
569
Jun 1, 2011
06/11
by
Troutman, Patrick A.; Bethke, Kristen; Stillwagen, Fred; Caldwell, Darrell L., Jr.; Manvi, Ram; Strickland, Chris; Krizan, Shawn A
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This paper summarizes the content of a NASA-led study performed to identify revolutionary concepts and supporting technologies for Human Outer Planet Exploration (HOPE). Callisto, the fourth of Jupiter's Galilean moons, was chosen as the destination for the HOPE study. Assumptions for the Callisto mission include a launch year of 2045 or later, a spacecraft capable of transporting humans to and from Callisto in less than five years, and a requirement to support three humans on the surface for a...
Topics: MAGNETIC STORMS, DATA BASES, PLASMA LAYERS, CRRES (SATELLITE), EARTH MAGNETOSPHERE
583
583
May 29, 2011
05/11
by
Mehta, Rabindra D
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Aerodynamics plays a prominent role in the flight of a cricket ball released by a bowler. The main interest is in the fact that the ball can follow a curved flight path that is not always under the control of the bowler. ne basic aerodynamic principles responsible for the nonlinear flight or ''swing'' of a cricket ball were identified several years ago and many papers have been published on the subject. In the last 20 years or so, several experimental investigations have been conducted on...
Topics: EARTH MAGNETOSPHERE, PLASMA LAYERS, LOW COST, LAUNCHING, ECONOMICS, ESTIMATES, FINANCIAL MANAGEMENT
283
283
May 23, 2011
05/11
by
Matthews, K.; Ghez, A. M.; Weinberger, A. J.; Neugebauer, G
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The first diffraction limited, 0.05s resolution, images on the W. M. Keck Telescope have been obtained at a wavelength of 2.2 micrometers. These images were part of an experiment to test the suitability of the Keck Telescope for speckle imaging. In order to conduct this test, it was necessary to modify the pixel scale of the Keck facility Near Infrared Camera (NIRC) to optimally sample the spatial frequencies made available by the Keck telescope. The design and implementation of the external...
Topics: MAGNETIC STORMS, GEOMAGNETIC TAIL, AURORAS, PLASMA LAYERS, MAGNETIC FIELDS, MAGNETOHYDRODYNAMIC...
This grant represented one-year, phase-out funding for the project of the same name (NAG5-9110 to Boston University) to determine precursors and signatures of local substorm onset and how they evolve in the plasma sheet using the Geotail near-Earth database. We report here on two accomplishments: (1) Completion of an examination of plasma velocity signature at times of local onsets in the current disruption (CD) region. (2) Initial investigation into quantification of near-Earth flux-tube...
Topics: NASA Technical Reports Server (NTRS), MAGNETIC STORMS, PLASMA LAYERS, SPACE WEATHER, MODELS, EARTH...
The goal of this project is to determine precursors and signatures of local substorm onset and how they evolve in the plasma sheet using the Geotail near-Earth database. This project is part of an ongoing investigation involving this PI, Nelson Maynard (Mission Research Corporation), and William Burke (AFRL) toward an empirical understanding of the onset and evolution of substorms. The first year began with dissemination of our CRRES findings, which included an invited presentation and major...
Topics: NASA Technical Reports Server (NTRS), MAGNETIC STORMS, DATA BASES, PLASMA LAYERS, CRRES...
This is a systematic attempt to identify and assess near-equatorial, high-eccentricity orbits best suited for studying the Earth's magnetosphere, in particular its most dynamic part, the plasma sheet of the magnetotail. The study was motivated by the design needs of a multi-spacecraft "constellation" mission, stressing low cost, minimal active control and economic launch strategies, and both quantitative and qualitative aspects were investigated. On one hand, by collecting hourly...
Topics: NASA Technical Reports Server (NTRS), EARTH MAGNETOSPHERE, PLASMA LAYERS, LOW COST, LAUNCHING,...
916
916
May 22, 2011
05/11
by
Barker, John L.; Knowles, Dan, Jr; Harnden, Joann M. K.; Montgomery, Harry; Anuta, Paul; Kvaran, Geir; Knight, ED; Bryant, Tom; Mckay, AL; Smid, Jon
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The EOS Moderate Resolution Imaging Spectrometer (MODIS) is being developed by NASA for flight on the Earth Observing System (EOS) series of satellites, the first of which (EOS-AM-1) is scheduled for launch in 1998. This document describes the algorithms and their theoretical basis for the MODIS Level 1B characterization, calibration, and geolocation algorithms which must produce radiometrically, spectrally, and spatially calibrated data with sufficient accuracy so that Global change research...
Topics: CURRENT SHEETS, MATHEMATICAL MODELS, TWILIGHT GLOW, GRADIENTS, INTERNATIONAL SUN EARTH EXPLORER 1,...
The solar photon output, which was once thought to be constant, varies over all time scales from seconds during solar flares to years due to the solar cycle. These solar variations cause significant deviations in the Earth and space environments on similar time scales, such as affecting the atmospheric densities and composition of particular atoms, molecules, and ions in the atmospheres of the Earth and other planets. Presented and discussed will be examples of unprecedented observations from...
Topics: NASA Technical Reports Server (NTRS), PHOTONS, SOLAR OBSERVATORIES, SOLAR SYSTEM, SOLAR ACTIVITY,...
237
237
Jun 2, 2011
06/11
by
Pugel, D. E.; Lakew, B.; Aslam, S.; Wang, L
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This paper examines the effectiveness of Pt/Cr thin film masks for the architecture of monolithic membrane structures in r-plane single crystal sapphire. The development of a pinhole-free Pt/Cr composite mask that is resistant to boiling H2SO4:H3PO4 etchant will lead to the fabrication of smooth sapphire membranes whose surfaces are well-suited for the growth of low-noise high Tc films. In particular, the relationship of thermal annealing conditions on the Pt/Cr composite mask system to: (1)...
Topics: MECHANICAL PROPERTIES, STABILITY, FRACTOGRAPHY, SPRAYED COATINGS, PLASMA LAYERS, ZIRCONIUM OXIDES,...
For nearly 30 years an often-times heated debate has engaged the substorm community: Do substorms begin with the formation of a new reconnection site in the midtail plasma sheet (the Near-Earth Neutral Line model) or do they begin near the transition region between stretched tail and dipolar field lines (the Current Disruption model). The THEMIS mission, with a coordinated suite of five in-situ spacecraft and ground observatories, has greatly extended our understanding of how substorms initiate...
Topics: NASA Technical Reports Server (NTRS), MAGNETIC STORMS, PLASMA LAYERS, ATMOSPHERIC MODELS,...
We have achieved all the goals stated in our grant proposal. Specifically, these include: 1. The understanding of the complexity induced nonlinear spatiotemporal coherent structures and the coexisting propagating modes. 2. The understanding of the intermittent turbulence and energization process of the observed Bursty Bulk Flows (BBF's) in the Earth s magnetotail. 3. The development of "anisotropic three-dimensional complexity" in the plasma sheet due to localized merging and...
Topics: NASA Technical Reports Server (NTRS), SPACE PLASMAS, NONLINEARITY, MAGNETIC FIELD CONFIGURATIONS,...
312
312
May 22, 2011
05/11
by
Bishop, J.; Murchie, S.; Pratt, S.; Mustard, J.; Pieters, C
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Reflectance spectra are presented here for a variety of particulate, ferric-containing analogs to Martian soil (Fe(3)-doped smectites and palagonites) to facilitate interpretation of remotely acquired spectra. The analog spectra were measured under differing environmental conditions to evaluate the influence of exposure history on water content and absorption features due to H2O in these samples. Each of these materials contains structural OH bonded to metal cations, adsorbed H2O, and bound H2O...
Topics: GEOPHYSICS, PLASMA CURRENTS, INTERNATIONAL SUN EARTH EXPLORER 1, PLASMA COMPOSITION, PLASMA LAYERS,...
444
444
May 23, 2011
05/11
by
Schelman, David A.; Jenkins, Phillip P.; Brinker, David J.; Appelbaum, Josep
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Past NASA missions to Mars, Jupiter and the outer planets were powered by radioisotope thermal generators (RTG's). Although these devices proved to be reliable, their high cost and highly toxic radioactive heat source has made them far less desirable for future planetary missions. This has resulted in a renewed search for alternate energy sources, some of them being photovoltaics (PV) and thermo-photovoltaics (TPV). Both of these alternate energy sources convert light/thermal energy directly...
Topics: SOLAR WIND, IONS, INNER RADIATION BELT, GEOMAGNETIC TAIL, SATELLITE INSTRUMENTS, MAGNETICALLY...
This final report describes activities under NASA contract NAS5-31213 to Lockheed Missiles and Space Company. The report covers the entire contract period from 8 May 1991 to 7 Jun. 1994. This is a contract under the NASA Guest Investigator Program for the analysis and interpretation of the combined scientific data from the Hot Plasma Composition Experiment (HPCE) and the Charge Energy Mass (CHEM) spectrometer on the AMPTE/Charge Composition Explorer (CCE) spacecraft. These combined data sets...
Topics: NASA Technical Reports Server (NTRS), HIGH TEMPERATURE PLASMAS, IONS, MAGNETOPAUSE, MAGNETOSHEATH,...
Floating emissive probe plasma potential data are presented over a two-dimensional array of locations in the near Discharge Cathode Assembly (DCA) region of a 30-cm diameter ring-cusp ion thruster. Discharge plasma data are presented with beam extraction at throttling conditions comparable to the NASA TH Levels 8, 12, and 15. The operating conditions of the Extended Life Test (ELT) of the Deep Space One (DS1) flight spare ion engine, where anomalous discharge keeper erosion occurred, were TH 8...
Topics: NASA Technical Reports Server (NTRS), ION PROPULSION, PLASMA POTENTIALS, ION ENGINES, CATHODES,...
The velocity of the first plasma sheet was determined between the electrodes of a pulsed plasma thruster using three measurement techniques: time of flight probe, high speed camera and magnetic field probe. Further, for time of flight probe and magnetic field probe, it was possible to determine the velocity distribution along the electrodes, as the plasma sheet is accelerated. The results from all three techniques are shown, and are compared for one thruster geometry.
Topics: NASA Technical Reports Server (NTRS), HIGH SPEED CAMERAS, VELOCITY MEASUREMENT, PLASMA LAYERS,...
A simple circuit is applied to the energizing of auroral particles, to solar flares, and to intergalactic double radio sources. Application to the heliospheric current systems leads to the prediction of two double layers on the Sun's axis which may give radiations detectable from Earth. Double layers in space should be classified as a new type of celestial object. It is suggested that X-ray and gamma-ray bursts may be due to exploding double layers (although annihilation is an alternative...
Topics: NASA Technical Reports Server (NTRS), ASTRONOMICAL MODELS, CIRCUITS, COSMIC PLASMA, PLASMA LAYERS,...
A fundamental goal of magnetospheric physics is to understand the transport of plasma through the solar wind-magnetosphere-ionosphere system. To attain such an understanding, we must determine the sources of the plasma, the trajectories of the particles through the magnetospheric electric and magnetic fields to the point of observation, and the acceleration processes they undergo enroute. This study employed plasma distributions observed in the near-Earth plasma sheet by Interball and Geotail...
Topics: NASA Technical Reports Server (NTRS), PLASMA LAYERS, PLASMAS (PHYSICS), SOLAR WIND,...
During this reporting period effort continued in the areas: (1) understanding the mechanisms responsible for substorm onset, and (2) application of a fundamental description of field-aligned currents and parallel electric fields to the plasma-sheet boundary layer.
Topics: NASA Technical Reports Server (NTRS), MAGNETIC STORMS, FIELD ALIGNED CURRENTS, ELECTRIC FIELDS,...
The application of techniques of the singular perturbation theory to the analysis of warm plasma is discussed. Typically, the cold plasma model can be applied over wide ranges of parameters and only over narrow ranges forming so-called boundary layers is the warm plasma model used. Simplified equations can be used and the solutions matched on both sides of the layer's boundary. Simple examples to illustrate the solution are presented. The analysis confirms that some results are highly sensitive...
Topics: NASA Technical Reports Server (NTRS), PLASMA DIAGNOSTICS, PLASMA DYNAMICS, PLASMA LAYERS, THERMAL...
Double layers form along auroral field lines in the Earth's magnetosphere. They form in order to maintain current continuity in the ionosphere in the presence of a magnetospheric electric field E with nabla x E is not equal to 0. Features which govern the formation of the double layers are: (1) the divergence of E, (2) the conductivity of the ionosphere, and (3) the current-voltage characteristics of auroral magnetic field lines. Astrophysical situations where nabla x E is not equal to 0 is...
Topics: NASA Technical Reports Server (NTRS), AURORAS, EARTH MAGNETOSPHERE, ELECTRIC FIELDS, PLASMA LAYERS,...
There has been considerable recent interest in the relationship between the cross-tail magnetic field component B(sub y) and tail dynamics. The purpose of this paper is to give an overall description of the penetration of the interplanetary magnetic field (IMF) B(sub y) into the near-Earth plasma sheet. We show that plasma sheet B(sub y) may be generated by the differential shear motion of field lines and enhanced by flux tube compression. The latter mechanism leads to a B(sub y) analogue of...
Topics: NASA Technical Reports Server (NTRS), INTERPLANETARY MAGNETIC FIELDS, MAGNETIC FLUX, PLASMA LAYERS,...
A simple model describing the process of electron collection from a low pressure ambient plasma in the absence of magnetic field and contactor velocity effects is presented. Experimental measurments of the plasma surrounding the contactor are used to demonstrate that a double-sheath generally develops and separates the ambient plasma from a higher density, anode plasma located adjacent to the contactor. Agreement between the predictions of the model and experimental measurements obtained at the...
Topics: NASA Technical Reports Server (NTRS), CONTACTORS, ELECTRODYNAMICS, HOLLOW CATHODES, PLASMAS...
As the rate of energy release in a double layer with voltage delta V is P approx I delta V, a double layer must be treated as a part of a circuit which delivers the current I. As neither double layer nor circuit can be derived from magnetofluid models of a plasma, such models are useless for treating energy transfer by means of double layers. They must be replaced by particle models and circuit theory. A simple circuit is suggested which is applied to the energizing of auroral particles, to...
Topics: NASA Technical Reports Server (NTRS), ASTROPHYSICS, ENERGY TRANSFER, PLASMA CURRENTS, PLASMA...
Electrostatic plasma double layers are numerically simulated by means of a magnetized 2 1/2 dimensional particle in cell method. The investigation of planar double layers indicates that these one dimensional potential structures are susceptible to periodic disruption by instabilities in the low potential plasmas. Only a slight increase in the double layer thickness with an increase in its obliqueness to the magnetic field is observed. Weak magnetization results in the double layer electric...
Topics: NASA Technical Reports Server (NTRS), CHARGED PARTICLES, MAGNETOHYDRODYNAMIC STABILITY, PLASMA...
A detailed treatment is presented of the dialog known as plasma surface interactions (PSI) with respect to the coating process and its tribological behavior. Adsorption, morphological changes, defect formation, sputtering, chemical etching, and secondary electron emission are all discussed as promoting and enhancing the surface chemistry, thus influencing the tribological properties of the deposited flux. Phenomenological correlations of rate of deposition, flux composition, microhardness, and...
Topics: NASA Technical Reports Server (NTRS), COATINGS, ELECTRON EMISSION, PLASMA LAYERS, PLASMAS...
Principal results are presented for the four papers that were supported from this grant. These papers include: 'Mapping and Energization in the Magnetotail. 1. Magnetospheric Boundaries; 'Mapping and Energization in the Magnetotail. 2. Particle Acceleration'; 'Cross-Tail Current: Resonant Orbits'; and 'Cross-Tail Current, Field-Aligned Current, and B(sub y)'.
Topics: NASA Technical Reports Server (NTRS), EARTH IONOSPHERE, EARTH MAGNETOSPHERE,...
It is argued that the magnetospheric source region for auroral arc breakup and substorm initiation is along boundary plasma sheet (BPS) magnetic field lines. This source region lies beyond a distinct central plasma sheet (CPS) region and sufficiently far from the Earth that energetic ion motion violates the guiding center approximation (i.e., is chaotic). The source region is not constrained to any particular range of distances from the Earth, and substorm initiation may be possible over a wide...
Topics: NASA Technical Reports Server (NTRS), AURORAL ARCS, BOUNDARY LAYERS, EARTH MAGNETOSPHERE, ELECTRIC...
Energy-principle analysis performed on two-dimensional, self-consistent solutions for magnetospheric convection indicates that the magnetosphere is unstable to isobaric (yet still frozen-in) fluctuations of plasma-sheet flux tubes. Normally, pdV work associated with compression maintains stability of the inward/outward oscillating normal mode. However, if Earth's ionosphere can provide sufficient mass flux, isobaric expansion of flux tubes can occur. The growth of a field-aligned potential drop...
Topics: NASA Technical Reports Server (NTRS), CONVECTION, EARTH IONOSPHERE, MAGNETIC FLUX, MAGNETIC STORMS,...
226
226
May 23, 2011
05/11
by
Bansal, Narottam P
texts
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Unidirectional CVD SiC(f)(SCS-6) fiber-reinforced strontium aluminosilicate (SAS) glass-ceramic matrix composites containing various volume fractions, approximately 16 to 40 volume , of fibers were fabricated by hot pressing at 1400 C for 2 h under 27.6 MPa. Monoclinic celsian, SrAl2Si2O8, was the only crystalline phase formed, with complete absence of the undesired hexacelsian phase, in the matrix. Room temperature mechanical properties were measured in 3-point flexure. The matrix...
Topics: GEOMAGNETIC TAIL, KINETIC ENERGY, PLASMA HEATING, PLASMA LAYERS, SOLAR TERRESTRIAL INTERACTIONS,...
In a triple plasma device, the injection of electron current from the source chamber to the target chamber causes the formation of a potential double layer. At a low current density, the space charge of the injected current produces a virtual cathode-type potential double layer. This double layer is stable, and various wave instabilities are observed to associate with this double layer. As the current density is increased, the double layer becomes unstable, and a moving double layer results. As...
Topics: NASA Technical Reports Server (NTRS), ELECTRIC FIELDS, ELECTRON PLASMA, MAGNETOHYDRODYNAMIC...
The properties of ion phase-space vortices are reviewed with particular attention to their role in the formation of small amplitude double layers in current-carrying plasmas. In a one-dimensional analysis, many such double layers simply add up to produce a large voltage drop. A laboratory experiment is carried out in order to investigate the properties of ion phase-space vortices in three dimensions. Their lifetime is significantly reduced as compared with similar results from one-dimensional...
Topics: NASA Technical Reports Server (NTRS), ELECTRIC FIELDS, IONS, PHASE-SPACE INTEGRAL, PLASMA LAYERS,...
The space-charge double-layer that forms between two plasmas with different densities and thermal energies was investigated using three progressively realistic models which are treated by fluid theory, and take into account four species of particles: electrons and ions reflected by the double-layer, and electrons and ions transmitted through it. The two plasmas are assumed to be cold, and the self-consistent potential, electric field and space-charge distributions within the double-layer are...
Topics: NASA Technical Reports Server (NTRS), COLD PLASMAS, FLUIDICS, PLASMA LAYERS, SPACE CHARGE, ELECTRON...
288
288
May 26, 2011
05/11
by
Stefanescu, S.; DeAnna, R. G.; Mehregany, M
texts
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Steady-state and frequency response calibration of a microfabricated heat-flux sensor have been completed. This sensor is batch fabricated using standard, micromachining techniques, allowing both miniaturization and the ability to create arrays of sensors and their corresponding interconnects. Both high-frequency and spatial response is desired, so the sensors are both thin and of small cross-sectional area. Thin-film, temperature-sensitive resistors are used as the active gauge elements. Two...
Topics: MAGNETIC STORMS, EQUATORS, FIELD ALIGNED CURRENTS, IONS, PLASMA LAYERS, TENSORS, PRESSURE...
During the past year, research has continued in improving understanding in three related areas: the mechanisms responsible for magnetospheric substorm onset, a fundamental description of field-aligned currents and parallel electric fields, and consequences of dawn-side depletion and the physics of the Harang discontinuity.
Topics: NASA Technical Reports Server (NTRS), EARTH MAGNETOSPHERE, ELECTRIC FIELDS, FIELD ALIGNED CURRENTS,...
A large set of energetic (0.1 to 16 keV/e) ion composition data from the central magnetotail, obtained by the ISEE 1 spacecraft between 10 and 23R(sub E) from Earth, is sorted according to measured total ion beta value, in order to investigate whether bulk properties of different ions vary in different ways between plasma sheets and lobes, as suggested by a comparison of certain experimental and theoretical results in the literature. Despite inevitable difficulties with extracting statistically...
Topics: NASA Technical Reports Server (NTRS), CURRENT SHEETS, GRADIENTS, INTERNATIONAL SUN EARTH EXPLORER...
The central ideas of this grant are that the magnetospheric boundary layers link disparate regions of the magnetosphere together, and the global behavior of the magnetosphere can be understood only by understanding the linking mechanisms. Accordingly the present grant includes simultaneous research on the global, meso-, and micro-scale physics of the magnetosphere and its boundary layers. These boundary layers include the bow shock, magnetosheath, the plasma sheet boundary layer, and the...
Topics: NASA Technical Reports Server (NTRS), BOUNDARY LAYERS, BOW WAVES, EARTH IONOSPHERE, EARTH...
Two different kinds of double layers were found in association with auroral precipitation. One of these is the so-called electrostatic shock, which is oriented at an oblique angle to the magnetic field in such a way that the perpendicular electric field is much larger than the parallel electric field. This type of double layer is often found at the edges of regions of upflowing ion beams and the direction of the electric fields in the shock points toward the ion beam. The potential drop through...
Topics: NASA Technical Reports Server (NTRS), AURORAS, ELECTRIC FIELDS, MAGNETOHYDRODYNAMIC STABILITY,...
Computer aided, fully-automatic TRW system sprays very hot plasma onto a turbine blade. Composed of gas into which metallic and ceramic powders have been injected, the plasma forms a two-layer coating which insulates the blade. Critical part of operation is controlling the thickness of the deposit which is measured in thousandths of an inch. This is accomplished by an optical detector which illuminates spots at various locations on the blade and determines thickness by measuring the light...
Topics: NASA Technical Reports Server (NTRS), COATING, CORROSION PREVENTION, INSOLATION, PLASMA LAYERS,...
333
333
Jul 23, 2010
07/10
by
Mcmillan, R. W
texts
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The areas of millimeter wave (MMW) research include atmospheric propagation and radiometry, advanced MMW component design with emphasis on quasi-optical techniques, and the development of MMW receivers, especially those using subharmonic mixers. Calculations of atmospheric attenuation and radiometric antenna temperature were made in the range 100 to 700 GHz, together with measurements of atmospheric antenna temperature near 95 and 183 GHz. Quasi-optical components designed include lenses,...
Topics: BOUNDARY VALUE PROBLEMS, ELECTRON ENERGY, HIGH TEMPERATURE PLASMAS, ION TEMPERATURE, PLASMA...
A plasma sprayed thermal barrier coating for diesel engines were fatigue tested. Candidate thermal barrier coating materials were fatigue screened and a data base was generated for the selected candidate material. Specimen configurations are given for the bend fatigue tests, along with test setup, specimen preparation, test matrix and procedure, and data analysis.
Topics: NASA Technical Reports Server (NTRS), BEND TESTS, FATIGUE TESTS, PLASMA LAYERS, SPRAYED COATINGS,...
Theoretical line-of-sight velocities, as would be observed by the EISCAT radar, are computed for idealized models of plasma convection in the polar ionosphere. The calculations give the velocity as a function of range and Universal Time. For several variants of the Volland and Heelis convection models, how the maxima, minima and reversals of velocity depend on beam azimuth is examined. The analysis is designed to be applied to data from the UK-POLAR experiment, an example of which is shown.
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC MODELS, CONVECTIVE FLOW, EISCAT RADAR SYSTEM...
From a limited number of observations it appears that vorticity is a common feature in the inner plasma sheet. With the four Cluster spacecraft and the four PEACE instruments positioned in a tetrahedral configuration, for the first time it is possible to directly estimate the electron fluid vorticity in a space plasma. We show examples of electron fluid vorticity from multiple plasma sheet crossings. These include three time periods when Cluster passed through a reconnection ion diffusion...
Topics: NASA Technical Reports Server (NTRS), ELECTRON PLASMA, PLASMA LAYERS, VORTICITY, MAGNETOSPHERES,...
Langmuir probe measurements were carried out which confirm the occurrence of double-layers in an argon positive column. Pulsing the discharge current permitted probe measurements to be performed in the presence of the double-layer. Supplementary evidence, obtained from DC and pulsed discharges, indicated that the double-layers formed in the two modes of operation were similar. The double-layers observed were weak and stable; their relation to other classes of double-layers are discussed, and...
Topics: NASA Technical Reports Server (NTRS), ELECTRIC DISCHARGES, ELECTROSTATIC PROBES, PLASMA JETS,...
Both external and internal phenomena impact the terrestrial magnetosphere. For example, solar wind and particle precipitation effect the distribution of hot plasma in the magnetosphere. Numerous models exist to describe different aspects of magnetosphere characteristics. For example, Tsyganenko has developed a series of models (e.g., [TSYG89]) that describe the magnetic field, and Stern [STER75] and Volland [VOLL73] have developed an analytical model that describes the convection electric...
Topics: NASA Technical Reports Server (NTRS), ELECTRIC FIELDS, GEOMAGNETISM, HIGH TEMPERATURE PLASMAS, HOT...
Geotail was launched on 24 July 1992 as the first new spacecraft of the International Solar Terrestrial Physics Program (ISTP). A primary objective of the Geotail mission is the acquisition of particles and fields measurements in the tail region of the magnetosphere. Some of the specific scientific objectives of the Geotail mission are; (1) assessment of the relative importance of solar-wind and ionospheric sources to the plasmas of the magnetotail, (2) a search for plasmoids and flux ropes,...
Topics: NASA Technical Reports Server (NTRS), SOLAR WIND, GEOMAGNETIC TAIL, SATELLITE INSTRUMENTS,...
We present Cluster observations of a series of dipolarization fronts (DF 1 to 6) at the central current sheet in Earth's magnetotail. The velocities of fast earthward flow following behind each DF 1-3, are comparable to the Alfven velocity, indicating that the flow bursts might have been generated by bursty reconnection that occurred tailward of the spacecraft. Based on multi-spacecraft timing analysis, DF normals are found to propagate mainly earthward at $160-335$ km/s with a thickness of...
Topics: NASA Technical Reports Server (NTRS), FRONTS (METEOROLOGY), MAGNETOSPHERES, PLASMA LAYERS,...
Dynamical properties of very strong double layers seen in a differentially pumped triple plasma device are reported. These double layers are V-shaped. The following findings are discussed: (1) Disruptions in the double layer potential and in the plasma current occur when an inductance is placed in series with the bias supply between the sources in the external circuit. These disruptions, which can be highly periodic, are the result of a negative resistance region. (2) When reactances in the...
Topics: NASA Technical Reports Server (NTRS), DYNAMIC CHARACTERISTICS, ELECTRIC FIELDS, MOTION STABILITY,...
Over two years of data from the Lockheed Plasma Composition Experiment on the ISEE 1 spacecraft, covering ion energies between 100 eV/e and about 16 keV/e, have been analyzed in an attempt to extract new information about three geophysical issues: (1) solar wind penetration of the Earth's magnetic tail; (2) relationship between plasma sheet and tail lobe ion composition; and (3) possible effects of heavy terrestrial ions on plasma sheet stability.
Topics: NASA Technical Reports Server (NTRS), GEOPHYSICS, INTERNATIONAL SUN EARTH EXPLORER 1, PLASMA...
Convection of plasma within the terrestrial nightside plasma sheet contributes to the structure and, possibly, the dynamical evolution of the magnetotail. In order to characterize the steady state convection process, we have extended the finite tail width model of magnetotail plasma sheet convection. The model assumes uniform plasma sources and accounts for both the duskward gradient/curvature drift and the earthward E x B drift of ions in a two-dimensional magnetic geometry. During periods of...
Topics: NASA Technical Reports Server (NTRS), CONVECTION, GEOMAGNETIC TAIL, MAGNETOHYDRODYNAMICS,...
