A5012261924- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Astro and Planetary Science
- Earthquake Detection and Analysis
- Magnetic confinement fusion research
- Planetary Science and Exploration
- Atmospheric Ozone and Climate
- Dust and Plasma Wave Phenomena
- Laser-induced spectroscopy and plasma
- Plasma Diagnostics and Applications
- Spacecraft Design and Technology
- Nuclear Physics and Applications
- Geophysics and Gravity Measurements
- Atomic and Subatomic Physics Research
- Magnetic Field Sensors Techniques
- Space exploration and regulation
- Electron and X-Ray Spectroscopy Techniques
- Photocathodes and Microchannel Plates
- Space Exploration and Technology
- Market Dynamics and Volatility
- Lightning and Electromagnetic Phenomena
- X-ray Spectroscopy and Fluorescence Analysis
- Spacecraft and Cryogenic Technologies
- Advanced Data Compression Techniques
Goddard Space Flight Center
2011-2023
Auburn University
2023
DigitalSpace (United States)
2023
University of Maryland, Baltimore County
2016
Heliophysics
2012-2014
Heliophysics Science Division
2012
University of Alabama in Huntsville
1996-2011
Marshall Space Flight Center
2000-2005
National Space Science and Technology Center
2002
The Fast Plasma Investigation (FPI) was developed for flight on the Magnetospheric Multiscale (MMS) mission to measure differential directional flux of magnetospheric electrons and ions with unprecedented time resolution resolve kinetic-scale plasma dynamics. This increased has been accomplished by placing four dual 180-degree top hat spectrometers around periphery each MMS spacecraft. Using electrostatic field-of-view deflection, eight species together provide 4pi-sr with, at worst,...
The Cluster spacecraft were favorably positioned on the nightside near equatorial plasmapause of Earth at L ∼ 4.3 30 March 2002 to observe electromagnetic ion cyclotron (EMIC) rising tone emissions in association with Pc1 waves 1.5 Hz. EMIC found be left‐hand, circularly polarized, dispersive, and propagating away from equator. Their burstiness dispersion ∼30s/Hz out Hz are consistent their identification as triggered chorus emissions, first reported through situ observations plasmapause....
Deep plasmaspheric notches can extend over more than 2 R E in radial distance and 3 hours MLT the magnetic equatorial plane, as observed by extreme ultraviolet (EUV) imager on IMAGE mission. They are among largest evacuated features exterior boundary. last for days exhibit a variety of shapes. It appears that weak convection limited erosion precedes notch formation at westward, near‐Earth edge plume. Eighteen clear events were found analyzed 2000. Among these events, to drift slowly 44%...
We report our findings comparing the geometric factor (\documentclass[12pt]{minimal}\begin{document}$\mathbb {GF}$\end{document}GF) as determined from simulations and laboratory measurements of new Dual Electron Spectrometer (DES) being developed at NASA Goddard Space Flight Center part Fast Plasma Investigation on NASA’s Magnetospheric Multiscale mission. Particle are increasingly playing an essential role in design calibration electrostatic analyzers, facilitating identification mitigation...
The Poincaré index indicates that the Cluster spacecraft tetrahedron entraps a number of 3‐D magnetic nulls during an encounter with turbulent magnetosheath. Previous researchers have found evidence for reconnection at one many filamentary current layers observed by in this region. We find entrained are also associated strong currents. dissect structure pair spiral may be topologically connected. At both nulls, we along spine, accompanied somewhat more modest perpendicular to spine tilts fan...
Abstract Global observations of He + ions from the Imager for Magnetopause‐to‐Aurora Exploration mission Extreme Ultraviolet are used to examine dynamics plasmasphere content using integrated mass through times erosion and refilling . Perhaps most basic important attributes its spatial distribution. However, our understanding is often constrained by method measurement. Storm‐time loss a kind exhalation where plasma lost. Refilling or inhalation into body occurs during following calm. Using...
We investigate the distribution of parallel electric fields and their relationship to location rate magnetic reconnection in a large particle-in-cell simulation 3D turbulent with open boundary conditions. The simulation's guide field geometry inhibits formation simple topological features such as null points. Therefore, we derive potential changes connectivity by finding lines that experience relative change between endpoints, i.e., quasi-separatrix layer. find good correspondence locus or...
ABSTRACT The solar wind electron velocity distribution function (eVDF) exhibits a variety of non-thermal features that deviate from thermal equilibrium. These deviations equilibrium provide local source for electromagnetic fluctuation emissions, including the commonly observed whistler-cyclotron and firehose instabilities. We present systematic analysis Wind -SWE-VEIS observations plasma associated -MFI magnetic fluctuations. For first time using full its moments, without separation various...
We present EUV observations of the plasmasphere from 1938 to 2211 UT on 28 June 2000 characterized by presence bifurcated radial enhancements He + plasma distribution in nightside sector. These features remain stable throughout period observation and are found move about Earth at 67% corotation rate. Two‐dimensional simulation assuming an azimuthal standing wave patterns L = 1.8 2.5 suggests that organization outer is result convective motion driven a ULF wave. Preliminary analysis...
Measurements of electromagnetic radiation pressure have been made on individual silica (SiO 2 ) particles levitated in an electrodynamic balance. These measurements were by inserting single charged known diameter the 0.2‐ to 6.82‐μm range and irradiating them from above with laser focused beam widths ∼175–400 μm at ambient pressures ∼10 −3 –10 −4 torr. The downward displacement particle due force is balanced electrostatic indicated compensating dc potential applied balance electrodes,...
The electron‐velocity‐distribution function was determined to be highly non‐Maxwellian and more appropriate a kappa distribution, with κ ≈ 2.0, near magnetic midnight in the low‐latitude magnetosphere just outside stable plasmasphere during extremely quiet geomagnetic conditions. results were based on sounder‐stimulated Qn plasma resonances using Radio Plasma Imager (RPI) IMAGE satellite; state of from IMAGE/EUV observations. correspond maximum frequencies Bernstein‐mode waves that are...
Low energy (0.3–25 eV) ion plasma composition and three‐dimensional differential velocity distribution measurements have been made from the Sounding of Cleft Ion Fountain Energization Region (SCIFER) mission. SCIFER traveled poleward into dayside prenoon cleft region under conditions low solar activity. Upleg show that subcleft topside had a rapid density fall‐off with altitude (n e ≤ 300 cm −3 at 1400 km altitude), payload floating potential changed typical ionospheric negative values about...
Differential directional ionospheric electron measurements at energies from <1 to 60 eV have been obtained in the Earth's geomagnetic cleft ionosphere on NASA's Sounding of Cleft Region Ion Fountain Energization (SCIFER) rocket. We introduce data set, present temperature measurements, and show examples phase space distributions measured near ionosphere. Topside temperatures ranged 0.15 south high energy trapping boundary 1 within precipitation regions auroral cleft. Field‐aligned bursts...
We apply a scalar measure of nongyrotropy to the electron pressure tensor in 2D particle-in-cell simulation guide field reconnection and assess corresponding distributions forces that account for nongyrotropy. The reveals lies bands straddle diffusion region separatrices, same regions where there are parallel electric fields. Analysis fields shows along inflow outflow separatrices emerges as result multiple populations electrons influenced differently by large small-scale gradients field....
Abstract Direct measurement of low < 1 eV electron temperature is difficult to make in the Earth's inner magnetosphere for densities ( N e ) 3 × 10 2 cm −3 . We compute these quantities by solving current balance equations low‐density regions. Concurrent measurements from Polar spacecraft relative potential V S − P ), between body and electric field probe, density derived upper hybrid frequency f UHR were used solve T s , p Where probe nearby plasma. The assumption that bulk plasma...
Abstract Whistlers observed outside the plasmasphere by Cluster have been correlated with global using Imager for Magnetopause‐to‐Aurora Global Exploration‐Extreme Ultraviolet (IMAGE‐EUV) observations. Of 12 Cluster‐observed whistler events reported, EUV is able to provide imaging of every event and demonstrates a direct correlation between detection lightning‐generated whistlers beyond plasmapause presence perturbation local plasmapause. these events, seven (or 58%) are associated...
Abstract The four Magnetospheric Multiscale (MMS) spacecraft observed energetic ( keV) ion bursts exhibiting an inverse dispersion in the magnetosheath on 28 December 2015. We consider possibility that these ions originate from magnetosphere. composition ratios, flux levels, and spectral slopes of energy spectra foreshock resemble those outer magnetosphere but differ significantly seen further upstream bow shock at ACE. particle gyrocenters lie earthward spacecraft, indicating maximum fluxes...
Solar sails presently have mass loadings of 5 gm/m2 that, when including the support structure and payload, could easily average to >10 gm/m2. For reasonably sized spacecraft, critical parameter is total per area, which combined with reflectivity, yield true acceleration. We propose that dusty plasmas trapped in a “Mini-Magnetosphere” (Winglee, 2000) can produce solar sail loading <0.01 gm/m2, reflectivities ∼1%. This configuration provides an acceleration equivalent standard 95%...
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