A5074086249- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Geomagnetism and Paleomagnetism Studies
- Astro and Planetary Science
- Earthquake Detection and Analysis
- Geophysics and Gravity Measurements
- Plasma Diagnostics and Applications
- Magnetic confinement fusion research
- Magnetic Properties and Applications
- Spacecraft Design and Technology
- Nuclear Physics and Applications
- Satellite Communication Systems
- Advanced Queuing Theory Analysis
- Electron and X-Ray Spectroscopy Techniques
- Meteorological Phenomena and Simulations
- Magnetic Field Sensors Techniques
- Calibration and Measurement Techniques
- Inertial Sensor and Navigation
- Power Line Communications and Noise
- Space Satellite Systems and Control
- Stellar, planetary, and galactic studies
- GNSS positioning and interference
- Semiconductor materials and devices
- Surface Roughness and Optical Measurements
- Atomic and Subatomic Physics Research
Goddard Space Flight Center
2015-2024
Pohang Accelerator Laboratory
2022
Pohang University of Science and Technology
2022
Heliophysics
2017-2018
University of Maryland, Baltimore County
2016
Rice University
2009
Although there is a continuous spectrum of current sheet equilibria, how particular equilibrium selected by given system remains mystery. Yet, only limited number solutions are used for analyses magnetized plasma phenomena. Here we present the exact process selection, analyzing relaxation disequilibrated under finite guide field. It shown via phase-space and particle-in-cell simulations that relaxes in such way field locally amplified, yielding mixed from spectrum. Comparisons to spacecraft...
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...
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...
Magnetic reconnection is an efficient way to convert magnetic energy into particle energy. In this paper, we use Cluster thermal electron and ion measurements in the vicinity of a X line delineate structure current sheet. Multispacecraft observations made by on 18 August 2002 indicate that drifted close spacecraft, about 3.4 R E earthward position where another had been observed earlier. Comparison Hall electric field geometry properties energetic beams streaming along separatrix between...
Plasmas are ubiquitous in nature, surround our local geospace environment, and permeate the universe. Plasma phenomena space give rise to energetic particles, aurora , solar flares coronal mass ejections, as well many interstellar space. Although plasmas can be studied laboratory settings, it is often difficult, if not impossible, replicate conditions (density, temperature, magnetic electric fields, etc.) of Single-point missions too numerous list have described properties near-Earth...
Abstract Current sheets are ubiquitous plasma structures that play the crucial role of being energy sources for various magnetic phenomena. Although a plethora current sheet equilibrium solutions have been found, collisionless process through which disequilibrated relaxes or equilibrates remains largely unknown. Here we show, analyses phase-space distributions single-particle orbit classes and particle-in-cell simulations, transitions among responsible this process. Bifurcated sheets,...
Abstract How magnetic reconnection is triggered or suppressed an important outstanding problem. By considering pinching of a current sheet that has formed at non‐equilibrium, we show the background plasma beta major controlling factor in onset and nature reconnection. A high inhibits from down to kinetic scales required for collisionless reconnection, while low facilitates it. simple adiabatic model provides good prediction reconnection‐enabled regions thickness versus peak space, which are...
Abstract Electron cyclotron harmonic (ECH) and whistler chorus waves are recognized as the two mechanisms responsible for resonant wave‐particle interactions necessary to precipitate plasma sheet electrons into ionosphere, producing diffuse Aurora. Previous work has demonstrated ECH dominate electron scattering at L shells >8, while dominates < 8. However, we find from Time History of Events Macroscale (THEMIS) Interactions during Substorms observations fast flows = 12 that oblique...
Abstract The MOST IDS team was tasked with focusing on two general areas: first to participate the Fast Plasma Investigation (FPI) in development of virtual detectors that model instrument responses MMS FPI sensors. instruments can be “flown through” both simulation data (from magnetohydrodynamic, hybrid, and kinetic simulations) Cluster THEMIS spacecraft data. goal is determine signatures magnetic reconnection expected during mission. Such serve as triggers for selection burst mode...
We present a novel technique that exploits multiple spacecraft data to determine the impact parameters of most general form magnetic reconnection at magnetopause. The method consists superposed epoch magnetometer measurements yields instantaneous spatial gradients near magnetopause site. establish positions relative analysis is well suited evaluating scales singular field line reconnection, which characterized by two‐dimensional x‐type topology adjacent and perpendicular reconnecting line....
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....
A recently published analysis of current sheets has updated the classic Harris 1D static solution by considering multiple classes charged particle trajectories in a generalized and dynamic sheet. It uses PIC simulation to describe pinching bifurcation These results strongly suggest that properties inflowing plasma, including plasma beta, have an important effect on equilibrium thickness pinched Since studies cannot magnetic reconnection, time appears right carry such over 2D or 3D...
A recently published, new analysis of current sheets updated the classic Harris 1D static solution by considering multiple classes charged particle trajectories in a generalized dynamic sheet. It used PIC simulation to describe pinching and bifurcation These results strongly suggest that plasma beta or other properties inflowing have strong effect on equilibrium thickness pinched sheet, but cannot magnetic reconnection. The time appears right carry such studies over 3D simulations where...