A5081918433- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Fusion materials and technologies
- Nuclear Materials and Properties
- Earthquake Detection and Analysis
- ZnO doping and properties
- Graphene research and applications
- Metal and Thin Film Mechanics
- Geomagnetism and Paleomagnetism Studies
- Ion-surface interactions and analysis
- Hydrogen embrittlement and corrosion behaviors in metals
- Semiconductor materials and devices
- Diamond and Carbon-based Materials Research
- GNSS positioning and interference
- Graphite, nuclear technology, radiation studies
- Astro and Planetary Science
- Carbon Nanotubes in Composites
- Plasma Diagnostics and Applications
- Advanced Memory and Neural Computing
- Nuclear reactor physics and engineering
- Advanced Condensed Matter Physics
- Silicon and Solar Cell Technologies
- Solid-state spectroscopy and crystallography
- Radiation Detection and Scintillator Technologies
- Thin-Film Transistor Technologies
Los Alamos National Laboratory
2022-2024
New Jersey Institute of Technology
2020-2024
Los Alamos National Security (United States)
2023
Virginia Tech
2023
Dankook University
2010-2020
Chungbuk National University
2013-2018
Inje University
2013-2018
Dongnam Institute of Radiological & Medical Sciences
2018
Korea Astronomy and Space Science Institute
2016
Seoul National University
2011
Abstract Interplanetary magnetic flux ropes (MFRs) are commonly observed structures in the solar wind, categorized as clouds (MCs) and small-scale MFRs (SMFRs) depending on whether they associated with coronal mass ejections. We apply machine learning to systematically compare SMFRs, MCs, ambient wind plasma properties. construct a data set of 3-minute averaged sequential points wind’s instantaneous bulk fluid properties using about 20 years measurements from Wind. label samples by presence...
Abstract Small-scale interplanetary magnetic flux ropes (SMFRs) are similar to ICMEs in structure, but smaller and do not exhibit coronal mass ejection plasma signatures. We present a computationally efficient GPU-powered version of the single-spacecraft automated SMFR detection algorithm based on Grad–Shafranov (GS) technique. Our can process higher resolution data, eliminates selection bias caused by fixed 〈 B 〉 threshold, has improved criteria demonstrated have better results an MHD...
Abstract This paper presents a comprehensive exploration of the Interstellar Boundary Explorer energetic neutral atom (ENA) ribbon, focusing on its spatial and temporal variations over 14 yr. Methodological advancements, including refined map modeling procedure new ribbon separation technique with appropriate error propagation, enable detailed investigation ribbon’s features. Utilizing statistically robust metrics, this study reveals details across energy time. Key findings include energy-...
Abstract Rapid injection of MeV electrons associated with strong substorm dipolarization has been suggested as a potential explanation for some radiation belt enhancement events. However, it difficult to quantify the contribution electron injections enhancements. This paper presents two isolated events which we quite precisely how entire outer‐belt immediately changed injections. Tracking detailed evolution observed by Van Allen Probes, both events, identify large step‐like relativistic...
It has become well-established that strong outer radiation belt enhancements are due to wave-driven electron energization by whistler-mode chorus waves. However, in this study, we examine MeV injections on 10 July 2019 and find substantial evidence such may be a crucial contributor enhancement events. For an examination, it is essential precisely separate temporal flux changes from spatial variations observed as Van Allen Probes move along their orbits. Employing new “hourly snapshot”...
Water dispersible ZnS:Mn nanocrystals were synthesized by capping the surface of with four kinds aminoacids ligands: arginine, cystein, histidine, and methionine. The capped nanocrystal powders characterized XRD, HR-TEM, EDXS, FT-IR spectroscopy. optical properties colloidal also measured UV/Vis solution photoluminescence (PL) spectroscopies in aqueous solvents. PL spectra showed broad emission peaks around 575 nm (orange light emissions) efficiencies range 4.4 to 7.1%. particle sizes for...
Abstract We present the results of a multi‐point and multi‐instrument study electromagnetic ion cyclotron (EMIC) waves related energetic proton precipitation during substorm. analyze data from Arase (ERG) Van Allen Probes (VAPs) A B spacecraft for an event 16 17 UT on December 1, 2018. VAP‐A detected almost dispersionless injection protons to substorm onset in night sector. Then was by VAP‐B further Arase, as dispersive enhancement flux. The flux at every coincided with EMIC wave or...
Abstract We report on observations of electromagnetic ion cyclotron (EMIC) waves and their interactions with injected ring current particles high energy radiation belt electrons. The magnetic field experiment aboard the twin Van Allen Probes spacecraft measured EMIC near L = 5.5–6. Particle data from show that were associated particle injections. wave activity was also observed by a ground‐based magnetometer geomagnetic footprint over more extensive temporal range. Phase space density...
Abstract Observation of growing phase space density (PSD) peak in the outer electron radiation belt has been considered evidence for local wave‐driven acceleration as a primary cause enhancement. However, recent studies showed that strong substorm‐associated MeV injections can also significant enhancements on fast timescales (∼10s min). Such rapid pose challenges determining true spatial PSD profiles. To address this, we conduct detailed spatiotemporal analysis flux and during an enhancement...
Abstract In this study, we report on small-scale magnetic flux ropes (SMFRs) observed as a compact series in narrow Carrington longitudinal range during three Parker Solar Probe (PSP) encounters. First, ∼1.5 days of PSP's inbound part Encounter 4, identified 11 SMFRs within 1.°4 longitude over the radial distance ∼8.4 R ☉ (from ∼44 to 35 ). The lasted from ∼0.5 1.8 hr, and adjacent events were separated mostly by few hours up ∼6.5 hr at longest, but some very closely spaced with intervals...
Abstract Physics of electromagnetic ion cyclotron (EMIC) waves is complicated by inclusion heavy ions. In particular, He + ions in the magnetosphere have long been considered to play important roles. Motivated recent observations, we examine effect hot anisotropic addition usual protons. We solve kinetic dispersion relation for this examination and find following results. First, leads growth EMIC at frequencies below gyrofrequency (He band) a reduction wave rates (or damping waves) between...
Abstract Anisotropic velocity distributions of protons have long been considered as free energy sources for exciting electromagnetic ion cyclotron (EMIC) waves in the Earth's magnetosphere. Here we rigorously calculated proton anisotropy parameter using data obtained from Van Allen Probe‐A observations. The calculations are performed times during EMIC wave events (distinguishing immediately after and before onsets) exhibiting no waves. We find that values often larger onsets than just...
Abstract Magnetospheric compression due to impact of enhanced solar wind dynamic pressure P dyn has long been considered as one the generation mechanisms electromagnetic ion cyclotron (EMIC) waves. With Van Allen Probe‐A observations, we identify three EMIC wave events that are triggered by enhancements under prolonged northward interplanetary magnetic field (IMF) quiet time preconditions. They in contrast another a few aspects. Event 1 occurs middle continuously increasing while is located...
Low temperature photoluminescence (PL) measurements were carried out to investigate optical transition characteristics of ZnO nanowires, Ni nanodot, and NiO coated nanowires (NWs). PL emission spectra show peaks distinctive bound exciton neutral donor (DX0) acceptor (AX0) transition. The authors found that the quenching was drastic with increasing activation energies are unusually small. major peak for NW switched from DX0 AX0 Ni–ZnO nanodot NWs. This is due reason diffused hydrogen atoms...
Abstract In this paper, using the multisatellite (the Van Allen Probes and two GOES satellites) observations in inner magnetosphere, we examine electromagnetic ion cyclotron (EMIC) wave events that are triggered by P dyn enhancements under prolonged northward interplanetary magnetic field quiet time preconditions. For both events, impact of enhanced causes EMIC waves at multiple points. However, find a strong spatial dependence due to can occur points (likely globally but not necessarily...
The correlation between the sintering temperature and dielectric properties in <TEX>$Nb^{5+}\;and\;Ta^{5+}$</TEX> doped BaTi<TEX>$O_3$</TEX> solid solutions have been investigated. samples were sintered at temperatures ranging from 1250 to 1350 <TEX>${^{\circ}C}$</TEX> for 4 h air. SEM, XRD SEM/EDS techniques used examine structure of with particular focus on incorporation ions into crystal lattice. X-ray diffraction peaks (111), (200) (002) planes solution different fractions analyzed...
Abstract In the present study, we explore observational characteristics of Electromagnetic Ion Cyclotron (EMIC) wave propagation from source region to ground. We use magnetometers aboard Geostationary Operational Environment Satellite (GOES) 13, geosynchronous orbit satellite at 75°W, and Sanikiluaq ground station (SNK, 79.14°W 56.32°N in geographic coordinates, L ∼ 6.0 a dipole magnetic field) which is located northern Canada. Using these magnetically conjugate observatories, simultaneous...
The Korean heliospheric community, led by the Korea Astronomy and Space Science Institute (KASI), is currently assessing viability of deploying a spacecraft at Sun-Earth Lagrange Point L4 in collaboration with National Aeronautics Administration (NASA). aim this mission to utilize combination remote sensing situ instruments for comprehensive observations, complementing capabilities L1 L5 observatories. paper outlines long-term scientific objectives, underscoring significance multi-point...