A5100729588- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Astro and Planetary Science
- Magnetic confinement fusion research
- Geomagnetism and Paleomagnetism Studies
- Laser-Plasma Interactions and Diagnostics
- Earthquake Detection and Analysis
- Plasma Diagnostics and Applications
- Laser-induced spectroscopy and plasma
- Organic Electronics and Photovoltaics
- Particle Accelerators and Free-Electron Lasers
- Nuclear Physics and Applications
- Atomic and Molecular Physics
- Pulsars and Gravitational Waves Research
- Geophysics and Gravity Measurements
- Particle accelerators and beam dynamics
- Radio Astronomy Observations and Technology
- Neutrino Physics Research
- Stellar, planetary, and galactic studies
- Perovskite Materials and Applications
- Functional Brain Connectivity Studies
- Advanced Neuroimaging Techniques and Applications
- Organic and Molecular Conductors Research
Los Alamos National Laboratory
2016-2025
Xijing Hospital
2014-2025
Air Force Medical University
2014-2025
New Mexico Consortium
2017-2024
Shanghai Institute of Applied Physics
2009-2024
Chinese Academy of Sciences
2008-2024
University of Chinese Academy of Sciences
2022-2024
Shanghai Advanced Research Institute
2022-2024
Wuhan University
2022-2024
Los Alamos National Security (United States)
2023
Using fully kinetic simulations, we demonstrate that magnetic reconnection in relativistic plasmas is highly efficient at accelerating particles through a first-order Fermi process resulting from the curvature drift of direction electric field induced by flows. This mechanism gives rise to formation hard power-law spectra parameter regimes where energy density reconnecting exceeds rest mass $\ensuremath{\sigma}\ensuremath{\equiv}{B}^{2}/(4\ensuremath{\pi}n{m}_{e}{c}^{2})>1$ and when system...
Magnetic reconnection is thought to be the driver for many explosive phenomena in universe. The energy release and particle acceleration during have been proposed as a mechanism producing high-energy emissions cosmic rays. We carry out two- three-dimensional (3D) kinetic simulations investigate relativistic magnetic associated acceleration. focus on electron–positron plasmas starting with magnetically dominated, force-free current sheet (). For this limit, we demonstrate that highly...
The Interstellar Mapping and Acceleration Probe (IMAP) is a revolutionary mission that simultaneously investigates two of the most important overarching issues in Heliophysics today: acceleration energetic particles interaction solar wind with local interstellar medium. While seemingly disparate, these are intimately coupled because accelerated inner heliosphere play critical roles outer heliospheric interaction. Selected by NASA 2018, IMAP planned to launch 2024. spacecraft simple...
The first self-consistent simulations of electron acceleration during magnetic reconnection in a macroscale system are presented. Consistent with solar flare observations the spectra energetic electrons take form power-laws that extend more than two decades energy. drive mechanism for these nonthermal is Fermi reflection growing and merging flux ropes. A strong guide field found to suppress production by weakening mechanism. For weak total energy content dominates hot thermal even though...
The formation of jets in black hole accretion systems is a long-standing problem. It has been proposed that jet can be formed by extracting the rotation energy (“BZ-jet”) or flow (“disk-jet”). While both models produce collimated relativistic outflows, neither successfully explained observed morphology. By using general magnetohydrodynamic simulations and considering nonthermal electrons accelerated magnetic reconnection likely driven eruption underlying flow, we obtain images radiative...
We have studied electronic excited states in films of poly(p-phenylenevinylene) using picosecond transient and cw photomodulation, photoluminescence, their excitation spectra, as well electroabsorption spectroscopy. determined all the important energy levels singlet excitons with odd even parity, onset continuum band, two-electron (biexciton) states, two relevant triplet show that good agreement exists models involving electron correlation.
Simulations suggest collisionless steady-state magnetic reconnection of Harris-type current sheets proceeds with a rate order 0.1, independent dissipation mechanism. We argue this long-standing puzzle is result constraints at the magnetohydrodynamic (MHD) scale. predict as function opening angle made by upstream fields, finding maximum close to 0.2. The predictions compare favorably particle-in-cell simulations relativistic electron-positron and nonrelativistic electron-proton reconnection....
Magnetic reconnection is a leading mechanism for dissipating magnetic energy and accelerating nonthermal particles in Poynting-flux dominated flows. In this letter, we investigate particle acceleration during magnetically-dominated ion-electron plasma using fully kinetic simulations. For an with the total magnetization $\sigma_0=B^2/(4\pi n(m_i+m_e)c^2)$, each species $\sigma_i \sim \sigma_0$ $\sigma_e (m_i/m_e) \sigma_0$, respectively. We have studied magnetically regime by varying...
Magnetic reconnection is believed to be the dominant energy release mechanism in solar flares. The standard flare model predicts both downward and upward outflow plasmas with speeds close coronal Alfvén speed. Yet, spectroscopic observations of such outflows, especially downflows, are extremely rare. With newly launched Interface Region Imaging Spectrograph (IRIS), we report detection a greatly redshifted (∼125 km s−1 along line sight) Fe xxi 1354.08 Å emission ∼100 nonthermal width at site...
Abstract Magnetic reconnection is a primary mechanism for particle energization in space and astrophysical plasmas. By carrying out two-dimensional (2D) fully kinetic simulations, we study acceleration during magnetic plasmas with different plasma β (the ratio between the thermal pressure pressure). For high- cases, do not observe significant acceleration. In low- regime ( <?CDATA $\beta \lt 0.1$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>β</mml:mi>...
The relaxation of field-line tension during magnetic reconnection gives rise to a universal Fermi acceleration process involving the curvature drift particles. However, efficiency this mechanism is limited by trapping energetic particles within flux ropes. Using 3D fully kinetic simulations, we demonstrate that flux-rope kink instability leads strong chaos in weak-guide-field regimes where most efficient, thus allowing transport out ropes and undergo further acceleration. As consequence,...
Magnetic reconnection in the relativistic regime has been proposed as an important process for efficient production of nonthermal particles and high-energy emissions. Using fully kinetic particle-in-cell simulations, we investigate how guide-field strength domain size affect characteristic spectral features acceleration processes. We study two stages acceleration: energization up until injection energy $\gamma_{\rm inj}$ further that generates a power-law spectrum. Stronger guide fields...
Abstract Magnetic reconnection occurs ubiquitously in the universe and is often invoked to explain fast energy release particle acceleration high-energy astrophysics. The study of relativistic magnetic magnetically dominated regime has surged over past two decades, revealing physics nonthermal acceleration. Here we review these recent progresses, including magnetohydrodynamic collisionless dynamics as well energization. insights astrophysical strongly connect development other areas, further...
Computationally challenging 3D hybrid simulations of magnetic reconnection for multiple ion species give insights into the acceleration process heavy ions and energy spectra compatible with in-situ spacecraft observations.
Abstract Relativistic magnetic turbulence has been proposed as a process for producing nonthermal particles in high-energy astrophysics. The particle energization may be contributed by both reconnection and turbulent fluctuations, but their interplay is poorly understood. It suggested that during the parallel electric field dominates acceleration up to lower bound of power-law spectrum, recent studies show fields perpendicular can play an important, if not dominant role. In this study, we...
A plausible representation of relational information among entities in dynamic systems such as a living cell or social community is stochastic network which topologically rewiring and semantically evolving over time. While there rich literature on modeling static temporally invariant networks, much less has been done toward the processes underlying recovering networks when they are not observable. We present class hidden temporal exponential random graph models (htERGMs) to study yet...
By means of fully kinetic simulations, we investigate electron acceleration during magnetic reconnection in a nonrelativistic proton--electron plasma with conditions similar to solar corona and flares. We demonstrate that leads nonthermally dominated power-law energy distribution the low-$\beta$ regime but not high-$\beta$ regime, where $\beta$ is ratio thermal pressure pressure. The accelerated electrons contain most dissipated regime. A guiding-center current description used reveal role...
The polarization signatures of the blazar emissions are known to be highly variable. In addition small fluctuations angle around a mean value, sometimes large (> 180^o) swings observed. We suggest that such p henomena can interpreted as arising from light-travel-time effects within an underlying axisymmetric emission region. present first simultaneous fitting multi-wavelength spectrum, variability and time-dependent features correlated optical gamma-ray flaring event prominent 3C279,...
Using fully kinetic simulations, we study the scaling of inflow speed collisionless magnetic reconnection in electron-positron plasmas from nonrelativistic to ultrarelativistic limit. In antiparallel configuration, increases with upstream magnetization parameter $\ensuremath{\sigma}$ and approaches light when $\ensuremath{\sigma}>O(100)$, leading an enhanced rate. all regimes, divergence pressure tensor is dominant term responsible for breaking frozen-in condition at $x$ line. The observed...
Abstract While observations have suggested that power-law electron energy spectra are a common outcome of strong release during magnetic reconnection, e.g., in solar flares, kinetic simulations not been able to provide definite evidence power-laws nonrelativistic reconnection. By means 3D large-scale fully simulations, we study the formation low- β We find both global spectrum integrated over entire domain and local within individual regions reconnection layer tails with spectral index p ∼ 4...
Particle acceleration in space and astrophysical reconnection sites is an important unsolved problem studies of magnetic reconnection. Earlier kinetic simulations have identified several mechanisms that are associated with particle drift motions. Here, we show that, for sufficient large systems, the energization processes due to motions can be described as fluid compression shear, shear proportional pressure anisotropy energetic particles. By analyzing results from fully simulations,...