Publications (35)
The Persistent Mystery of Collisionless Shocks
Katherine Goodrich, Steven Schwartz, Lynn Wilson +14
Collisionless shock waves are one of the main forms of energy conversion in space plasmas. They can directly or indirectly drive other universal plasma processes such as magnetic r…
A new Look at the Electron Diffusion Region in Asymmetric Magnetic Reconnection
Michael Hesse, Cecilia Norgren, Paul Tenfjord +10
A new look at the structure of the electron diffusion region in collisionless magnetic reconnection is presented. The research is based on a particle-in-cell simulation of asymmetr…
Enhanced Electron Mixing and Heating in 3D Asymmetric Reconnection at the Earth's Magnetopause
Ari Le, William Daughton, Li-Jen Chen +1
Electron heating and mixing during asymmetric reconnection are studied with a 3D kinetic simulation that matches plasma parameters from Magnetospheric Multiscale (MMS) spacecraft o…
Observational evidence of magnetic reconnection in the terrestrial bow shock transition region
Shan Wang, Li-Jen Chen, Naoki Bessho +7
We report evidence of magnetic reconnection in the transition region of the terrestrial bow shock when the angle between the shock normal and the immediate upstream magnetic field…
2.5-D Decomposition for LLM-Based Spatial Construction
Paul Whitten, Li-Jen Chen, Sharath Baddam
Autonomous systems that build structures from natural-language instructions need reliable spatial reasoning, yet large language models (LLMs) make systematic coordinate errors when…
Electron energy partition across interplanetary shocks: I. Methodology and Data Product
Lynn B. Wilson, Li-Jen Chen, Shan Wang +10
Analysis of 15314 electron velocity distribution functions (VDFs) within 2 hours of 52 interplanetary (IP) shocks observed by the \emph{Wind} spacecraft near 1 AU are introduc…
The evolution of CME sheath turbulence from L1 to Earth: Wind and MMS observations of the 2023-04-23 CME
Matthew R. Argall, Li-Jen Chen, Noé Lugaz +5
An interplanetary shock driven by a coronal mass ejection (CME) containing an interval of sub-Alfvénic flow impacted Earth on April 23, 2024. In this article, we analyze the turbu…
Width-amplitude relation of Bernstein-Greene-Kruskal solitary waves
Li-Jen Chen, David J. Thouless, Jian-Ming Tang
Inequality width-amplitude relations for three-dimensional Bernstein-Greene-Kruskal solitary waves are derived for magnetized plasmas. Criteria for neglecting effects of nonzero cy…
Magnitude of Short-Wavelength Electric Field Fluctuations in Simulations of Collisionless Plasma Shocks
Vadim Roytershteyn, Lynn B. Wilson, Li-Jen Chen +2
Large-amplitude electrostatic fluctuations are routinely observed by spacecraft upon traversal of collisionless shocks in the heliosphere. Kinetic simulations of shocks have strugg…
BGK Electron Solitary Waves Reexamined
Li-Jen Chen, George K. Parks
This paper reexamines the physical roles of trapped and passing electrons in electron Bernstein-Greene-Kruskal (BGK) solitary waves, also called the BGK phase space electron holes…
Direct Evidence for Magnetic Reflection of Heavy Ions from High Mach Number Collisionless Shocks
Hadi Madanian, Steven J. Schwartz, Stephen A. Fuselier +5
Strong shocks in collisionless plasmas, such as supernovae shocks and shocks driven by coronal mass ejections, are known to be a primary source of energetic particles. Due to their…
Ion-scale current structures in Short Large-Amplitude Magnetic Structures
Shan Wang, Li-Jen Chen, Naoki Bessho +7
We investigate electric current structures in Short Large-Amplitude Magnetic Structures (SLAMS) in the terrestrial ion foreshock region observed by the Magnetospheric Multiscale mi…
Field Aligned Currents and Auroral Precipitation During the Terrestrial Alfven Wing State
Brandon Burkholder, Li-Jen Chen, Kareem Sorathia +3
When sub-Alfvénic (Alfvén Mach number MA < 1) plasmas impact Earth, Alfvén wings (AWs) develop. A Multiscale Atmosphere Geospace Environment (MAGE) simulation of the April 2023…
Interplanetary magnetic field controlled Alfvén wings at Earth during encounter of a coronal mass ejection
Yuxi Chen, Chuanfei Dong, Li-Jen Chen +2
In the vicinity of Earth's orbit, the typical solar wind Alfvén Mach number exceeds 5, and the super-Alfvénic solar wind drives a conventional magnetosphere configuration. Howeve…
Observation of O+ Characteristics During the Terrestrial Alfvén Wing State Induced by the April 2023 Coronal Mass Ejection
Haoming Liang, Li-Jen Chen, Stephen A. Fuselier +7
We report Magnetospheric Multiscale observations of oxygen ions (O+) during a coronal mass ejection in April 2023 when the solar wind was sub-Alfvénic and Alfvén wings formed. Fo…
System Size Dependence of Collisionless Reconnection Rate
Yi-Min Huang, Naoki Bessho, Li-Jen Chen +2
It is a widely accepted paradigm that collisionless magnetic reconnection proceeds at a universal fast rate of when normalized to a properly defined reconnecting magnetic…
Electron energy partition across interplanetary shocks: II. Statistics
Lynn B. Wilson, Li-Jen Chen, Shan Wang +10
A statistical analysis of 15,210 electron velocity distribution function (VDF) fits, observed within 2 hours of 52 interplanetary (IP) shocks by the spacecraft near 1 A…
Drift Turbulence, Particle Transport, and Anomalous Dissipation at the Reconnecting Magnetopause
Ari Le, William Daughton, Obioma Ohia +5
Using fully kinetic 3D simulations, the reconnection dynamics of asymmetric current sheets are examined at the Earth's magnetopause. The plasma parameters are selected to model MMS…
Drivers of Magnetic Field Amplification at Oblique Shocks: In-Situ Observations
Hadi Madanian, Imogen Gingell, Li-Jen Chen +1
Collisionless shocks are ubiquitous structures throughout the universe. Shock waves in space and astrophysical plasmas convert the energy of a fast-flowing plasma to other forms of…
Earth's Alfvén wings driven by the April 2023 Coronal Mass Ejection
Li-Jen Chen, Daniel Gershman, Brandon Burkholder +33
We report a rare regime of Earth's magnetosphere interaction with sub-Alfvénic solar wind in which the windsock-like magnetosphere transforms into one with Alfvén wings. In the m…
Turbulence properties and kinetic signatures of electron in Kelvin-Helmholtz waves during a geomagnetic storm
Harsha Gurram, Jason R. Shuster, Li-Jen Chen +5
We present a comprehensive study of Magnetospheric Multiscale (MMS) spacecraft encounter with KHI during a geomagnetic storm, focusing on elucidating key turbulence properties and…
Statistical study of energy dissipation in magnetic structures during turbulent reconnection in the Earth's magnetotail
Rachel Wang, Hantao Ji, Adam Robbins +7
Magnetic reconnection is a ubiquitous plasma phenomenon that plays a critical role in particle heating and energization. During reconnection, the topology of magnetic field rearran…
Interaction of the Prominence Plasma within the Magnetic Cloud of an ICME with the Earth's Bow Shock
Hadi Madanian, Li-Jen Chen, Jonathan Ng +5
The magnetic cloud within an interplanetary coronal mass ejection (ICME) is characterized by high magnetic field intensities. In this study, we investigate the interaction of a mag…
Challenges and the next transformative steps in understanding plasma turbulence from the perspective of multi-spacecraft measurements
Li-Jen Chen, Naoki Bessho, Jay A. Bookbinder +18
We have become heavily reliant on electrical technologies, from power grids to GPS to wireless communication. Any disruption of these systems will have severe global consequences.…
Laboratory measurements of electrostatic solitary structures generated by electron beam injection
Bertrand Lefebvre, Li-Jen Chen, Walter Gekelman +6
Electrostatic solitary structures are generated by injection of a suprathermal electron beam parallel to the magnetic field in a laboratory plasma. Electric microprobes with tips s…
Magnetopause reconnection and indents induced by foreshock turbulence
Li-Jen Chen, Jonathan Ng, Yuri Omelchenko +1
Based on global hybrid simulation results, we predict that foreshock turbulence can reach the magnetopause and lead to reconnection as well as Earth-sized indents. Both the interpl…
MMS Insights into CME Driven Sub-Alfvénic Solar Wind at 1 AU
Harsha Gurram, Li-Jen Chen, Matthew R. Argall +4
We report the properties of electron distributions and turbulence during a Coronal Mass Ejection (CME) in April 2023 observed by Magnetospheric Multiscale (MMS). The CME exhibits a…
Field-Aligned Current Structures during the Terrestrial Magnetosphere's Transformation into Alfven Wings and Recovery
Jason M. H. Beedle, Li-Jen Chen, Jason R. Shuster +8
On April 24th, 2023, a CME event caused the solar wind to become sub-Alfvenic, leading to the development of an Alfven Wing configuration in the Earth's Magnetosphere. Alfven Wings…
Earth's Alfvén Wings: Unveiling Dynamic Variations of Field-line Topologies with Electron Distributions
Harsha Gurram, Jason R. Shuster, Li-Jen Chen +6
The magnetic cloud (MC) of the Coronal Mass Ejection on April 24, 2023, contains sub-Alfvénic solar wind, transforming Earth's magnetosphere from conventional bow-shock magnetotai…
Foreshock Ultra-Low Frequency Waves at Mars: Consequence on the Particle Acceleration Mechanisms at the Martian Bow Shock
Nahuel Andrés, Norberto Romanelli, Christian Mazelle +3
Using Mars Atmosphere and Volatile EvolutioN Magnetometer observations, we report the first statistical study of ultra-low frequency (ULF) waves at the Martian foreshock. The analy…
Intermittent Electron-Only Reconnection at Lunar Mini-Magnetospheres
Adam Stanier, Li-Jen Chen, Ari Le +2
Lunar crustal magnetic anomalies (LCMA) are sub-ion-gyroradius structures that have been shown to stand off the solar wind (SW) plasma from the Moon's surface, forming shock-like d…
HelioSwarm: A Multipoint, Multiscale Mission to Characterize Turbulence
Kristopher G. Klein, Harlan Spence, Olga Alexandrova +47
HelioSwarm (HS) is a NASA Medium-Class Explorer mission of the Heliophysics Division designed to explore the dynamic three-dimensional mechanisms controlling the physics of plasma…
Simulation Models for Exploring Magnetic Reconnection
Michael Shay, Subash Adhikari, Naoki Beesho +22
Simulations have played a critical role in the advancement of our knowledge of magnetic reconnection. However, due to the inherently multiscale nature of reconnection, it is imposs…
Electron energy partition across interplanetary shocks: III. Analysis
L. B. Wilson, Li-Jen Chen, Shan Wang +10
Analysis of model fit results of 15,210 electron velocity distribution functions (VDFs), observed within 2 hours of 52 interplanetary (IP) shocks by the Wind spacecraft near 1…
Impact of the Out-of-Plane Flow Shear on Magnetic Reconnection at the Flanks of Earth's Magnetopause
Haoming Liang, Li-Jen Chen, Naoki Bessho +1
Magnetic reconnection changes the magnetic field topology and facilitates the energy and particle exchange at magnetospheric boundaries such as the Earth's magnetopause. The flow s…