A5053175210- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Astro and Planetary Science
- Earthquake Detection and Analysis
- Atomic and Molecular Physics
- Mechanical and Optical Resonators
- Gyrotron and Vacuum Electronics Research
- Particle Accelerators and Free-Electron Lasers
- Laser-induced spectroscopy and plasma
- Acoustic Wave Resonator Technologies
- Radiation Effects and Dosimetry
- Semiconductor materials and interfaces
- Semiconductor materials and devices
- Astrophysics and Star Formation Studies
- Innovative Teaching Methods
- Pulsed Power Technology Applications
- Ocean Waves and Remote Sensing
- Underwater Vehicles and Communication Systems
- Nonlinear Photonic Systems
- Geophysics and Sensor Technology
- Advancements in Battery Materials
- Astrophysics and Cosmic Phenomena
Los Alamos National Laboratory
2021-2025
University of Wisconsin–Madison
2016-2022
Massachusetts Institute of Technology
2017
Purdue University West Lafayette
2016
Institute of Nanotechnology
2016
Supported by a kinetic simulation, we derive an exclusion energy parameter ${\mathcal{E}}_{X}$ providing lower bound for electron to cross from one inflow region the other during magnetic reconnection. As Maxwell demon, only high-energy electrons are permitted inner reconnection region, setting distribution function observed along low-density side separatrix asymmetric The analytic model accounts two distinct flavors of crescent-shaped distributions spacecraft in thin boundary layer separatrix.
Aided by fully kinetic simulations, spacecraft observations of magnetic reconnection in Earth's magnetotail are analyzed. The structure the electron diffusion region is quantitative agreement with numerical model. Of special interest, data reveal how mediated off-diagonal stress pressure tensor breaking frozen-in law fluid.
Hybrid-VPIC is an extension of the open-source high-performance particle-in-cell (PIC) code VPIC incorporating hybrid kinetic ion/fluid electron solvers. This paper describes models that are available in and gives overview applications to space laboratory plasma physics problems. Particular choices how solvers were implemented documented for reference by users. A few solutions handling numerical complications particular codes also described. Special emphasis given computationally taxing...
The kinetic stability of collisionless, sloshing beam-ion (\(45^{\circ}\) pitch angle) plasma is studied in a 3D simple magnetic mirror, mimicking the Wisconsin High-temperature superconductor Axisymmetric Mirror (WHAM) experiment. collisional Fokker-Planck code CQL3D-m provides slowing-down distribution to initialize kinetic-ion/fluid-electron Hybrid-VPIC, which then simulates free decay without external heating or fueling. Over \(1\)–\(10\;\mathrm{\mu s}\), drift-cyclotron loss-cone (DCLC)...
Previous work has shown that Fermi acceleration can be an effective heating mechanism during magnetic island coalescence, where electrons may undergo repeated reflections as the field lines contract. This energization potential to account for power-law distributions of particle energy inferred from observations solar flares. Here, we develop a generalized framework analysis incorporate effects compressibility and non-uniformity along lines, which have commonly been neglected in previous...
Fully kinetic simulations of asymmetric magnetic reconnection reveal the presence magnetic-field-aligned beams electrons flowing toward topological x line. Within ∼6d_{e} electron-diffusion region, become oblique to local field, providing a unique signature region where electron frozen-in law is broken. The numerical predictions are confirmed by in situ Magnetospheric Multiscale spacecraft observations during at Earth's dayside magnetopause.
The coupling between a rapidly expanding cloud of ionized debris and an ambient magnetized plasma is revisited with hybrid (kinetic ion/fluid electron) simulation code that allows study over wide range parameters. Over specified hypothetical conditions, simple scaling laws in terms the total mass explosion speed are derived verified for maximal size fraction free-streams from burst along magnetic field. amount escapes minimal to background field increases gyroradius. Test cases two different...
In situ spacecraft observations within the exhausts of magnetic reconnection document a large variation in velocity space structure electron distribution function. Multiple mechanisms help govern underlying dynamics, yielding range signatures for collisionless reconnection. These include passing beams electrons separated by well-defined boundaries from betatron heated/cooled trapped electrons. The present study emphasizes how localized regions non-adiabatic dynamics can mix across...
We present a drift kinetic model for the free expansion of thermal plasma out magnetic nozzle. This problem relates to space propulsion systems, natural environments such as solar wind, and end losses from expander region mirror magnetically confined fusion concepts gas dynamic trap. The incorporates trapped passing orbit types encountered in geometry maps an upstream distribution. boundary condition quasineutrality require generation ambipolar potential drop ∼5Te/e, forming barrier...
Abstract A valid fluid model for electrons in collisionless space plasmas is desirable understanding the structure and evolution of magnetic reconnection geometries. Additionally, such a would be useful simulation systems too large to tractable fully kinetic model. Using Magnetospheric Multiscale spacecraft observations, we provide direct confirmation Lê et al., 2009 ( https://doi.org/10.1103/PhysRevLett.102.085001 ) equations state electron pressure tensor during guide field demonstrate how...
Various systems can be modeled as a point-like explosion of ionized debris into magnetized, collisionless background plasma—including astrophysical examples, active experiments in space, and laser-driven laboratory experiments. Debris streaming from the parallel to magnetic field may drive multiple resonant non-resonant ion–ion beam instabilities, some which efficiently couple energy even support formation shocks. We present large-scale hybrid (kinetic ions + fluid electrons)...
Abstract Anisotropic electron heating predictions of the equations state Le et al. (2009); https://doi.org/10.1103/PhysRevLett.102.085001 (“the EoS”) are applied to reconnection in Earth's magnetosheath. The model is applicable open systems where electrons streaming along magnetic field lines into region, sourced by fixed external reservoirs plasma ambient region. While spacecraft observations have previously shown EoS hold region near X ‐line, we find that for an event observed far...
Abstract Magnetospheric Multiscale observed an extended current layer concurrent with a strong parallel electric field. The is embedded in the reconnection exhaust and consistent magnetized jet expected roughly symmetric moderate guide field reconnection. at balances gradient electron pressure caused by transition between electrons T e ‖ > ⊥ on one side of demagnetized, isotropic across thin layer. Simulation results show how this can occur associated gradients Ohm's law balance
The recent study of signal interference circuits, which find its origins in earlier work related to active channelized filters, has introduced new methods for shaping the frequency response electrical systems. This paper seeks extend this thread research by investigating electromechanical resonators are embedded feedforward, control architectures. In particular, mathematical models developed explore behavior linear that two prototypical topologies, can exhibit a variety qualitatively...
The kinetic stability of collisionless, sloshing beam-ion (45{\deg} pitch angle) plasma is studied in a 3D simple magnetic mirror, mimicking the Wisconsin High-temperature superconductor Axisymmetric Mirror (WHAM) experiment. collisional Fokker-Planck code CQL3D-m provides slowing-down distribution to initialize kinetic-ion/fluid-electron Hybrid-VPIC, which then simulates free decay without external heating or fueling. Over 1-10 $\mu$s, drift-cyclotron loss-cone (DCLC) modes grow and...
The resonant right-hand instability (RHI) is often the dominant mode driven by reflected ions upstream of Earth’s quasi-parallel bow shock. In tradition Peter Gary, this paper further explores using numerical solutions plasma dispersion relation and non-linear kinetic simulations, with parameters inspired observations from NASA’s Magnetospheric Multiscale (MMS) mission. Agreement found between ion distributions in particle-in-cell simulations spacecraft data, which show gyrophase bunching...
In this paper, we derive a new drift-kinetic method for estimating gradients in the plasma properties through velocity space distribution at single point. The are intrinsically related to agyrotropic features of function. This predicts magnetized function, and can predict arbitrary moments gyrotropic background allows estimates on density pressure scale Larmor radius, proving resolve smaller scales than any currently available spacecraft. model is verified with set fully-kinetic VPIC...
Hybrid-VPIC is an extension of the open-source high-performance particle-in-cell (PIC) code VPIC incorporating hybrid kinetic ion/fluid electron solvers. This paper describes models that are available in and gives overview applications to space laboratory plasma physics problems. Particular choices how solvers were implemented documented for reference by users. A few solutions handling numerical complications particular codes also described. Special emphasis given computationally taxing...