A5023430385- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Geomagnetism and Paleomagnetism Studies
- Astro and Planetary Science
- Fluid Dynamics and Turbulent Flows
- Magnetic confinement fusion research
- Solar Radiation and Photovoltaics
- Stellar, planetary, and galactic studies
- Geophysics and Gravity Measurements
- Gas Dynamics and Kinetic Theory
- Laser-induced spectroscopy and plasma
- Earthquake Detection and Analysis
- Astrophysics and Star Formation Studies
- Advanced Thermodynamics and Statistical Mechanics
- Astrophysics and Cosmic Phenomena
- Particle Dynamics in Fluid Flows
- Theoretical and Computational Physics
- Lattice Boltzmann Simulation Studies
- Atmospheric Ozone and Climate
- Plasma Diagnostics and Applications
- Gamma-ray bursts and supernovae
- Climate variability and models
- Tropical and Extratropical Cyclones Research
- Wind and Air Flow Studies
- Dust and Plasma Wave Phenomena
University of Delaware
2016-2025
Goddard Space Flight Center
1981-2023
Planetary Science Institute
2010-2023
Heliophysics
2023
University of Arizona
2023
Trinity College Dublin
2023
University of California, Davis
2022
Southern University of Science and Technology
2019
University of Science and Technology of China
2019
Peking University
2019
It is known that the Frisch-Hasslacher-Pomeau lattice-gas automaton model and related models possess some rather unphysical effects. These are (1) a non-Galilean invariance caused by density-dependent coefficient in convection term, (2) velocity-dependent equation of state. In this paper, we show both these effects can be eliminated exactly lattice Boltzmann-equation model.
Measurements of the total energy, cross helicity, and magnetic helicity solar wind at 1, 2.8, 5 AU are presented. These quantities three rugged invariants three‐dimensional ideal incompressible MHD turbulence theory. The theoretical technique for measuring from matrix two‐point correlations is shown. length scales characterizing found to be equal or greater than those which characterize energy. typically lies larger correlation length, consistent with expectations inverse cascade selective...
The development of anisotropy in an initially isotropie spectrum is studied numerically for two-dimensional magnetohydrodynamic turbulence. develops through the combined effects externally imposed d.c. magnetic field and viscous resistive dissipation at high wavenumbers. effect most pronounced mechanical Reynolds numbers. greater higher
The dissipation range for interplanetary magnetic field fluctuations is formed by those with spatial scales comparable to the gyroradius or ion inertial length of a thermal ion. It reasonable assume that represents final fate energy transferred from largest via nonlinear processes until kinetic coupling background plasma removes spectrum and heats distribution. Typically, at 1 AU sets in spacecraft frame frequencies few tenths hertz. characterized steepening power often demonstrates bias...
A numerical method, based on a discrete Boltzmann equation, is presented for solving the equations of magnetohydrodynamics (MHD). The algorithm provides advantages similar to cellular automaton method in that it local and easily adapted parallel computing environments. Because much lower noise levels less stringent requirements lattice size, appears be more competitive with traditional solution methods. Examples show model accurately reproduces both linear nonlinear MHD phenomena.
view Abstract Citations (605) References (86) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Proton and Electron Mean Free Paths: The Palmer Consensus Revisited Bieber, John W. ; Matthaeus, William H. Smith, Charles Wanner, Wolfgang Kallenrode, May-Britt Wibberenz, Gerd We present experimental theoretical evidence suggesting that the mean free path of cosmic-ray electrons protons may be fundamentally different at low to intermediate (less than 50 MV)...
Two new methods for distinguishing two‐dimensional (2D) turbulence from slab are applied to Helios magnetometer data. Two‐component models with varying and 2D ingredients considered. Both indicate that solar wind magnetic possesses a dominant (∼85 % by energy) component. The presence of such large component provides natural solution the long‐standing problem “too small” cosmic ray mean free paths derived quasilinear scattering theory when using model.
The fluctuations in magnetic field and plasma velocity the solar wind possess many features expected of fully developed magnetohydrodynamic turbulence. Understanding this nonlinear system is complicated by dynamical effects shear between fast slow streams, spherical expansion wind, its compressibility. Direct spacecraft observations from 0.3 to over 20 AU, radio scintillation plasmas near Sun, numerical simulations, various models provide complementary methods that have shown convincingly...
A nonlinear theory of the perpendicular diffusion charged particles is presented, including influence parallel scattering and dynamical turbulence. The shows encouraging agreement with numerical simulations.
Using hour‐averaged data from the Helios and Voyager spacecraft, we have investigated origin evolution of low‐frequency interplanetary fluctuations 0.3 to 20 AU. Alfvénic in inner solar system are found be generally outward traveling Sun at times quite pure, general agreement with previous work. The correlation between velocity magnetic field can high even on scales longer than transit time indicating a for initial waves. However, become substantially less by 1 AU, larger evolving more...
An unsolved problem in plasma turbulence is how energy dissipated at small scales. Particle collisions are too infrequent hot plasmas to provide the necessary dissipation. Simulations either treat fluid scales and impose an ad hoc form of dissipation (e.g., resistivity) or consider arising from resonant damping amplitude disturbances where rates found be comparable that predicted linear theory. Here, we report kinetic simulations span macroscopic down motion electrons. We find turbulent...
The magnetometer instrument on the Solar Orbiter mission is designed to measure magnetic field local spacecraft continuously for entire duration. need characterise not only background but also its variations scales from far above well below proton gyroscale result in challenging requirements stability, precision, and noise, as operational limitations both other instruments. vibration thermal environment has led significant development of mechanical sensor design. overall design, performance,...
The Integrated Science Investigation of the Sun (ISIS) is a complete science investigation on Solar Probe Plus (SPP) mission, which flies to within nine solar radii Sun’s surface. ISIS comprises two-instrument suite measure energetic particles over very broad energy range, as well coordinated management, operations, data processing, and scientific analysis. Together, observations allow us explore mechanisms dynamics, including their: (1) Origins—defining seed populations physical conditions...
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...
One of the most striking observations made by Parker Solar Probe during its first solar encounter is omnipresence rapid polarity reversals in a magnetic field that otherwise mostly radial. These so-called switchbacks strongly affect dynamics field. We concentrate here on their macroscopic properties. First, we find these structures are self-similar, and have neither characteristic magnitude, nor duration. Their waiting time statistics shows evidence for aggregation. The associated long...
Abstract Launched on 12 Aug. 2018, NASA’s Parker Solar Probe had completed 13 of its scheduled 24 orbits around the Sun by Nov. 2022. The mission’s primary science goal is to determine structure and dynamics Sun’s coronal magnetic field, understand how solar corona wind are heated accelerated, what processes accelerate energetic particles. returned a treasure trove data that far exceeded quality, significance, quantity expectations, leading significant number discoveries reported in nearly...
On the basis of transport theories appropriate to a radially expanding solar wind, new results for evolution energy density in wind fluctuations at MHD scales are derived. The models, which represent departure from well‐known WKB description, include effects “mixing”, driving by stream‐stream interactions (compression and shear) interstellar pick‐up ions as well non‐isotropic turbulence. Magnetometer data Voyager 1 2 Pioneer 11 compared turbulence‐based models close agreement is found...
Building on results from two-dimensional magnetohydrodynamic (MHD) turbulence (Shebalin, Matthaeus & Montgomery 1983), the development of anisotropic states initially isotropic ones is investigated numerically for fully three-dimensional incompressible MHD turbulence. It found that when an external d.c. magnetic field ( B 0 ) imposed viscous and resistive systems, excitations are preferentially transferred to modes with wavevectors perpendicular ). The anisotropy increases increasing...
A candidate mechanism for the heating of solar corona in open field line regions is described. The interaction Alfvén waves, generated photosphere or chromosphere, with their reflections and subsequent driving quasi-two-dimensional MHD turbulence considered. nonlinear cascade drives fluctuations toward short wavelengths which are transverse to mean field, thereby at rates insensitive restrictive timescales. phenomenology presented, providing estimates achievable efficiency that most favorable.
The theory of nearly incompressible (NI) fluid dynamics developed previously for hydrodynamics is extended to magnetohydrodynamics (MHD). On the basis a singular expansion technique, modified systems equations are derived which effects compressibility admitted only weakly in terms different possible solutions (thus ‘‘nearly MHD’’). NI MHD represents interface between compressible and magnetofluid descriptions subsonic regime. here does not hold presence very large thermal, gravitational, or...
The magnetic field and plasma data collected by the Voyager spacecraft between 1 11 AU are used to study properties of interplanetary MHD fluctuations attempt answer several related questions about Alfvénicity solar wind fluctuations: First, what extent velocity Alfvénic? Second, does dominant propagation direction Alfvénic evolve with heliocentric distance? Third, is presence correlated large‐scale structures, such as stream interaction regions? In addition, we investigated contributions...
We test a theory presented previously to account for the turbulent transport of magnetic fluctuation energy in solar wind and related dissipation heating ambient ion population. This accounts injection through damping large‐scale flow gradients, such as shear compression, incorporates due wave excitation by interstellar pickup ions. The assumes quasi‐two‐dimensional spectral subsequent that heats thermal protons. compare predictions this with Voyager 2 Pioneer 11 observations energy,...
Using 5 years of spacecraft data from near Earth orbit, we investigate the correlation anisotropy solar wind magnetohydrodynamic-scale fluctuations and show that nature differs in fast (>500 km s-1) slow (<400 streams. In particular, streams are relatively more dominated by with wavevectors quasi-parallel to local magnetic field, while streams, which appear be fully evolved turbulence, quasi-perpendicular fluctuation wavevectors.