A5059149464- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Geomagnetism and Paleomagnetism Studies
- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Magnetic confinement fusion research
- Geophysics and Gravity Measurements
- Solar Radiation and Photovoltaics
- Earthquake Detection and Analysis
- Fluid Dynamics and Turbulent Flows
- Market Dynamics and Volatility
- Tropical and Extratropical Cyclones Research
- Atmospheric Ozone and Climate
- Planetary Science and Exploration
- Laser-induced spectroscopy and plasma
- Dust and Plasma Wave Phenomena
- Plasma Diagnostics and Applications
- Gas Dynamics and Kinetic Theory
- Particle accelerators and beam dynamics
- Oceanographic and Atmospheric Processes
- Global Energy and Sustainability Research
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- High-pressure geophysics and materials
- Magnetic Field Sensors Techniques
Space Science Institute
2017-2024
University of Maryland, Baltimore County
2016-2023
Heliophysics
2012-2022
University of Maryland, Baltimore
2019-2022
Bowie State University
2022
Goddard Space Flight Center
2012-2021
École Polytechnique
2013
Laboratoire de Physique des Plasmas
2013
Centre National de la Recherche Scientifique
2013
Peking University
2010
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...
Abstract. The Cluster mission, ESA’s first cornerstone project, together with the SOHO dating back to proposals in 1982, was finally launched summer of 2000. On 16 July and 9 August, respectively, two Russian Soyuz rockets blasted off from cosmodrome Baikonour deliver spacecraft, each into their proper orbit. By end August 2000, four satellites had reached final tetrahedral constellation. commissioning 44 instruments, both individually as an ensemble complementary tools, completed five...
We report the first direct determination of dissipation range magnetofluid turbulence in solar wind at electron scales. Combining high resolution magnetic and electric field data Cluster spacecraft, we computed spectrum found two distinct breakpoints 0.4 35 Hz, which correspond, respectively, to Doppler-shifted proton gyroscales, ${f}_{{\ensuremath{\rho}}_{p}}$ ${f}_{{\ensuremath{\rho}}_{e}}$. Below ${f}_{{\ensuremath{\rho}}_{p}}$, follows a Kolmogorov scaling ${f}^{\ensuremath{-}1.62}$,...
We show the first three dimensional (3D) dispersion relations and k spectra of magnetic turbulence in solar wind at subproton scales. used Cluster data with short separations applied k-filtering technique to frequency range where transition scales occurs. that cascade is carried by highly oblique kinetic Alfvén waves ω(plas) ≤ 0.1ω(ci) down k(⊥) ρ(i)∼2. Each spectrum direction perpendicular B0 shows two scaling ranges separated a breakpoint (in interval [0.4,1]k(⊥)ρ(i): Kolmogorov k(⊥)⁻¹ⁱ⁷...
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...
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 linear theory of electromagnetic instabilities driven by an energetic ion beam streaming parallel to a magnetic field in homogeneous Vlasov plasma is considered. Numerical solutions the full dispersion equation are presented. At propagation field, there four distinct instabilities. A sufficiently gives rise two unstable modes with right-hand polarization, one resonant beam, other nonresonant. large T⊥/T∥ left-hand cyclotron anisotropy instability at relatively small velocities, and hot...
Large‐amplitude (up to ∼50 mV/m) solitary waves, identified as electron holes, have been observed during waveform captures on two of the four Cluster satellites several plasma sheet encounters that passage a magnetotail reconnection x line. The holes were seen near outer edge sheet, within and density cavity, at distances order few ion inertial lengths from center current sheet. occur intervals when there narrow beams but not distributions more isotropic or contained broad in pitch angle....
Spacecraft observations of the interplanetary magnetic field at 1 AU (astronomical unit) are shown to have frequency spectra with a $\frac{1}{f}$ dependence in range 2.7 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}6}$ 8.0 ${10}^{\ensuremath{-}5}$ Hz. We suggest that spectrum results from superposition uncorrelated samples solar surface turbulence log-normal distributions correlation lengths corresponding scale-invariant distribution times over an appropriate parameters.
We investigated the inertial and dissipation ranges of reduced magnetic helicity spectrum solar wind fluctuations have found that this appears insensitive to cycle variations changes in flow parameters. In range spectrum, is large but random independent heliocentric distance between 0.3 10 AU. At small scales, a correlation exist average value normalized polarity sectors, suggesting these fluctuations, if outward propagating, are predominantly right‐hand polarized. statistical properties...
We use a two‐dimensional, incompressible MHD spectral code to establish that shear‐driven turbulence is possible means for producing many observed properties of the evolution magnetic and velocity fluctuations in solar wind and, particular, cross helicity (“Alfvénicity”) at small scales. find large‐scale shear can nonlinearly produce cascade smaller scale even when linear Kelvin‐Helmholtz mode stable roughly power law inertial range established by this process. While thus produced are not...
Kinetic and magnetic energy spectra in the ecliptic plane near 1 AU are found to exhibit different power-law behaviors inertial range, with spectrum often having a exponent 5/3 kinetic 3/2 (the range extends from approximately 5 × 10-4 10-1 Hz). The total energy, plus magnetic, has that lies between 5/3, value 1.6. Alfvén ratio, ratio of is be slowly increasing function frequency roughly 0.5 0.9 10-3 Hz. These conclusions based on analysis four distinct time intervals solar wind field plasma...
A technique is presented for the measurement of magnetic helicity from values two-point magnetic-field correlation matrix under assumption spatial homogeneity. Knowledge a single scalar function space, derivable matrix, suffices to determine helicity. The illustrated by report first solar wind.
view Abstract Citations (172) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Stabilization of Electron Streams in Type III Solar Radio Bursts Papadopoulos, Konstantinos ; Goldstein, Melvyn L. Smith, Robert A. We show that the electron streams give rise to type solar radio bursts are stable and will not be decelerated while propagating out corona. The stabilization mechanism depends on parametric oscillating two-stream instability. Radiation...
From an analysis of magnetohydrodynamic turbulent processes, the authors conclude that frequent observation outward-propagating Alfv\'enic fluctuations in solar wind can arise from early states situ evolution, and need not reflect coronal processes as has hitherto been assumed.
Solar wind research and studies of charged particle propagation often assume that the interplanetary magnetic field represents a stationary random process. In this paper we investigate extent to which ensemble averages solar fields follow asymptotic behavior predicted by ergodic theorem. Several time periods, including span nearly two years, are analyzed. Data intervals many rotations found satisfy conditions ‘weak’ stationarity if effects rotation included in analysis. Shorter intervals,...
Low-density astrophysical plasmas may be described by magnetohydrodynamics at large scales, but require kinetic description ion scales in order to include dissipative processes that terminate the cascade. Here plasma simulations and high-resolution spacecraft observations are compared facilitate interpretation of signatures various dissipation mechanisms. Kurtosis increments indicates scale coherent structures present, with some suggestion incoherent activity near scales. Conditioned proton...
Recent observations of the solar wind have pointed out existence a cascade magnetic energy from scale proton Larmor radius ${\ensuremath{\rho}}_{p}$ down to electron ${\ensuremath{\rho}}_{e}$ scale. In this Letter we study spatial properties field fluctuations in and find that at small scales does not resemble sea homogeneous fluctuations, but rather two-dimensional plane containing thin current sheets discontinuities with sizes ranging $l\ensuremath{\gtrsim}{\ensuremath{\rho}}_{p}$ below....
We have developed a three-fluid, three-dimensional magnetohydrodynamic solar wind model that incorporates turbulence transport, eddy viscosity, turbulent resistivity, and heating. The plasma is described as system of co-moving protons, electrons, interstellar pickup with separate energy equations for each species. Numerical steady-state solutions Reynolds-averaged coupled transport energy, cross helicity, correlation length are obtained by the time relaxation method in corotating Sun frame...
We report unambiguous in situ observation of the coalescence macroscopic flux ropes by magnetospheric multiscale (MMS) mission. Two coalescing with sizes $\ensuremath{\sim}1\text{ }\text{ }{R}_{E}$ were identified at subsolar magnetopause occurrence an asymmetric quadrupolar signature normal component magnetic field measured MMS spacecraft. An electron diffusion region (EDR) a width four local inertial lengths was embedded within merging current sheet. The EDR characterized intense parallel...