A5072348671- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- Magnetic confinement fusion research
- Planetary Science and Exploration
- Fluid Dynamics and Turbulent Flows
- Geophysics and Gravity Measurements
- Laser-induced spectroscopy and plasma
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Solar Radiation and Photovoltaics
- Tropical and Extratropical Cyclones Research
- Gas Dynamics and Kinetic Theory
- Dust and Plasma Wave Phenomena
- Stellar, planetary, and galactic studies
- Lightning and Electromagnetic Phenomena
- Particle accelerators and beam dynamics
- High-pressure geophysics and materials
- Particle Accelerators and Free-Electron Lasers
- Computational Fluid Dynamics and Aerodynamics
- Earthquake Detection and Analysis
- Space Science and Extraterrestrial Life
- Ocean Waves and Remote Sensing
- Gamma-ray bursts and supernovae
Czech Academy of Sciences, Institute of Atmospheric Physics
2015-2024
Czech Academy of Sciences, Astronomical Institute
2015-2024
Imperial College London
2011-2024
Astronomical Institute of the Slovak Academy of Sciences
2011-2020
University of Delaware
2020
Czech Academy of Sciences
2007-2019
Observatoire de la Côte d’Azur
2009-2010
Centre National de la Recherche Scientifique
2009-2010
Space Research Institute
2009-2010
Jet Propulsion Laboratory
2010
We present a comparison between WIND/SWE observations (Kasper et al., 2006) of β ∥ p and T ⊥ / (where is the proton parallel beta are perpendicular temperatures, respectively; here indicate directions with respect to ambient magnetic field) predictions Vlasov linear theory. In slow solar wind, observed temperature anisotropy seems be constrained by oblique instabilities, mirror one fire hose, contrary results theory which predicts dominance cyclotron instability hose. The fast wind core...
We report an analysis of the proton temperature anisotropy evolution from 0.3 to 2.5 AU based on Helios and Ulysses observations. With increasing distance fast wind data show a path in parameter space ( β ∥ p , T ⊥ / ). The first part trajectory is well described by anticorrelation between parallel beta, while after 1 with changes result agreement constraints derived fire hose instability. slow more irregular behavior, general it not possible recover single path. However, small temporal...
The Radio and Plasma Waves (RPW) instrument on the ESA Solar Orbiter mission is described in this paper. This designed to measure in-situ magnetic electric fields waves from continuous a few hundreds of kHz. RPW will also observe solar radio emissions up 16 MHz. primary importance science requirements since it essential answer three four overarching objectives. In addition exchange on-board data with other instruments order process algorithms for interplanetary shocks type III langmuir detections.
The proton thermal energetics in the slow solar wind between 0.3 and 1 AU is reinvestigated using Helios 2 data, complementing a similar analysis for fast [Hellinger et al., 2011]. results winds are compared discussed context of previous results. Protons need to be heated perpendicular direction with respect ambient magnetic field from AU. In parallel direction, protons cooled at AU, cooling rate comparable corresponding heating rate; required decreases until transition occurs: by require...
[1] The proton thermal energetics in the fast solar wind between 0.3 and 1 AU is reinvestigated using Helios 2 data. Closer to Sun, it estimated that, account for observed radial profiles of parallel perpendicular temperature, nonnegligible cooling heating are necessary. Around needed both directions. We also calculate corresponding rates find that total significant interplanetary necessary, agreement with previous results. possible influence deceleration streams due interaction slow ones...
Spectral properties of the turbulent cascade from fluid to kinetic scales in collisionless plasmas are investigated by means large-size three-dimensional (3D) hybrid (fluid electrons, protons) particle-in-cell simulations. Initially isotropic Alfvènic fluctuations rapidly develop a strongly anisotropic cascade, mainly direction perpendicular ambient magnetic field. The omnidirectional field spectrum shows double power-law behavior over almost two decades wavenumber, with Kolmogorov-like...
An analysis of ion non‐thermal properties in the fast solar wind based on Ulysses data is reported. The radial evolution main proton moments (density, temperature, and drift velocities) their empirical correlations with other plasma parameters are investigated detail compared theoretical expectations. stability studied against different kinetic instabilities driven by temperature anisotropies differential velocities, focusing identification possible signatures relevant observed core‐beam...
We investigate properties of plasma turbulence from magneto-hydrodynamic (MHD) to sub-ion scales by means two-dimensional, high-resolution hybrid particle-in-cell simulations. impose an initial ambient magnetic field, perpendicular the simulation box, and we add a spectrum large-scale kinetic fluctuations, with energy equipartition vanishing correlation. Once is fully developed, observe MHD inertial range, where spectra field proton bulk velocity fluctuations exhibit power-law scaling...
Abstract A new path for the generation of a sub-ion-scale cascade in collisionless space and astrophysical plasma turbulence, triggered by magnetic reconnection, is uncovered means high-resolution two-dimensional hybrid-kinetic simulations employing two complementary approaches, Lagrangian Eulerian, different driving mechanisms. The simulation results provide clear numerical evidence that development power-law energy spectra below so-called ion break occurs as soon first reconnection events...
We present results from a high-resolution and large-scale hybrid (fluid electrons particle-in-cell protons) two-dimensional numerical simulation of decaying turbulence. Two distinct spectral regions (separated by smooth break at proton scales) develop with clear power-law scaling, each one occupying about decade in wave numbers. The exhibit simultaneously several properties the observed solar wind fluctuations: indices magnetic, kinetic, residual energy spectra magneto-hydrodynamic (MHD)...
Abstract A dynamical vectorial equation for homogeneous incompressible Hall-magnetohydrodynamic (MHD) turbulence together with the exact scaling law third-order correlation tensors, analogous to that MHD, is rederived and applied results of two-dimensional hybrid simulations plasma turbulence. At large scales exhibit a clear inertial range where MHD dynamic valid. In sub-ion cascade continues via Hall term, but derived in framework Hall-MHD equations obtained only low beta simulation. For...
We present estimates of the turbulent energy-cascade rate derived from a Hall-magnetohydrodynamic (MHD) third-order law. compute contribution Hall term and MHD to energy flux. Magnetospheric Multiscale (MMS) data accumulated in magnetosheath solar wind are compared with previously established simulation results. Consistent simulations, we find that at large scales, MMS observations exhibit clear inertial range dominated by In subion range, cascade continues diminished level via term, change...
We investigate properties of large-scale solar wind Alfvénic fluctuations and their evolution during radial expansion. assume a strictly background magnetic field B∥R, we use two-dimensional hybrid (fluid electrons, kinetic ions) simulations balanced turbulence in the plane orthogonal to B; simulated plasma evolves system comoving with (i.e., expanding box approximation). Despite some model limitations, exhibit important observed plasma: Magnetic evolve toward state low-amplitude variations...
Exploration of space plasmas is entering a new era multi-satellite constellation measurements that will determine fundamental properties turbulence, with unprecedented precision. Familiar but imprecise approximations must be abandoned and replaced more advanced approaches. We present the novel multispacecraft technique LPDE (Lag-Polyhedra Derivative Ensemble) for evaluating third-order statistics, using simultaneous at many points. The method differs from existing approaches in (i) it...
We investigate properties of ideal second-order magneto-hydrodynamic (MHD) and Hall MHD invariants  (kinetic+magnetic energy different helicities) in a two-dimensional hybrid simulation decaying plasma turbulence. The combined (kinetic+magnetic) decays at large scales, cascades (from to small scales) via the non-linearity intermediate scales. This cascade partly continues coupling sub-ion cascading is transferred (dissipated) internal scales resistive  dissipation...
Electromagnetic fluctuations in the solar wind cover a wide range of scales, from sun-rotation period to sub-electron scales. We study Cluster Guest Investigator data when 2 satellites were at 7 km distance, that corresponds few electron Larmor radius. find typical spectral shape within kinetic and signatures intermittency up Local analysis magnetic scales indicates presence vortex-like coherent structures, which can be interpreted terms scale Alfven vortices. discuss possible connection...
Two instabilities could take place in plasma with a bi‐Maxwellian proton distribution function T p ‖ > ⊥, where and ⊥ are temperatures, parallel perpendicular, respectively, to the background magnetic field. The first instability is fire hose (or whistler hose), generating low‐frequency waves at propagation. We found new, second instability, Alfvén hose, that generates zero‐frequency of branch strongly oblique has linear growth rate comparable or even greater than hose. two same initial...
We report a study of the properties parallel proton fire hose instability comparing results obtained by linear analysis, from one‐dimensional (1‐D) standard hybrid simulations and 1‐D expanding box simulations. The three different approaches converge toward same threshold condition which is in good agreement with situ observations, suggesting that such relevant solar wind context. investigate also effect wave‐particle interactions on shaping distribution function evolution spectrum magnetic...
Oblique fire hose instability is investigated using hybrid simulations for proton betas of the order one and parallel temperatures sufficiently greater than perpendicular ones. The confirm previous simulation results showing that this has self‐destructing properties efficiently reduces temperature anisotropy. A parametric study one‐dimensional standard shows stronger changes in anisotropy wave emissions appear larger initial anisotropies. An ideal, slow plasma expansion, modeled by a...
A linear threshold condition of the mirror instability in a homogeneous, multispecies collisionless plasma with general class distribution functions is obtained low-frequency, long-wavelength limit Vlasov-Maxwell equation. In case one cold species, conditions validity and behavior near are also presented. It confirmed that finite Larmor radius effects do not change condition. The extended to hot species functions. this or hard get analytically. Previous analytical numerical results discussed.
Abstract. Using 5 years of Cluster data, we present a detailed statistical analysis magnetic fluctuations associated with mirror structures in the magnetosheath. We especially focus on shape these which, addition to quasi-sinusoidal forms, also display deep holes and high peaks. The occurrence frequency most probable location various types is discussed, together their relation local plasma parameters. While properties have previously been correlated β plasma, emphasize here influence...
Two‐dimensional particle‐in‐cell (PIC) simulations are used for analyzing in detail different nonstationary behaviors of a perpendicular supercritical shock. A recent study by Hellinger et al. (2007) has shown that the front shock can be dominated emission large‐amplitude whistler waves. These waves inhibit self‐reformation driven reflected ions; then, appears almost “quasi‐stationary.” The present stresses new complementary results. First, fixed β i value, (WWE) persists high M above...