Origins and Evolution of the Electron and Ion Populations of the Magnetopause’s Boundary Layers

2020 ◽  
Author(s):  
Jean Berchem ◽  
Giovanni Lapenta ◽  
Robert Richard ◽  
William Paterson ◽  
C. Philippe Escoubet
Keyword(s):  
Boundary Layers ◽  
Three Dimensional ◽  
Distribution Functions ◽  
Current Layer ◽  
Filamentary Structure ◽  
Particle In Cell ◽  
Reconnection Region ◽  
Dayside Magnetopause ◽  
Velocity Distribution Functions ◽  
Multiscale Structures

<p>Increasingly sophisticated instruments and simulations have revealed a wide variety of plasma processes and multiscale structures at the dayside magnetopause. In this presentation, we focus on the origins and evolution of the plasma populations observed in the magnetopause boundary layers. We present the results of Particle-In-Cell (PIC) simulations encompassing large volumes of the dayside magnetosphere. The implicit 3D PIC code used in the study was initialized from a global MHD state of the magnetosphere for southward interplanetary field conditions.  Three-dimensional plots of the perpendicular slippage indicates that reconnection occurs over most of the dayside magnetopause. However, the simulation reveals that the reconnection region has a much more filamentary structure than the X-line expected from the extrapolation of 2D models and that multiscale structures thread the reconnection outflow. In particular, the simulation indicates the formation of multiple layers of electrons with significant field-aligned velocities along the main magnetopause current layer. We use velocity distribution functions at different locations in the reconnection outflow to characterize the origins and evolution of the electron and ionpopulations of the magnetosheath and magnetospheric boundary layers and compare them with observations from the MMS and Cluster spacecraft.</p>

scholarly journals Cluster observations of the high-latitude magnetopause and cusp: initial results from the CIS ion instruments

2001 ◽  
Vol 19 (10/12) ◽  
pp. 1545-1566 ◽  
Author(s):  
J. M. Bosqued ◽  
T. D. Phan ◽  
I. Dandouras ◽  
C. P. Escoubet ◽  
H. Rème ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Boundary Layers ◽  
High Latitude ◽  
Three Dimensional ◽  
Distribution Functions ◽  
Current Layer ◽  
Transfer Event ◽  
Normal Speed ◽  
Field Lines ◽  
The Imf

Abstract. Launched on an elliptical high inclination orbit (apogee: 19.6 RE) since January 2001 the Cluster satellites have been conducting the first detailed three-dimensional studies of the high-latitude dayside magnetosphere, including the exterior cusp, neighbouring boundary layers and magnetopause regions. Cluster satellites carry the CIS ion spectrometers that provide high-precision, 3D distributions of low-energy (<35 keV/e) ions every 4 s. This paper presents the first two observations of the cusp and/or magnetopause behaviour made under different interplanetary magnetic field (IMF) conditions. Flow directions, 3D distribution functions, density profiles and ion composition profiles are analyzed to demonstrate the high variability of high-latitude regions. In the first crossing analyzed (26 January 2001, dusk side, IMF-BZ < 0), multiple, isolated boundary layer, magnetopause and magnetosheath encounters clearly occurred on a quasi-steady basis for ~ 2 hours. CIS ion instruments show systematic accelerated flows in the current layer and adjacent boundary layers on the Earthward side of the magnetopause. Multi-point analysis of the magnetopause, combining magnetic and plasma data from the four Cluster spacecraft, demonstrates that oscillatory outward-inward motions occur with a normal speed of the order of ± 40 km/s; the thickness of the high-latitude current layer is evaluated to be of the order of 900–1000 km. Alfvénic accelerated flows and D-shaped distributions are convincing signatures of a magnetic reconnection occurring equatorward of the Cluster satellites. Moreover, the internal magnetic and plasma structure of a flux transfer event (FTE) is analyzed in detail; its size along the magnetopause surface is ~ 12 000 km and it convects with a velocity of ~ 200 km/s. The second event analyzed (2 February 2001) corresponds to the first Cluster pass within the cusp when the IMF-BZ component was northward directed. The analysis of relevant CIS plasma data shows temporal cusp structures displaying a reverse energy-latitude "saw tooth" dispersion, typical for a bursty reconnection between the IMF and the lobe field lines. The observation of D-shaped distributions indicates that the Cluster satellites were located just a few RE from the reconnection site.Key words. Magnetospheric physics (magnetopause, cusp, and boundary layers; magnetosheath) Space plasma physics (magnetic reconnection)

scholarly journals Observations of diffusion in the electron halo and strahl

2016 ◽  
Vol 34 (12) ◽  
pp. 1175-1189 ◽  
Author(s):  
Chris Gurgiolo ◽  
Melvyn L. Goldstein
Keyword(s):  
Magnetic Field ◽  
Energy Range ◽  
Lower Energy ◽  
Three Dimensional ◽  
Distribution Functions ◽  
Electron Velocity ◽  
Electron Velocity Distribution ◽  
Velocity Distribution Functions ◽  
The Magnetic Field ◽  
Solar Wind Electron

Abstract. Observations of the three-dimensional solar wind electron velocity distribution functions (VDF) using ϕ–θ plots often show a tongue of electrons that begins at the strahl and stretches toward a new population of electrons, termed the proto-halo, that exists near the projection of the magnetic field opposite that associated with the strahl. The energy range in which the tongue and proto-halo are observed forms a “diffusion zone”. The tongue first appears in energy generally near the lower-energy range of the strahl and in the absence of any clear core/halo signature. While the ϕ–θ plots give the appearance that the tongue and proto-halo are derived from the strahl, a close examination of their density suggests that their source is probably the upper-energy core/halo electrons which have been scattered by one or more processes into these populations.

Dispersion relation for electrostatic waves in plasmas with isotropic and anisotropic Kappa distributions for electrons and ions

2017 ◽  
Vol 83 (5) ◽  
Author(s):  
L. F. Ziebell ◽  
R. Gaelzer ◽  
F. J. R. Simões
Keyword(s):  
Dispersion Relation ◽  
Dispersion Relations ◽  
Distribution Functions ◽  
Sound Waves ◽  
Kappa Index ◽  
Langmuir Waves ◽  
Electrostatic Waves ◽  
Particle In Cell ◽  
Significant Difference ◽  
Velocity Distribution Functions

Velocity distribution functions which feature extended tails with power-law dependence have been consistently observed in the solar wind environment and are frequently modelled by the so-called Kappa distributions. Different forms of Kappa distributions are commonly employed in analytical studies, and despite their similarities, they can produce different effects on the dispersion properties that occur in a plasma. We consider two different and widely used forms of Kappa distributions, in both isotropic and anisotropic cases, and systematically discuss their effects on the dispersion relations of Langmuir and ion-sound waves. It is shown that in the case of Langmuir waves, one of the forms leads to the expression for the Bohm–Gross dispersion relation, valid for plasmas with Maxwellian velocity distributions, while the other form of Kappa functions leads to a dispersion relation with significant difference regarding the Maxwellian case, particularly in the case of small values of the kappa index. For ion-sound waves, the dispersion relations obtained with the different forms of Kappa distributions are different among themselves, and also different from the Maxwellian case, with difference which increases for small values of the kappa index. Some results obtained from numerical solution of the dispersion relations are presented, which illustrate the magnitude of the perceived differences. Some results obtained with relativistic particle-in-cell simulations are also presented, which allow the comparison between the dispersion relations obtained from analytical calculations and the frequency–wavelength distribution of wave fluctuations which are observed in numerical experiments.

On the multifractality of plasma turbulence in the solar wind

2019 ◽  
Vol 15 (S354) ◽  
pp. 371-374
Author(s):  
Sebastián Echeverría ◽  
Pablo S. Moya ◽  
Denisse Pastén
Keyword(s):  
Solar Wind ◽  
Velocity Distribution ◽  
Distribution Functions ◽  
Fluctuation Analysis ◽  
Magnetic Fluctuations ◽  
Multifractal Detrended Fluctuation Analysis ◽  
Particle In Cell ◽  
Velocity Distribution Functions ◽  
Detrended Fluctuation

AbstractIn this work we have analyzed turbulent plasma in the kinetic scale by the characterization of magnetic fluctuations time series. Considering numerical Particle-In-Cell (PIC) simulations we apply a method known as MultiFractal Detrended Fluctuation Analysis (MFDFA) to study the fluctuations of solar-wind-like plasmas in thermodynamic equilibrium (represented by Maxwellian velocity distribution functions), and out of equilibrium plasma represented by Tsallis velocity distribution functions, characterized by the kappa (κ) parameter, to stablish relations between the fractality of magnetic fluctuation and the kappa parameter.

scholarly journals Hydrodynamic and Thermodynamic Nonequilibrium Effects around Shock Waves: Based on a Discrete Boltzmann Method

Entropy ◽  
2020 ◽  
Vol 22 (12) ◽  
pp. 1397
Author(s):  
Chuandong Lin ◽  
Xianli Su ◽  
Yudong Zhang
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Local Equilibrium ◽  
Nonequilibrium Statistical Mechanics ◽  
Three Dimensional ◽  
Distribution Functions ◽  
Velocity Distribution Functions ◽  
Nonequilibrium Effects ◽  
Boltzmann Method ◽  
Boltzmann Model

A shock wave that is characterized by sharp physical gradients always draws the medium out of equilibrium. In this work, both hydrodynamic and thermodynamic nonequilibrium effects around the shock wave are investigated using a discrete Boltzmann model. Via Chapman–Enskog analysis, the local equilibrium and nonequilibrium velocity distribution functions in one-, two-, and three-dimensional velocity space are recovered across the shock wave. Besides, the absolute and relative deviation degrees are defined in order to describe the departure of the fluid system from the equilibrium state. The local and global nonequilibrium effects, nonorganized energy, and nonorganized energy flux are also investigated. Moreover, the impacts of the relaxation frequency, Mach number, thermal conductivity, viscosity, and the specific heat ratio on the nonequilibrium behaviours around shock waves are studied. This work is helpful for a deeper understanding of the fine structures of shock wave and nonequilibrium statistical mechanics.

scholarly journals Cluster PEACE observations of electrons during magnetospheric flux transfer events

2001 ◽  
Vol 19 (10/12) ◽  
pp. 1509-1522 ◽  
Author(s):  
C. J. Owen ◽  
A. N. Fazakerley ◽  
P. J. Carter ◽  
A. J. Coates ◽  
I. C. Krauklis ◽  
...  
Keyword(s):  
Boundary Layers ◽  
Plasma Electron ◽  
Local Times ◽  
Current Layer ◽  
Flux Tubes ◽  
Flux Transfer Events ◽  
Dayside Magnetopause ◽  
Flux Gate ◽  
Flux Transfer ◽  
Open Flux

Abstract. During the first quarter of 2001 the apogees of the Cluster spacecraft quartet precessed through midday local times. This provides the first opportunity for 4 spacecraft studies of the bow shock, magnetosheath and the dayside magnetopause current layer and boundary layers. In this paper, we present observations of electrons in the energy range ~ 10 eV–26 keV made by the Plasma Electron And Current Experiment (PEACE) located just inside the magnetopause boundary, together with supporting observations by the Flux Gate Magnetometer (FGM). During these observations, the spacecraft have separations of ~ 600 km. This scale size is of the order or less than the typical size of flux transfer events (FTEs), which are expected to be observed following bursts of reconnection on the dayside magnetopause. We study, in detail, the 3-D configuration of electron populations observed around a series of enhancements of magnetosheath-like electrons which were observed within the magnetosphere on 2 February 2001. We find that individual spacecraft observe magnetic field and electron signatures that are consistent with previous observations of magnetospheric FTEs. However, the differences in the signatures between spacecraft indicate that these FTEs have substructure on the scale of the spacecraft separation. We use these differences and the timings of the 4 spacecraft observations to infer the motions of the electron populations and thus the configuration of these substructures. We find that these FTEs are moving from noon towards dusk. The inferred size and speed of motion across the magnetopause, in one example, is ~ 0.8 RE and ~ 70 km s-1 respectively. In addition, we observe a delay in and an extended duration of the signature at the spacecraft furthest from the magnetopause. We discuss the implications of these 4 spacecraft observations for the structure of these FTEs. We suggest that these may include a compression of the closed flux tubes ahead of the FTE, which causes density and field strength enhancements; a circulation of open flux tubes within the FTE itself, which accounts for the delay in the arrival of the magnetosheath electron populations at locations deepest within the magnetosphere; and a possible trapping of magnetospheric electrons on the most recently opened flux tubes within the FTE.Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; solar wind - magnetosphere interactions)

scholarly journals Beam tracking strategies for fast acquisition of solar wind velocity distribution functions with high energy and angular resolutions

2018 ◽  
Author(s):  
Johan De Keyser ◽  
Benoit Lavraud ◽  
Lubomir Přech ◽  
Eddy Neefs ◽  
Sophie Berkenbosch ◽  
...  
Keyword(s):  
Solar Wind ◽  
Velocity Distribution ◽  
Energy Resolution ◽  
Three Dimensional ◽  
High Energy ◽  
Distribution Functions ◽  
Acquisition Rate ◽  
Ion Distributions ◽  
Velocity Distribution Functions ◽  
Beam Tracking

Abstract. Space plasma spectrometers have often relied on spacecraft spin to collect three-dimensional particle velocity distributions, which simplifies the instrument design and reduces its resource budgets, but limits the velocity distribution acquisition rate. This limitation can in part be overcome by a the use of electrostatic deflectors at the entrance of the analyser. By mounting such a spectrometer on a sun-pointing spacecraft, solar wind ion distributions can be acquired at a much higher rate because the solar wind ion population, which is a cold beam that fills only part of the sky around its mean arrival direction, always remains in view. The present paper demonstrates how the operation of such an instrument can be optimized through the use of beam tracking strategies. The underlying idea is that it is much more efficient to cover only that part of the energy spectrum and those arrival directions where the solar wind beam is expected to be. The advantages of beam tracking are a faster velocity distribution acquisition for a given angular and energy resolution, or higher angular and energy resolution for a given acquisition rate. It is demonstrated by simulation that such beam tracking strategies can be very effective while limiting the risk of losing the beam. They can be implemented fairly easily with present-day on-board processing resources.

scholarly journals Beam tracking strategies for fast acquisition of solar wind velocity distribution functions with high energy and angular resolutions

2018 ◽  
Vol 36 (5) ◽  
pp. 1285-1302 ◽  
Author(s):  
Johan De Keyser ◽  
Benoit Lavraud ◽  
Lubomir Přech ◽  
Eddy Neefs ◽  
Sophie Berkenbosch ◽  
...  
Keyword(s):  
Solar Wind ◽  
Velocity Distribution ◽  
Energy Resolution ◽  
Three Dimensional ◽  
High Energy ◽  
Distribution Functions ◽  
Acquisition Rate ◽  
Ion Distributions ◽  
Velocity Distribution Functions ◽  
Beam Tracking

Abstract. Space plasma spectrometers have often relied on spacecraft spin to collect three-dimensional particle velocity distributions, which simplifies the instrument design and reduces its resource budgets but limits the velocity distribution acquisition rate. This limitation can in part be overcome by the use of electrostatic deflectors at the entrance of the analyser. By mounting such a spectrometer on a Sun-pointing spacecraft, solar wind ion distributions can be acquired at a much higher rate because the solar wind ion population, which is a cold beam that fills only part of the sky around its mean arrival direction, always remains in view. The present paper demonstrates how the operation of such an instrument can be optimized through the use of beam tracking strategies. The underlying idea is that it is much more efficient to cover only that part of the energy spectrum and those arrival directions where the solar wind beam is expected to be. The advantages of beam tracking are a faster velocity distribution acquisition for a given angular and energy resolution, or higher angular and energy resolution for a given acquisition rate. It is demonstrated by simulation that such beam tracking strategies can be very effective while limiting the risk of losing the beam. They can be implemented fairly easily with present-day on-board processing resources.

Electron and ion velocity distribution functions across one-dimensional tangential discontinuities: particle-in-cell simulations

2021 ◽  
Author(s):  
Gabriel Voitcu ◽  
Marius Echim
Keyword(s):  
Solar Wind ◽  
Velocity Distribution ◽  
Distribution Functions ◽  
Tangential Discontinuity ◽  
Finite Width ◽  
Transition Layers ◽  
One Dimensional ◽  
Particle In Cell ◽  
Velocity Distribution Functions ◽  
Tangential Discontinuities

&lt;div&gt;&lt;span&gt;Tangential discontinuities are finite-width current sheets separating two magnetized plasmas with different macroscopic properties. Such structures have been measured in-situ in the solar wind plasma by various space missions. Also, under certain conditions, the terrestrial magnetopause can be approximated with a tangential discontinuity. Studying the microstructure of tangential discontinuities is fundamentally important to understand the transfer of mass, momentum and energy in space plasmas. The propagation of solar wind discontinuities and their interaction with the terrestrial magnetosphere play a significant role for space weather science. In this paper we use 1d3v electromagnetic particle-in-cell simulations to study the kinetic structure and stability of one-dimensional tangential discontinuities. The simulation setup corresponds to a plasma slab configuration which allows the simultaneous investigation of two discontinuities at the interface between the slab population and the background plasma. The initial discontinuities are infinitesimal and evolve rapidly towards finite-width transition layers. We focus on tangential discontinuities with and without perpendicular velocity shear. Three-dimensional velocity distribution functions are computed in different locations across the discontinuities, at different time instances, for both electrons and ions. We emphasize the space and time evolution of the velocity distribution functions inside the transition layers and discuss their deviation from the initial Maxwellian distributions. The simulated distributions show similar features with the theoretical solutions provided by Vlasov equilibrium models. &lt;/span&gt;&lt;/div&gt;

scholarly journals Dynamic processes and kinetic structure of collisionless reconnection at the dayside magnetopause: comparison between GEOTAIL observations and computer simulations

2003 ◽  
Vol 21 (9) ◽  
pp. 1939-1946 ◽  
Author(s):  
X. H. Deng ◽  
H. Matsumoto ◽  
H. Kojima ◽  
R. R. Anderson ◽  
T. Mukai ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Ion Beams ◽  
Distribution Functions ◽  
Local Magnetic Field ◽  
Diffusion Region ◽  
Ion Diffusion ◽  
Ion Distributions ◽  
Line Region ◽  
Dayside Magnetopause

Abstract. In this paper we report new kinetic features of ions and electrons observed in the vicinity of the reconnection layer on 10 January 1997. This event has a three-dimensional magnetic field topological structure, which is much more complex than the previously suggested two-dimensional magnetic configuration. The ion distributions are non-gyrotropic and electrons show non-Maxwellian distribution functions. Acceleration of multiple ion beams, both parallel and perpendicular to the local magnetic field, have been observed. The perpendicular acceleration of the multiple ion beams can be explained by plasma mixing between the meandering ions accelerated around the ion diffusion region and the cold ions convected directly from the magnetosheath without passing through the X-line region. The parallel acceleration of the multiple ion beams can be understood by the fact that high-velocity ions ejected from the vicinity of the X-line mix with the plasma flowing directly across the boundary. We observed the kinetic effect of the separation of the electron and ion edges due to the time-of-flight effect. It is stressed that kinetic processes are the key to understanding these new observations that cannot be adequately explained by magnetohydrodynamic (MHD) models.Key words. Space plasma physics (magnetic reconnection; charged particle motion and acceleration) – Magnetospheric physics (magnetopause, cusp, and boundary layers)

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