Laboratory and PIC simulations of collisionless interaction between expanding space plasma clouds and magnetic field with and without ionised background

2006 ◽  
Vol 133 ◽  
pp. 1025-1030
Author(s):  
D. Mourenas ◽  
F. Simonet ◽  
Yu. P. Zakharov ◽  
A. G. Ponomarenko ◽  
V. M. Antonov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Space Plasma

Helical Magnetic Cavities: Kinetic Model and Comparison with MMS Observations

2021 ◽  
Author(s):  
Jinghuan Li ◽  
Xuzhi Zhou ◽  
Fan Yang ◽  
Anton V. Artemyev ◽  
Qiugang Zong
Keyword(s):  
Magnetic Field ◽  
Kinetic Model ◽  
Pitch Angle ◽  
Maxwell Equations ◽  
Equilibrium Solution ◽  
Space Plasma ◽  
Azimuthal Magnetic Field ◽  
Particle Distributions ◽  
Multi Scale ◽  
Self Consistent

<p>Magnetic cavities are sudden depressions of magnetic field strength widely observed in the space plasma environments, which are often accompanied by plasma density and pressure enhancement. To describe these cavities, a self-consistent kinetic model has been proposed as an equilibrium solution to the Vlasov-Maxwell equations. However, observations from the Magnetospheric Multi-Scale (MMS) constellation have shown the existence of helical magnetic cavities characterized by the presence of azimuthal magnetic field, which could not be reconstructed by the aforementioned model. Here, we take into account another invariant of motion, the canonical axial momentum, to construct the particle distributions and accordingly modify the equilibrium model. The reconstructed magnetic cavity shows excellent agreement with the MMS1 observations not only in the electromagnetic field and plasma moment profiles but also in electron pitch-angle distributions. With the same set of parameters, the model also predicts signatures of the neighboring MMS3 spacecraft, matching its observations satisfactorily.</p>

scholarly journals Disturbance of plasma environment in the vicinity of the Astrid-2 microsatellite

2001 ◽  
Vol 19 (6) ◽  
pp. 655-666 ◽  
Author(s):  
N. Ivchenko ◽  
L. Facciolo ◽  
P. A. Lindqvist ◽  
P. Kekkonen ◽  
B. Holback
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Space Plasma ◽  
Plasma Potential ◽  
Space Plasma Physics ◽  
Plasma Environment ◽  
Density Enhancement ◽  
Instruments And Techniques ◽  
Field Lines ◽  
Plasma Depletion

Abstract. The presence of a satellite disturbs the ambient plasma. The charging of the spacecraft creates a sheath around it, and the motion of the satellite creates a wake disturbance. This modification of the plasma environment introduces difficulties in measuring electric fields and plasma densities using the probe technique. We present a study of the structure of the sheath and wake around the Astrid-2 microsatellite, as observed by the probes of the EMMA and LINDA instruments. Measurements with biased LINDA probes, as well as current sweeps on the EMMA probes, show a density enhancement upstream of the satellite and a plasma depletion behind the satellite. The electric field probes detect disturbances in the plasma potential on magnetic field lines connected to the satellite.Key words. Space plasma physics (spacecraft sheaths, wakes, charging; instruments and techniques)

scholarly journals Magnetospheric plasma boundaries: a test of the frozen-in magnetic field theorem

2005 ◽  
Vol 23 (7) ◽  
pp. 2565-2578 ◽  
Author(s):  
R. Lundin ◽  
M. Yamauchi ◽  
J.-A. Sauvaud ◽  
A. Balogh
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Flux ◽  
Plasma Physics ◽  
Electric Fields ◽  
Measurement Data ◽  
Space Plasma ◽  
Space Plasma Physics ◽  
Macroscopic System ◽  
Ideal Mhd

Abstract. The notion of frozen-in magnetic field originates from H. Alfvén, the result of a work on electromagnetic-hydrodynamic waves published in 1942. After that, the notion of frozen-in magnetic field, or ideal MHD, has become widely used in space plasma physics. The controversy on the applicability of ideal MHD started in the late 1950s and has continued ever since. The applicability of ideal MHD is particularly interesting in regions where solar wind plasma may cross the magnetopause and access the magnetosphere. It is generally assumed that a macroscopic system can be described by ideal MHD provided that the violations of ideal MHD are sufficiently small-sized near magnetic x-points (magnetic reconnection). On the other hand, localized departure from ideal MHD also enables other processes to take place, such that plasma may cross the separatrix and access neighbouring magnetic flux tubes. It is therefore important to be able to quantify from direct measurements ideal MHD, a task that has turned out to be a major challenge. An obvious test is to compare the perpendicular electric field with the plasma drift, i.e. to test if E=–v×B. Yet another aspect is to rule out the existence of parallel (to B) electric fields. These two tests have been subject to extensive research for decades. However, the ultimate test of the "frozen-in" condition, based on measurement data, is yet to be identified. We combine Cluster CIS-data and FGM-data, estimating the change in magnetic flux (δB/δt) and the curl of plasma –v×B(∇×(v×B)), the terms in the "frozen-in equation". Our test suggests that ideal MHD applies in a macroscopic sense in major parts of the outer magnetosphere, for instance, in the external cusp and in the high-latitude magnetosheath. However, we also find significant departures from ideal MHD, as expected on smaller scales, but also on larger scales, near the cusp and in the magnetosphere-boundary layer. We discuss the importance of these findings. Keywords. Magnetospheric physics (Magnetopause, cusp and boundary layers; Solar wind-magnetosphere interactions) – Space plasma physics

scholarly journals The mirror mode: a “superconducting” space plasma analogue

2018 ◽  
Vol 36 (4) ◽  
pp. 1015-1026 ◽  
Author(s):  
Rudolf A. Treumann ◽  
Wolfgang Baumjohann
Keyword(s):  
Magnetic Field ◽  
Correlation Length ◽  
Spatial Scales ◽  
Debye Length ◽  
Low Frequency ◽  
Space Plasma ◽  
Equilibrium Structure ◽  
Critical Magnetic Field ◽  
Anisotropic Pressure ◽  
Mirror Mode

Abstract. We examine the physics of the magnetic mirror mode in its final state of saturation, the thermodynamic equilibrium, to demonstrate that the mirror mode is the analogue of a superconducting effect in a classical anisotropic-pressure space plasma. Two different spatial scales are identified which control the behaviour of its evolution. These are the ion inertial scale λim(τ) based on the excess density Nm(τ) generated in the mirror mode, and the Debye scale λD(τ). The Debye length plays the role of the correlation length in superconductivity. Their dependence on the temperature ratio τ=T‖/T⟂<1 is given, with T⟂ the reference temperature at the critical magnetic field. The mirror-mode equilibrium structure under saturation is determined by the Landau–Ginzburg ratio κD=λim/λD, or κρ=λim/ρ, depending on whether the Debye length or the thermal-ion gyroradius ρ – or possibly also an undefined turbulent correlation length ℓturb – serve as correlation lengths. Since in all space plasmas κD≫1, plasmas with λD as the relevant correlation length always behave like type II superconductors, naturally giving rise to chains of local depletions of the magnetic field of the kind observed in the mirror mode. In this way they would provide the plasma with a short-scale magnetic bubble texture. The problem becomes more subtle when ρ is taken as correlation length. In this case the evolution of mirror modes is more restricted. Their existence as chains or trains of larger-scale mirror bubbles implies that another threshold, VA>υ⟂th, is exceeded. Finally, in case the correlation length ℓturb instead results from low-frequency magnetic/magnetohydrodynamic turbulence, the observation of mirror bubbles and the measurement of their spatial scales sets an upper limit on the turbulent correlation length. This might be important in the study of magnetic turbulence in plasmas.

Drift wave in the presence of a time varying inhomogeneous electric field

1983 ◽  
Vol 61 (7) ◽  
pp. 1099-1105 ◽  
Author(s):  
K. D. Misra ◽  
R. P. Pandey ◽  
M. S. Tiwari
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Space Plasma ◽  
Time Varying ◽  
Inhomogeneous Electric Field ◽  
Drift Wave ◽  
Plane Normal ◽  
Vlasov Equations ◽  
Drift Instability ◽  
The Magnetic Field

The drift instability has been studied in the presence of an inhomogeneous time varying electric field directed perpendicular to the impressed magnetic field in the presence of a magnetic field, and density and temperature gradients, using nonlinear particle trajectories in the Maxwell–Boltzmann–Vlasov equations. The dispersion relation and growth rate have been evaluated for the drift wave propagating obliquely to the magnetic field in a plane normal to a density gradient. The stabilization/destabilization of the drift wave by the inhomogeneous applied electric field has been discussed. The application of these results has been suggested for space plasma.

Thermal effects on ion-acoustic whistlers in the ionosphere in the presence of negative ions

1989 ◽  
Vol 67 (5) ◽  
pp. 457-462
Author(s):  
A. K. Sur
Keyword(s):  
Magnetic Field ◽  
Thermal Effects ◽  
Wave Amplitude ◽  
Negative Ions ◽  
Velocity Distribution Function ◽  
Space Plasma ◽  
Ion Acoustic ◽  
Comparison Of The Results ◽  
The Magnetic Field ◽  
Group Travel

In this paper, the thermal effects in the presence of negative ions are included in the evaluation of the group travel time of an ion-cyclotron whistler from its source to an observer in a satellite. The velocity distribution function and the relative wave amplitude of the magnetic field have been estimated theoretically from the cyclotron damping of the whistlers. Comparison of the results with those of Das et al. and Das and Sur shows that negative ions and thermal effects have important contributions to the propagation of whistlers in the ionosphere. An outline of possible applications is given for the study of space plasma problems.

Observations of Magnetic Field Line Curvature and Its Role in the Space Plasma Turbulence

2020 ◽  
Vol 898 (1) ◽  
pp. L18
Author(s):  
S. Y. Huang ◽  
J. Zhang ◽  
F. Sahraoui ◽  
Z. G. Yuan ◽  
X. H. Deng ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Magnetic Field Line ◽  
Space Plasma ◽  
Plasma Turbulence

scholarly journals Evaluation of bispectrum in the wave number domain based on multi-point measurements

2008 ◽  
Vol 26 (11) ◽  
pp. 3389-3393 ◽  
Author(s):  
Y. Narita ◽  
K.-H. Glassmeier ◽  
P. M. E. Décréau ◽  
T. Hada ◽  
U. Motschmann ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Density ◽  
Space Plasma ◽  
Wave Number ◽  
Wave Coupling

Abstract. We present an estimator of the bispectrum, a measure of three-wave couplings. It is evaluated directly in the wave number domain using a limited number of detectors. The ability of the bispectrum estimator is examined numerically and then it is applied to fluctuations of magnetic field and electron density in the terrestrial foreshock region observed by the four Cluster spacecraft, which indicates the presence of a three-wave coupling in space plasma.

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