scholarly journals Forced current sheet structure, formation and evolution: application to magnetic reconnection in the magnetosphere

2004 ◽  
Vol 22 (7) ◽  
pp. 2547-2553 ◽  
Author(s):  
V. I. Domrin ◽  
A. P. Kropotkin
Keyword(s):  
Magnetic Reconnection ◽  
Current Sheet ◽  
Particle Interaction ◽  
Nonlinear Process ◽  
Ion Distribution ◽  
Wave Type ◽  
Ion Distributions ◽  
Sheet Structure ◽  
Formation And Evolution ◽  
Nonlinear Kinetic

Abstract. By means of a simulation model, the earlier predicted nonlinear kinetic structure, a Forced Kinetic Current Sheet (FKCS), with extremely anisotropic ion distributions, is shown to appear as a result of a fast nonlinear process of transition from a previously existing equilibrium. This occurs under triggering action of a weak MHD disturbance that is applied at the boundary of the simulation box. In the FKCS, current is carried by initially cold ions which are brought into the CS by convection from both sides, and accelerated inside the CS. The process then appears to be spontaneously self-sustained, as a MHD disturbance of a rarefaction wave type propagates over the background plasma outside the CS. Comparable to the Alfvénic discontinuity in MHD, transformation of electromagnetic energy into the energy of plasma flows occurs at the FKCS. But unlike the MHD case, ``free" energy is produced here: dissipation should occur later, through particle interaction with turbulent waves generated by unstable ion distribution being formed by the FKCS action. In this way, an effect of magnetic field ``annihilation" appears, required for fast magnetic reconnection. Application of the theory to observations at the magnetopause and in the magnetotail is considered.

scholarly journals Revisiting the theory of the evolution of pick-up ion distributions: magnetic or adiabatic cooling?

2007 ◽  
Vol 25 (12) ◽  
pp. 2649-2659 ◽  
Author(s):  
H. J. Fahr
Keyword(s):  
Solar Wind ◽  
Particle Interaction ◽  
Distribution Functions ◽  
Particle Interactions ◽  
Ion Distribution ◽  
Ion Distributions ◽  
Magnetic Cooling ◽  
Adiabatic Cooling ◽  
Diffusive Acceleration ◽  
Nonlinear Energy

Abstract. We study the phasespace behaviour of heliospheric pick-up ions after the time of their injection as newly created ions into the solar wind bulk flow from either charge exchange or photoionization of interplanetary neutral atoms. As interaction with the ambient MHD wave fields we allow for rapid pitch angle diffusion, but for the beginning of this paper we shall neglect the effect of quasilinear or nonlinear energy diffusion (Fermi-2 acceleration) induced by counterflowing ambient waves. In the up-to-now literature connected with the convection of pick-up ions by the solar wind only adiabatic cooling of these ions is considered which in the solar wind frame takes care of filling the gap between the injection energy and energies of the thermal bulk of solar wind ions. Here we reinvestigate the basics of the theory behind this assumption of adiabatic pick-up ion reactions and correlated predictions derived from it. We then compare it with the new assumption of a pure magnetic cooling of pick-up ions simply resulting from their being convected in an interplanetary magnetic field which decreases in magnitude with increase of solar distance. We compare the results for pick-up ion distribution functions derived along both ways and can point out essential differences of observational and diagnostic relevance. Furthermore we then include stochastic acceleration processes by wave-particle interactions. As we can show, magnetic cooling in conjunction with diffusive acceleration by wave-particle interaction allows for an unbroken power law with the unique power index γ=−5 beginning from lowest velocities up to highest energy particles of about 100 KeV which just marginally can be in resonance with magnetoacoustic turbulences. Consequences for the resulting pick-up ion pressures are also analysed.

scholarly journals Current sheet structure and kinetic properties of plasma flows during a near-Earth magnetic reconnection under the presence of a guide field

2013 ◽  
Vol 118 (6) ◽  
pp. 3265-3287 ◽  
Author(s):  
E. E. Grigorenko ◽  
H. V. Malova ◽  
A. V. Artemyev ◽  
O. V. Mingalev ◽  
E. A. Kronberg ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Current Sheet ◽  
Kinetic Properties ◽  
Plasma Flows ◽  
Guide Field ◽  
Sheet Structure

scholarly journals Full particle-in-cell simulations of kinetic equilibria and the role of the initial current sheet on steady asymmetric magnetic reconnection

2016 ◽  
Vol 82 (3) ◽  
Author(s):  
J. Dargent ◽  
N. Aunai ◽  
G. Belmont ◽  
N. Dorville ◽  
B. Lavraud ◽  
...  
Keyword(s):  
Distribution Function ◽  
Magnetic Reconnection ◽  
Current Sheet ◽  
Initial Conditions ◽  
Electron Flow ◽  
Electron Distribution Function ◽  
Ion Distribution ◽  
Initial Current ◽  
Particle In Cell ◽  
Kinetic Equilibrium

Tangential current sheets are ubiquitous in space plasmas and yet hard to describe with a kinetic equilibrium. In this paper, we use a semi-analytical model, the BAS model, which provides a steady ion distribution function for a tangential asymmetric current sheet and we prove that an ion kinetic equilibrium produced by this model remains steady in a fully kinetic particle-in-cell simulation even if the electron distribution function does not satisfy the time independent Vlasov equation. We then apply this equilibrium to look at the dependence of magnetic reconnection simulations on their initial conditions. We show that, as the current sheet evolves from a symmetric to an asymmetric upstream plasma, the reconnection rate is impacted and the X line and the electron flow stagnation point separate from one another and start to drift. For the simulated systems, we investigate the overall evolution of the reconnection process via the classical signatures discussed in the literature and searched in the Magnetospheric MultiScale data. We show that they seem robust and do not depend on the specific details of the internal structure of the initial current sheet.

scholarly journals Observations of Turbulent Magnetic Reconnection within a Solar Current Sheet

2018 ◽  
Vol 866 (1) ◽  
pp. 64 ◽  
Author(s):  
X. Cheng ◽  
Y. Li ◽  
L. F. Wan ◽  
M. D. Ding ◽  
P. F. Chen ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Current Sheet

scholarly journals Numerical study of the reconnection process between magnetic cloud and heliospheric current sheet

2018 ◽  
Vol 619 ◽  
pp. A82
Author(s):  
Man Zhang ◽  
Yu Fen Zhou ◽  
Xue Shang Feng ◽  
Bo Li ◽  
Ming Xiong
Keyword(s):  
Magnetic Reconnection ◽  
Current Sheet ◽  
Dynamic Process ◽  
Large Scale ◽  
Magnetic Cloud ◽  
Numerical Study ◽  
Three Dimensional ◽  
Heliospheric Current Sheet ◽  
Reconnection Process ◽  
Magnetic Filed

In this paper, we have used a three-dimensional numerical magnetohydrodynamics model to study the reconnection process between magnetic cloud and heliospheric current sheet. Within a steady-state heliospheric model that gives a reasonable large-scale structure of the solar wind near solar minimum, we injected a spherical plasmoid to mimic a magnetic cloud. When the magnetic cloud moves to the heliospheric current sheet, the dynamic process causes the current sheet to become gradually thinner and the magnetic reconnection begin. The numerical simulation can reproduce the basic characteristics of the magnetic reconnection, such as the correlated/anticorrelated signatures in V and B passing a reconnection exhaust. Depending on the initial magnetic helicity of the cloud, magnetic reconnection occurs at points along the boundary of the two systems where antiparallel field lines are forced together. We find the magnetic filed and velocity in the MC have a effect on the reconnection rate, and the magnitude of velocity can also effect the beginning time of reconnection. These results are helpful in understanding and identifying the dynamic process occurring between the magnetic cloud and the heliospheric current sheet.

Statistics on Jupiter's Current Sheet with Juno Data: Geometry, Magnetic Fields and Energetic Particles

2021 ◽  
Author(s):  
Zhi-Yang Liu ◽  
Qiu-Gang Zong ◽  
Michel Blanc
Keyword(s):  
Magnetic Fields ◽  
Current Sheet ◽  
Power Law ◽  
Heavy Ions ◽  
Particle Interaction ◽  
The Other ◽  
Gaussian Functions ◽  
Fixed Energy ◽  
Thin Current Sheet ◽  
A Current

<p>Jupiter's magnetosphere contains a current sheet of huge size near its equator. The current sheet not only mediates the global mass and energy cycles of Jupiter's magnetosphere, but also provides an occurring place for many localized dynamic processes, such as reconnection and wave-particle interaction. To correctly evaluate its role in these processes, a statistical description of the current sheet is required. To this end, here we conduct statistics on Jupiter's current sheet, with four-year Juno data recorded in the 20-100 Jupiter radii, post-midnight magnetosphere. The results suggest a thin current sheet whose thickness is comparable with the gyro-radius of dominant ions. Magnetic fields in the current sheet decrease in power-law with increasing radial distances. At fixed energy, the flux of electrons and protons increases with decreasing radial distances. On the other hand, at fixed radial distances, the flux decreases in power-law with increasing energy. The flux also varies with the distances to the current sheet center. The corresponding relationship can be well described by Gaussian functions peaking at the current sheet center. In addition, the statistics show the flux of oxygen- and sulfur-group ions is comparable with the flux of protons at the same energy and radial distances, indicating the non-negligible effects of heavy ions on current sheet dynamics. From these results, a statistical model of Jupiter's current sheet is constructed, which provides us with a start point of understanding the dynamics of the whole Jupiter's magnetosphere.</p>

scholarly journals Magnetically Driven Motions in Solar Corona

1980 ◽  
Vol 91 ◽  
pp. 487-489 ◽  
Author(s):  
B. V. Somov ◽  
S. I. Syrovatskii
Keyword(s):  
Magnetic Field ◽  
Solar Corona ◽  
Magnetic Reconnection ◽  
Current Sheet ◽  
Magnetic Dipole ◽  
Plasma Flow ◽  
Strong Field ◽  
Plasma Velocity ◽  
Rapid Process

Solution of the nonlinear MHD problem of plasma flow in an increasing dipolar magnetic field is obtained in the approximation of a strong field. The distributions of plasma velocity, displacement, and density are calculated. The situation when the magnetic dipole is ‘increased’ by rapid process of magnetic reconnection or current sheet rupture is illustrated. Possible applications are discussed in connection with plasma ejections from chromosphere in corona.

scholarly journals Investigation of a Collisional Radiative Model for Laser-Produced Plasmas

Atoms ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 52
Author(s):  
Nicholas L. Wong ◽  
Fergal O’Reilly ◽  
Emma Sokell
Keyword(s):  
Radiative Recombination ◽  
Rate Coefficients ◽  
Ion Distribution ◽  
Ion Distributions ◽  
Nist Database ◽  
Collisional Radiative Model ◽  
Radiative Model ◽  
Collisional Ionization ◽  
Three Body ◽  
Body Recombination

Plasmas of a variety of types can be described by the collisional radiative (CR) model developed by Colombant and Tonan. From the CR model, the ion distribution of a plasma at a given electron temperature and density can be found. This information is useful for further simulations, and due to this, the employment of a suitable CR model is important. Specifically, ionization bottlenecks, where there are enhanced populations of certain charge states, can be seen in these ion distributions, which in some applications are important in maintaining large amounts of a specific ion. The present work was done by implementing an accepted CR model, proposed by Colombant and Tonon, in Python and investigating the effects of variations in the ionization energy and outermost electron subshell occupancy term on the positions of ionization bottlenecks. Laser Produced Plasmas created using a Nd:YAG laser with an electron density of ∼ne = 1021 cm−3 were the focus of this work. Plots of the collisional ionization, radiative recombination, and three-body recombination rate coefficients as well as the ion distribution and peak fractional ion population for various elements were examined. From these results, it is evident that using ionization energies from the NIST database and removing the orbital occupancy term in the CR model produced results with ionization bottlenecks in expected locations.

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