scholarly journals Role of Z-pinches in magnetic reconnection in space plasmas

2014 ◽  
Vol 81 (1) ◽  
Author(s):  
Vyacheslav Olshevsky ◽  
Giovanni Lapenta ◽  
Stefano Markidis ◽  
Andrey Divin
Keyword(s):  
Magnetic Reconnection ◽  
Magnetic Energy ◽  
Large Fraction ◽  
Three Dimensional ◽  
Space Plasmas ◽  
Particle In Cell ◽  
Cell Simulation ◽  
Field Lines ◽  
Three Dimensional Configuration

A widely accepted scenario of magnetic reconnection in collisionless space plasmas is the breakage of magnetic field lines in X-points. In laboratory, reconnection is commonly studied in pinches, current channels embedded into twisted magnetic fields. No model of magnetic reconnection in space plasmas considers both null-points and pinches as peers. We have performed a particle-in-cell simulation of magnetic reconnection in a three-dimensional configuration where null-points are present initially, and Z-pinches are formed during the simulation along the lines of spiral null-points. The non-spiral null-points are more stable than spiral ones, and no substantial energy dissipation is associated with them. On the contrary, turbulent magnetic reconnection in the pinches causes the magnetic energy to decay at a rate of ~1.5% per ion gyro period. Dissipation in similar structures is a likely scenario in space plasmas with large fraction of spiral null-points.

scholarly journals Studying particle acceleration from driven magnetic reconnection at the termination shock of a relativistic striped wind using particle-in-cell simulations

2020 ◽  
Vol 235 ◽  
pp. 07003
Author(s):  
Yingchao Lu ◽  
Fan Guo ◽  
Patrick Kilian ◽  
Hui Li ◽  
Chengkun Huang ◽  
...  
Keyword(s):  
Particle Acceleration ◽  
Magnetic Reconnection ◽  
Magnetic Energy ◽  
Maximum Energy ◽  
Termination Shock ◽  
Particle In Cell ◽  
Poynting Flux ◽  
Electrons And Positrons ◽  
Particle Kinetic Energy ◽  
Fermi Type

A rotating pulsar creates a surrounding pulsar wind nebula (PWN) by steadily releasing an energetic wind into the interior of the expanding shockwave of supernova remnant or interstellar medium. At the termination shock of a PWN, the Poynting-flux- dominated relativistic striped wind is compressed. Magnetic reconnection is driven by the compression and converts magnetic energy into particle kinetic energy and accelerating particles to high energies. We carrying out particle-in-cell (PIC) simulations to study the shock structure as well as the energy conversion and particle acceleration mechanism. By analyzing particle trajectories, we find that many particles are accelerated by Fermi-type mechanism. The maximum energy for electrons and positrons can reach hundreds of TeV.

scholarly journals Phase space structures generated by absorbing obstacles in streaming plasmas

2005 ◽  
Vol 23 (3) ◽  
pp. 853-865 ◽  
Author(s):  
P. Guio ◽  
H. L. Pécseli
Keyword(s):  
Phase Space ◽  
Collisionless Plasma ◽  
Flow Characteristics ◽  
Plasma Potential ◽  
Velocity Shear ◽  
Space Structures ◽  
Space Plasmas ◽  
Physical Parameters ◽  
Particle In Cell ◽  
Cell Simulation

Abstract. The dynamic behavior of a collisionless plasma flowing around an obstacle is investigated by numerical methods. In the present studies, the obstacle is formed by an absorbing cylinder, and a 2-D electrostatic particle-in-cell simulation is used to study the flow characteristics, with extensions to a fully 3-D generalization of the problem demonstrated as well. The formation of irregular filamented density depletions, oblique to the flow, is observed. The structures form behind the obstacle, in a region with a strong velocity shear, but also other instability mechanisms can be identified. The dynamics of these structures is highly dependent on the physical parameters of the plasma, and they can either be quasi-stationary or undergo a dynamic evolution. The structures are found to be associated with phase-space vortices, observed especially in the phase space spanned by the velocity direction perpendicular to the flow and the spatial coordinate in the same direction. The bias of the obstacle with respect to the plasma potential is found to be an important parameter for the dynamics of the structures, but seemingly not for their formation as such. The results can be of interest in the interpretation of structures in space plasmas as observed by instrumented spacecrafts.

scholarly journals 2D and 3D turbulent magnetic reconnection

2009 ◽  
Vol 5 (H15) ◽  
pp. 434-435
Author(s):  
A. Lazarian ◽  
G. Kowal ◽  
E. Vishniac ◽  
K. Kulpa-Dubel ◽  
K. Otmianowska-Mazur
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Large Scale ◽  
Gamma Ray ◽  
Three Dimensional ◽  
Turnover Time ◽  
Turbulent Fluid ◽  
Astrophysical Objects ◽  
Field Lines ◽  
The Magnetic Field

AbstractA magnetic field embedded in a perfectly conducting fluid preserves its topology for all times. Although ionized astrophysical objects, like stars and galactic disks, are almost perfectly conducting, they show indications of changes in topology, magnetic reconnection, on dynamical time scales. Reconnection can be observed directly in the solar corona, but can also be inferred from the existence of large scale dynamo activity inside stellar interiors. Solar flares and gamma ray busts are usually associated with magnetic reconnection. Previous work has concentrated on showing how reconnection can be rapid in plasmas with very small collision rates. Here we present numerical evidence, based on three dimensional simulations, that reconnection in a turbulent fluid occurs at a speed comparable to the rms velocity of the turbulence, regardless of the value of the resistivity. In particular, this is true for turbulent pressures much weaker than the magnetic field pressure so that the magnetic field lines are only slightly bent by the turbulence. These results are consistent with the proposal by Lazarian & Vishniac (1999) that reconnection is controlled by the stochastic diffusion of magnetic field lines, which produces a broad outflow of plasma from the reconnection zone. This work implies that reconnection in a turbulent fluid typically takes place in approximately a single eddy turnover time, with broad implications for dynamo activity and particle acceleration throughout the universe. In contrast, the reconnection in 2D configurations in the presence of turbulence depends on resistivity, i.e. is slow.

magnetic reconnection onset from electron phase to ion phase

2020 ◽  
Author(s):  
Rongsheng Wang
Keyword(s):  
Magnetic Reconnection ◽  
Particle In Cell ◽  
Cell Simulation ◽  
Two Phases

<p>It is still unresolved that how magnetic reconnection is triggered in the collisionless environment. In this talk, we will present that the reconnection onset consists of two phases: the electron phase and ion phase. In the electron phase, the electrons are significantly energized and super-alfvenic electron jets are created while the ion bulk flows haven't been formed and the ions haven't been heated. Later on, the ion jets are produced together with the electron jets in the ion phase. The main reason for such two phases is discussed. A particle-in-cell simulation was performed to realize these two phases during reconnection onset. </p><p> </p>

scholarly journals Three-dimensional particle-in-cell simulation study of a relativistic magnetron

1999 ◽  
Vol 6 (2) ◽  
pp. 603-613 ◽  
Author(s):  
R. W. Lemke ◽  
T. C. Genoni ◽  
T. A. Spencer
Keyword(s):  
Simulation Study ◽  
Three Dimensional ◽  
Particle In Cell ◽  
Relativistic Magnetron ◽  
Cell Simulation

scholarly journals Thrust Evaluation of Small-Scale Magnetic Sail Spacecraft by Three-Dimensional Particle-in-Cell Simulation

2014 ◽  
Vol 30 (1) ◽  
pp. 186-196 ◽  
Author(s):  
Yasumasa Ashida ◽  
Hiroshi Yamakawa ◽  
Ikkoh Funaki ◽  
Hideyuki Usui ◽  
Yoshihiro Kajimura ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Small Scale ◽  
Particle In Cell ◽  
Cell Simulation

scholarly journals Three-dimensional magnetic reconnection and its application to solar flares

2017 ◽  
Vol 83 (1) ◽  
Author(s):  
Miho Janvier
Keyword(s):  
Kinetic Energy ◽  
Numerical Simulations ◽  
Magnetic Reconnection ◽  
Solar Flares ◽  
Magnetic Energy ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Current Layer ◽  
Solar Observations ◽  
The Universe

Solar flares are powerful radiations occurring in the Sun’s atmosphere. They are powered by magnetic reconnection, a phenomenon that can convert magnetic energy into other forms of energy such as heat and kinetic energy, and which is believed to be ubiquitous in the universe. With the ever increasing spatial and temporal resolutions of solar observations, as well as numerical simulations benefiting from increasing computer power, we can now probe into the nature and the characteristics of magnetic reconnection in three dimensions to better understand the phenomenon’s consequences during eruptive flares in our star’s atmosphere. We review in the following the efforts made on different fronts to approach the problem of magnetic reconnection. In particular, we will see how understanding the magnetic topology in three dimensions helps in locating the most probable regions for reconnection to occur, how the current layer evolves in three dimensions and how reconnection leads to the formation of flux ropes, plasmoids and flaring loops.

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