scholarly journals Collisionless magnetic reconnection: analytical model and PIC simulation comparison

2009 ◽  
Vol 27 (3) ◽  
pp. 905-911 ◽  
Author(s):  
V. Semenov ◽  
D. Korovinskiy ◽  
A. Divin ◽  
N. Erkaev ◽  
H. Biernat
Keyword(s):  
Electric Field ◽  
Magnetic Reconnection ◽  
Analytical Model ◽  
Analytical Study ◽  
Spatial Scales ◽  
Magnetospheric Substorms ◽  
Particle In Cell ◽  
Shafranov Equation ◽  
Cell Simulation ◽  
Particles Trajectories

Abstract. Magnetic reconnection is believed to be responsible for various explosive processes in the space plasma including magnetospheric substorms. The Hall effect is proved to play a key role in the reconnection process. An analytical model of steady-state magnetic reconnection in a collisionless incompressible plasma is developed using the electron Hall MHD approximation. It is shown that the initial complicated system of equations may split into a system of independent equations, and the solution of the problem is based on the Grad-Shafranov equation for the magnetic potential. The results of the analytical study are further compared with a two-dimensional particle-in-cell simulation of reconnection. It is shown that both methods demonstrate a close agreement in the electron current and the magnetic and electric field structures obtained. The spatial scales of the acceleration region in the simulation and the analytical study are of the same order. Such features like particles trajectories and the in-plane electric field structure appear essentially similar in both models.

scholarly journals Adaptation of the de Hoffmann–Teller frame for quasi-perpendicular collisionless shocks

2015 ◽  
Vol 33 (3) ◽  
pp. 345-350 ◽  
Author(s):  
H. Comişel ◽  
Y. Narita ◽  
U. Motschmann
Keyword(s):  
Shock Wave ◽  
Electric Field ◽  
Shock Layer ◽  
Local Magnetic Field ◽  
Sliding Velocity ◽  
Collisionless Shock ◽  
Collisionless Shocks ◽  
Particle In Cell ◽  
Cell Simulation ◽  
High Mach

Abstract. The concept of the de Hoffmann–Teller frame is revisited for a high Mach-number quasi-perpendicular collisionless shock wave. Particle-in-cell simulation shows that the local magnetic field oscillations in the shock layer introduce a residual motional electric field in the de Hoffmann–Teller frame, which is misleading in that one may interpret that electrons were not accelerated but decelerated in the shock layer. We propose the concept of the adaptive de Hoffmann–Teller (AHT) frame in which the residual convective field is canceled by modulating the sliding velocity of the de Hoffmann–Teller frame. The electrostatic potential evaluated by Liouville mapping supports the potential profile obtained by electric field in this adaptive frame, offering a wide variety of applications in shock wave studies.

SIMULATION OF HIGH CURRENT FIELD EMISSION FROM VERTICALLY WELL-ALIGNED METALLIC CARBON NANOTUBES

2004 ◽  
Vol 03 (04n05) ◽  
pp. 677-684 ◽  
Author(s):  
W. S. KOH ◽  
L. K. ANG
Keyword(s):  
Electric Field ◽  
Space Charge ◽  
Field Enhancement ◽  
Smooth Transition ◽  
High Current ◽  
Simulation Code ◽  
Particle In Cell ◽  
Current Regime ◽  
Wide Range ◽  
Cell Simulation

We have studied the intense electron beams emitted from multiple metallic, vertical and well-aligned Carbon Nanotube (CNT) field emitters. A two-dimensional (2D) particle-in-cell simulation code MAGIC2D is used to obtain the I–V characteristics near to the apex of the emitters' surface for a given applied electric field and field enhancement factor over a wide range of parameters. The effects of electron space charge and electric field shielding from neighboring emitters are compared in low current and high current regimes. It is found that the electron space charge is dominant in high current regime, where the Fowler–Nordheim (FN) law becomes the 2D Child–Langmuir (CL) law. The emitter spacing, number of emitters, and emitter's uniformity are also particularly studied, and they are more critical in low current regime. Smooth transition from the FN law to CL law is demonstrated.

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 The double layers in the plasma sheet boundary layer during magnetic reconnection

2014 ◽  
Vol 1 (2) ◽  
pp. 1657-1671
Author(s):  
J. Guo ◽  
B. Yu
Keyword(s):  
Boundary Layer ◽  
Magnetic Reconnection ◽  
Plasma Sheet ◽  
Double Layers ◽  
Plasma Sheet Boundary Layer ◽  
Bipolar Structure ◽  
Particle In Cell ◽  
Cell Simulation ◽  
Simulation Results ◽  
Observation Results

Abstract. We studied the evolutions of double layers which appear after the magnetic reconnection through two-dimensional electromagnetic particle-in-cell simulation. The simulation results show that the double layers are formed in the plasma sheet boundary layer after magnetic reconnection. At first, the double layers which have unipolar structures are formed. And then the double layers turn into bipolar structures, which will couple with another new weak bipolar structure. Thus a new double layer or tripolar structure comes into being. The double layers found in our work are about several ten Debye lengths, which accords with the observation results. It is suggested that the electron beam formed during the magnetic reconnection is responsible for the production of the double layers.

scholarly journals Effects on magnetic reconnection of a density asymmetry across the current sheet

2008 ◽  
Vol 26 (8) ◽  
pp. 2471-2483 ◽  
Author(s):  
K. G. Tanaka ◽  
A. Retinò ◽  
Y. Asano ◽  
M. Fujimoto ◽  
I. Shinohara ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Magnetic Reconnection ◽  
Current Sheet ◽  
Three Dimensional ◽  
Flow Region ◽  
Electron Acceleration ◽  
Particle In Cell ◽  
Line Structure ◽  
Simulation Results

Abstract. The magnetopause (MP) reconnection is characterized by a density asymmetry across the current sheet. The asymmetry is expected to produce characteristic features in the reconnection layer. Here we present a comparison between the Cluster MP crossing reported by Retinò et al. (2006) and virtual observations in two-dimensional particle-in-cell simulation results. The simulation, which includes the density asymmetry but has zero guide field in the initial condition, has reproduced well the observed features as follows: (1) The prominent density dip region is detected at the separatrix region (SR) on the magnetospheric (MSP) side of the MP. (2) The intense electric field normal to the MP is pointing to the center of the MP at the location where the density dip is detected. (3) The ion bulk outflow due to the magnetic reconnection is seen to be biased towards the MSP side. (4) The out-of-plane magnetic field (the Hall magnetic field) has bipolar rather than quadrupolar structure, the latter of which is seen for a density symmetric case. The simulation also showed rich electron dynamics (formation of field-aligned beams) in the proximity of the separatrices, which was not fully resolved in the observations. Stepping beyond the simulation-observation comparison, we have also analyzed the electron acceleration and the field line structure in the simulation results. It is found that the bipolar Hall magnetic field structure is produced by the substantial drift of the reconnected field lines at the MSP SR due to the enhanced normal electric field. The field-aligned electrons at the same MSP SR are identified as the gun smokes of the electron acceleration in the close proximity of the X-line. We have also analyzed the X-line structure obtained in the simulation to find that the density asymmetry leads to a steep density gradient in the in-flow region, which may lead to a non-stationary behavior of the X-line when three-dimensional freedom is taken into account.

The Evolution of Collisionless Magnetic Reconnection from Electron Scales to Ion Scales

2021 ◽  
Vol 922 (1) ◽  
pp. 51
Author(s):  
Dongkuan Liu ◽  
Kai Huang ◽  
Quanming Lu ◽  
San Lu ◽  
Rongsheng Wang ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Current Sheet ◽  
High Speed ◽  
Two Dimensional ◽  
Ion Outflow ◽  
Particle In Cell ◽  
Electron Kinetics ◽  
Guide Field ◽  
Cell Simulation ◽  
The Magnetic Field

Abstract It is generally accepted that collisionless magnetic reconnection is initiated on electron scales, which is mediated by electron kinetics. In this paper, by performing a two-dimensional particle-in-cell simulation, we investigate the transition of collisionless magnetic reconnection from electron scales to ion scales in a Harris current sheet with and without a guide field. The results show that after magnetic reconnection is triggered on electron scales, the electrons are first accelerated by the reconnection electric field around the X line, and then leave away along the outflow direction. In the Harris current sheet without a guide field, the electron outflow is symmetric and directed away from the X line along the center of the current sheet, while the existence of a guide field will distort the symmetry of the electron outflow. In both cases, the high-speed electron outflow is decelerated due to the existence of the magnetic field B z , then leading to the pileup of B z . With the increase of B z , the ions are accelerated by the Lorentz force in the outflow direction, and an ion outflow at about one Alfvén speed is at last formed. In this way, collisionless magnetic reconnection is transferred from the electron scales to the ion scales.

scholarly journals Magnetic Reconnection in a Quasi‐Parallel Shock: Two‐Dimensional Local Particle‐in‐Cell Simulation

2019 ◽  
Vol 46 (16) ◽  
pp. 9352-9361 ◽  
Author(s):  
N. Bessho ◽  
L.‐J. Chen ◽  
S. Wang ◽  
M. Hesse ◽  
L. B. Wilson
Keyword(s):  
Magnetic Reconnection ◽  
Two Dimensional ◽  
Particle In Cell ◽  
Cell Simulation
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