scholarly journals Bursty magnetic reconnection at the Earth's magnetopause triggered by high-speed jets

2021 ◽  
Vol 28 (9) ◽  
pp. 092902 ◽  
Author(s):  
J. Ng ◽  
L.-J. Chen ◽  
Y. A. Omelchenko
Keyword(s):  
Magnetic Reconnection ◽  
High Speed

scholarly journals A case study of dayside reconnection under extremely low solar wind density conditions

2008 ◽  
Vol 26 (11) ◽  
pp. 3571-3583
Author(s):  
R. Maggiolo ◽  
J. A. Sauvaud ◽  
I. Dandouras ◽  
E. Luceck ◽  
H. Rème
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
High Speed ◽  
Radial Distance ◽  
Plasma Jets ◽  
Solar Wind Density ◽  
Ion Distribution ◽  
Dayside Magnetopause ◽  
Field Lines

Abstract. From 15 February 2004, 20:00 UT to 18 February 2004, 01:00 UT, the solar wind density dropped to extremely low values (about 0.35 cm−3). On 17 February, between 17:45 UT and 18:10 UT, the CLUSTER spacecraft cross the dayside magnetopause several times at a large radial distance of about 16 RE. During each of these crossings, the spacecraft detect high speed plasma jets in the dayside magnetopause and boundary layer. These observations are made during a period of southward and dawnward Interplanetary Magnetic Field (IMF). The magnetic shear across the local magnetopause is ~90° and the magnetosheath beta is very low (~0.15). We evidence the presence of a magnetic field of a few nT along the magnetopause normal. We also show that the plasma jets, accelerated up to 600 km/s, satisfy the tangential stress balance. These findings strongly suggest that the accelerated jets are due to magnetic reconnection between interplanetary and terrestrial magnetic field lines northward of the satellites. This is confirmed by the analysis of the ion distribution function that exhibits the presence of D shaped distributions and of a reflected ion population as predicted by theory. A quantitative analysis of the reflected ion population reveals that the reconnection process lasts about 30 min in a reconnection site located at a very large distance of several tens RE from the Cluster spacecraft. We also estimate the magnetopause motion and thickness during this event. This paper gives the first experimental study of magnetic reconnection during such rare periods of very low solar wind density. The results are discussed in the frame of magnetospheric response to extremely low solar wind density conditions.

Filamentary Currents in Turbulent Magnetic Reconnection

2020 ◽  
Author(s):  
Meng Zhou ◽  
Xiaohua Deng ◽  
Zhihong Zhong ◽  
Ye Pang
Keyword(s):  
Plasma Physics ◽  
Magnetic Reconnection ◽  
Current Sheet ◽  
Coherent Structures ◽  
High Speed ◽  
Large Scale ◽  
Magnetic Energy ◽  
Normal Direction ◽  
Neutral Sheet ◽  
Current Filaments

<p>Magnetic reconnection and turbulence are the two most important energy conversion phenomena in plasma physics. Magnetic reconnection and turbulence are often intertwined. For example, reconnection occurs in thin current layers formed during cascades of turbulence, while reconnection in large-scale current sheet also evolves into turbulence. How energy is dissipated and how particles are accelerated in turbulent magnetic reconnection are outstanding questions in magnetic reconnection and turbulence. Here we report MMS observations of filamentary currents in turbulent outflows in the Earth's magnetotail. We found sub-ion-scale filamentary currents in high-speed outflows that evolved into turbulent states. The normal direction of these current filaments is mainly along the X<sub>GSM</sub> direction, which is distinct from the neutral sheet. Some filamentary currents were reconnecting, thereby further dissipating the magnetic energy far from the X line. We notice that turbulent reconnection is more efficient in energizing electrons than laminar reconnection. Coherent structures composed of these filaments may be important in accelerating particles during turbulent reconnection.  </p>

A numerical investigation of magnetic reconnection

1996 ◽  
Vol 55 (3) ◽  
pp. 431-448 ◽  
Author(s):  
Craig Anderson ◽  
Ferdinand Jamitzky
Keyword(s):  
Steady State ◽  
Boundary Conditions ◽  
Magnetic Reconnection ◽  
Current Sheet ◽  
High Speed ◽  
Plasma Jets ◽  
Mhd Equations ◽  
Initial Condition ◽  
Reconnection Rate ◽  
Final Steady State

A time-dependent two-dimensional MHD simulation program is used to investigate the magnetic reconnection process with a spatially uniform diffusivity. Various initial conditions are considered and are allowed to evolve until a final steady state is produced. The boundary conditions are carefully handled in order that they be as strict as possible. In the first series of simulations the initial condition is taken to be an analytical solution of the ideal MHD equations given by Biskamp. Dirichlet (fixed) boundary conditions are used, with a small amount of flexibility allowed on the boundary for the stream function in order to prevent any unphysical currents forming. The final steady- state contains a current sheet whose width and length are found to vary as and respectively, and the reconnection rate is found to be independent of the value of Rm, indicative of fast reconnection. Additionally, as Rm, is increased, a region of reversed current and a high-speed jet of plasma are observed to develop along the MHD shock separating the inflow and outflow regions. The second series of simulations uses a slightly different initial condition that allows a faster outflow of plasma from the simulation region. The current sheet width of the final steady state is again found to vary as , and the reconnection rate is again independent of Rm. However, no reversed currents or plasma jetting along the shock are observed, indicating that the plasma jets of previous simulations are due to restrictive outflow conditions, which force the high-speed plasma emerging from the end of the current sheet to divert along the MHD shock. Lastly, the analytical model of Petschek is utilized to provide an initial condition. For this case, however, it is not possible to keep the boundary conditions as strict as before, since both the stream and flux functions have to be allowed to vary slightly in order to deal with the discontinuities of the Petschek model. Although steady-state solutions can be obtained, they are found, owing to the laxness of the boundary conditions, not to exhibit the well-defined structure or small current sheets of the previous results.

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.

Measurement of magnetic reconnection driven by pulse power using ultra high speed laser schlieren technology

2014 ◽  
Vol 26 (9) ◽  
pp. 92006
Author(s):  
李剑 Li Jian ◽  
但加坤 Dan Jiakun ◽  
赵新才 Zhao Xincai ◽  
刘宁文 Liu Ningwen
Keyword(s):  
Magnetic Reconnection ◽  
High Speed ◽  
Pulse Power ◽  
Ultra High Speed

Formation of high-speed electron jets as the evidence for magnetic reconnection in laser-produced plasma

2017 ◽  
Vol 24 (4) ◽  
pp. 041406 ◽  
Author(s):  
Kai Huang ◽  
Can Huang ◽  
Quanli Dong ◽  
Quanming Lu ◽  
San Lu ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
High Speed ◽  
Laser Produced Plasma

Turbulence-driven magnetic reconnection in the magnetosheath downstream of a quasi-parallel shock：a three-dimensional global hybrid simulation

2020 ◽  
Author(s):  
Quanming Lu ◽  
Huanyu Wang ◽  
Xueyi Wang
Keyword(s):  
Magnetic Reconnection ◽  
Electromagnetic Waves ◽  
High Speed ◽  
Three Dimensional ◽  
Hybrid Simulation ◽  
Bow Shock ◽  
Ion Flow ◽  
Current Sheets ◽  
The Earth ◽  
Outflow Region

<p>Satellite observations with high-resolution measurements have demonstrated the existence of intermittent current sheets and occurrence of magnetic reconnection in a quasi-parallel magnetosheath behind the terrestrial bow shock. In this Letter, by performing a three-dimensional (3-D) global hybrid simulation, we investigated the characteristics of the quasi-parallel magnetosheath of the bow shock, which is formed due to the interaction of the solar wind with the earth’s magnetosphere. Current sheets with widths of several ion inertial lengths are found to be produced in the magnetosheath after the upstream large amplitude electromagnetic waves penetrate through the shock and are then compressed in the downstream. Magnetic reconnection consequently occurs in these current sheets, where high-speed ion flow jets are identified in the outflow region. Simultaneously, flux ropes with the extension (along the   direction) of about several earth’s radii are also observed. Our simulation shed new insight on the mechanism for the occurrence of magnetic reconnection in the quasi-parallel shocked magnetosheath.</p>

scholarly journals Impulsive Flare Plasma Energization in the Light of Yohkoh Discoveries

1998 ◽  
Vol 188 ◽  
pp. 211-212
Author(s):  
Yurii M. Voitenko
Keyword(s):  
Theoretical Prediction ◽  
Magnetic Reconnection ◽  
High Speed ◽  
Magnetic Loop ◽  
High Energy ◽  
Flare Plasma ◽  
Reconnection Site ◽  
High Energy Particles ◽  
Impulsive Flare

Flare scenario, based on Yohkoh observations and magnetic reconnection (MR) hypotesis, has been elaborated recently (Tsuneta, 1996; Shibata, 1997). Using theoretical prediction that the fast MR results in a high-speed outflows from reconnection site, the reconnection downflow has been supposed to collide with the top of underlying magnetic loop, producing superhot plasma and high-energy particles.

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