Particle‐In‐Cell Simulations of Electrostatic Solitary Waves in Asymmetric Magnetic Reconnection

Chang, Cong; Huang, Kai; Lu, Quanming; Sang, Longlong; Lu, San; Wang, Rongsheng; Gao, Xinliang; Wang, Shui

doi:10.1029/2021ja029290

Cited by 10 publications

(11 citation statements)

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“…(2015) and Chang et al. (2021), phase space holes are dominant on magnetospheric side of reconnection separatrix in asymmetric magnetic reconnection in agreement with these MMS observations.…”

Section: Discussionsupporting

confidence: 87%

Observations of Electron Vorticity and Phase Space Holes in the Magnetopause Reconnection Separatrix

et al. 2022

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Magnetic reconnection is a physical process that converts magnetic energy into kinetic energy. This process happens throughout the universe where opposing magnetic field lines exist including at the Earth's magnetopause. The plasmas on the two sides of the Earth's dayside magnetopause current sheet are often characterized by a strong asymmetry of the magnetic field, plasma number density and temperature. The gradients of magnetic field and density are known to result in an Earthward displacement of the magnetosheath flow stagnation point relative to the magnetic reconnection X-line, where the in-plane reconnecting magnetic field changes direction (Cassak & Shay, 2007. This pattern is commonly referred to as asymmetric magnetic reconnection (Pritchett & Mozer, 2009).Previous numerical studies have predicted a rotation phenomenon for electrons in the exhaust region close to the separatrix of asymmetric magnetopause reconnection. Pritchett and Mozer (2009) used two-dimensional particle-in-cell (PIC) simulations of asymmetric reconnection in the presence of a moderate guide field (∼50%) and showed that a series of electron vortices form sunward of the magnetospheric separatrix region of a southward reconnection jet. Vorticity is the curl of the velocity vector and is a measure of local rotation of the fluid motion. In the simulation, these kinetic-scale electron vortices are proposed to be a result of the electron Kelvin-Helmholtz instability with a ∼0.3 d i width (4 d e with the ion to electron mass ratio of 200) and ∼1 d i spacing between separate electron vorticity structures. Here, d i = c/ω pi is the ion inertial length and 𝐴𝐴 𝐴𝐴𝑝𝑝𝑝𝑝 = √ 𝑛𝑛𝑝𝑝𝑒𝑒 2 ∕𝑚𝑚𝑝𝑝𝜖𝜖0 is the ion plasma frequency. The simulated electron vortices propagated at a speed of about 0.3v A with 𝐴𝐴 𝐴𝐴𝐴𝐴 = 𝐵𝐵∕ √ 𝜇𝜇0𝑛𝑛𝑖𝑖𝑚𝑚𝑖𝑖 being a local ion Alfvén speed and they were associated with fluctuating dissipation regions and changes in the guide magnetic field magnitude that may impact the reconnection topology and energy dissipation. Fermo et al. (2012) used PIC codes to suggest that electron Kelvin-Helmholtz vorticity formation near the separatrix can fold the magnetic field lines and may seed secondary islands.Observations of electron scale vortices were not feasible before the Magnetospheric Multiscale (MMS) mission because of limited time resolution plasma measurements (Burch et al., 2016). Phan et al. (2016) showed enhanced electron vorticity observed within the reconnection exhaust region and the exhaust boundaries downstream of the X-line using MMS data. Observed reductions in electron vorticity magnitude toward the inflow region indicated that the enhancements in vorticity resulted from the reconnection processes. In a recent study, Hwang

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Section: Discussionsupporting

confidence: 87%

Observations of Electron Vorticity and Phase Space Holes in the Magnetopause Reconnection Separatrix

et al. 2022

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“…At the exhaust region near the reconnection site, the outflow of the plasma kinetic energy flux (Figures 8b and 8e) and the enthalpy flux (Figures 8c and 8f) display an antisymmetric structure. It is worth noting that the electron kinetic energy flux is distributed at the separatrices (Figure 8e), along with a stream of perturbating Poynting flux (Figures 8a and 8d), which is likely to be related to electron holes(Chang et al., 2021; C. Huang et al., 2014; Hutchinson, 2017; Lapenta et al., 2010; Q. M. Lu et al., 2008). At the reconnection front, the asymmetry still holds in the kinetic energy flux and the enthalpy flux (Figures 9c–9f).…”

Section: Resultsmentioning

confidence: 99%

Effects of Guide Field and Background Density and Temperature on Energy Conversion at Magnetic Reconnection Front

Shu

et al. 2022

JGR Space Physics

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As a fundamental energy converting process in space, magnetic reconnection is the key to understanding the coupling between the microscale kinetic process and the large-scale MHD process in the magnetosphere. When magnetic reconnection occurs, the magnetic field undergoes a topological change, and the free energy is released to plasmas (Birn & Priest, 2007;Yamada et al., 2010). Due to its ubiquitous presence, magnetic reconnection is often invoked as a promising source of explosive activities such as solar flares (Masuda et al., 1994), coronal mass ejection (Lin & Forbes, 2000), geomagnetic storms and substorms (Baker et al., 1996;Kepko et al., 2015). Furthermore, reconnection also plays a vital role in laboratory plasma facilities (Yamada et al., 1994).Significant progress has been made in investigating the energy conversion at the reconnection site during magnetic reconnection. Birn and Hesse (2005) have shown that although magnetic reconnection is triggered in the diffusion region, which is merely several ion inertial lengths ( 𝐴𝐴 𝐴𝐴𝑖𝑖 ≡ 𝑐𝑐∕𝜔𝜔𝑝𝑝𝑖𝑖 ) wide, the energy conversion is not localized in the diffusion region. They also found that in contrast to the case in the classical resistive Sweet-Parker model, Joule and ohmic dissipation can be neglected in the overall energy transfer in the collisionless magnetic reconnection. The Poynting flux driven into the reconnection site from the inflow region is partially converted to the bulk kinetic flow and the enthalpy flux of plasmas; the rest part is diverted to the exhaust region, forming the pileup front. Satellite observations and numerical simulations have shown that outflow mainly consists of the Poynting flux and the enthalpy flux; the bulk kinetic flux commonly plays a minor role (Birn & Hesse, 2010;Eastwood et al., 2013). In addition, ion enthalpy flux is larger than the electron enthalpy flux in most cases, indicating that ions intend to gain more energy than electrons during the reconnection (

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“…A 2D PIC model that solves the electromagnetic field and particle motion self‐consistently is employed in this paper. The code has been successfully employed to study magnetic reconnection and plasma waves (Chang et al., 2021; C. Huang et al., 2010; K. Huang et al., 2020; Q. Lu et al., 2010). The simulation is performed on the

x - z

plane.…”

Section: Simulation Modelmentioning

confidence: 99%

Formation of Pancake, Rolling Pin, and Cigar Distributions of Energetic Electrons at the Dipolarization Fronts (DFs) Driven by Magnetic Reconnection: A Two‐Dimensional Particle‐In‐Cell Simulation

Huang

et al. 2021

JGR Space Physics

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Particle‐In‐Cell Simulations of Electrostatic Solitary Waves in Asymmetric Magnetic Reconnection

Abstract: Magnetic reconnection is an important physical process with the topological change of the magnetic field lines and the conversion of magnetic energy into plasma kinetic energy (

Cited by 10 publications

References 50 publications

Observations of Electron Vorticity and Phase Space Holes in the Magnetopause Reconnection Separatrix

Observations of Electron Vorticity and Phase Space Holes in the Magnetopause Reconnection Separatrix

Effects of Guide Field and Background Density and Temperature on Energy Conversion at Magnetic Reconnection Front

Formation of Pancake, Rolling Pin, and Cigar Distributions of Energetic Electrons at the Dipolarization Fronts (DFs) Driven by Magnetic Reconnection: A Two‐Dimensional Particle‐In‐Cell Simulation

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