Large‐Scale Parallel Electric Field Colocated in an Extended Electron Diffusion Region During the Magnetosheath Magnetic Reconnection

Abstract

A strong electron jet was detected in a broad current sheet with a significant pressure anisotropy • The electron jet was identified as an extended electron diffusion region and large-scale parallel electric field was observed inside it • Parallel electric field generates a potential of 120 V and dominates electron acceleration therein

Generation of a Strong Parallel Electric Field and Embedded Electron Jet in the Exhaust of Moderate Guide Field Reconnection

“…Similar features are observed in the simulation data of Figures 3k-3m, though the firehose condition reaches a peak value of ∼0.7, consistent with expectations for a 2D simulation. MMS observations of an electron jet moderated by the marginal firehose condition have been previously reported by Wang et al (2021), but the pressure anisotropy effects in the present event are stronger, and the firehose condition is more closely approached. Wilder et al (2017) found that the electric field was primarily balanced by the divergence in the electron stress tensor, with some timing offset introduced by crossing a structure of a width smaller than the spacecraft separation, and that temporal processes such as double layers were not responsible.…”

“…We suspect that this mechanism for generating a parallel electric field may be present in other MMS observations, such as those reported by Wang et al. (2021), but further analysis will be necessary to determine if this is the case.…”

“…This type of transition structure is expected to develop for a range of conditions where the electrons are marginally magnetized. We hypothesize, for example, that the strong parallel electric field noted in MMS observations of another extended current sheet during a strongly asymmetric reconnection event (Wang et al, 2021) may have been produced by the same effect.…”

Fine Structures of the Electron Current Sheet in Magnetotail Guide‐Field Reconnection

“…The region where the electron frozen‐in condition is violated is named as the electron diffusion region (EDR). Intense currents primarily carried by electrons are often found in the EDR (Burch et al., 2016; Khotyaintsev et al., 2016; Li et al., 2020; Torbert et al., 2018; Wang, Wang, et al., 2021; Zhou et al., 2019, and reference therein), and such thin electron current sheet has also been taken as a typical feature of EDRs (Fuselier et al., 2017; Webster et al., 2018).…”

Sub‐Structures of the Separatrix Region During Magnetic Reconnection

“…Intense particle heating and high‐velocity jets are usually observed along with reconnection (e.g., S. Y. Huang et al., 2010; S. Y. Huang et al., 2020; Torbert et al., 2018). Observations of reconnection at different environments, like magnetopause (Burch et al., 2016; Deng & Matsumoto, 2001; S. Y. Huang et al., 2021; Mozer et al., 2002; Paschmann et al., 1979; R. Wang et al., 2017; Zhong et al., 2021; Zhou et al., 2017), magnetotail (S. Y. Huang, Fu et al., 2016; S. Y. Huang, Retino et al., 2016; S. Y. Huang, Vaivads et al., 2012; S. Y. Huang, Zhou et al., 2012; S. Y. Huang et al., 2017, 2018; 2022; Jiang et al., 2019; Øieroset et al., 2001; Torbert et al., 2018; R. Wang et al., 2010; Zhou, Deng et al., 2019; Zhou, Man et al., 2019), magnetosheath (e.g., Phan et al., 2018; Retinò et al., 2007; S. Wang et al., 2021), and foreshock (Jiang et al., 2021), have been widely reported.…”