The Inertia‐Based Model for Reconstruction of the Electron Diffusion Region

Abstract

Fast magnetic reconnection is an explosive plasma process, bringing the topological reconfiguration of magnetic fields, plasma heating, and acceleration in laboratory and space plasmas (e.g., Gonzalez & Parker, 2016;Yamada et al., 2010). In general, this is a time-dependent multi-scale three-dimensional process (e.g., Bhattacharjee, 2004;Dorfman et al., 2013;Frank, 1999;Xiao et al., 2006), but sometimes reconnection may demonstrate a symmetric configuration and be quasi-stationary. Particularly, at the day side of the Earth's magnetopause, quasi-stationary reconnection has been detected in-situ on several occasions (e.g., Gosling et al., 1982;Phan et al., 2004;Retinò et al., 2005) as well as anti-parallel reconnection (Cassak & Fuselier, 2016, and references therein). The latter is more common in the Earth's magnetotail (Paschmann et al., 2013). It is also important that in many cases reconnection can be studied analytically in the frame of two-dimensional models for the considerable length of the reconnection X-line. Configurations with short X-lines demonstrate spreading in the X-line direction (see, e.g., Li et al., 2020, and references therein) in course of time. At last, both at the dayside magnetopause and in the magnetotail (e.g., Cassak &

Reconstruction of the Electron Diffusion Region With Inertia and Compressibility Effects

“…This is because these assumptions are roughly satisfied in the region of antiparallel reconnection (Figures A1a and A1c in Appendix A) and allow for a sufficiently good reconstruction of the transverse magnetic field (Hasegawa et al, , 2019Korovinskiy et al, 2020Korovinskiy et al, , 2021Sonnerup et al, 2016). The functional…”

“…Summary and discussion are given in Section 6 , and Appendix A provides some discussions on the assumptions made in the present study and in Korovinskiy et al. ( 2021 ), along with key differences between the two studies.…”

“…Some of the above assumptions made in the original EMHD reconstruction have been relaxed in a recent work by Korovinskiy et al. ( 2021 ), allowing for reconstruction with electron inertia and guide‐field effects taken into account, but with an additional assumption on the electron velocity field. However, their model still assumes electron incompressibility (uniform electron density, i.e., ), and we find their assumption on the velocity field, or equivalently, on the magnetic field component along the direction of negligible gradient ( ) to be not well satisfied in and around the EDR (Appendix A ).…”

“…This means that it cannot be applied to most of magnetopause reconnection events in which both the guide magnetic field (field component along the X-line direction) and density jump across the current sheet are often significant . Some of the above assumptions made in the original EMHD reconstruction have been relaxed in a recent work by Korovinskiy et al (2021), allowing for reconstruction with electron inertia and guide-field effects taken into account, but with an additional assumption on the electron velocity field. However, their model still assumes electron incompressibility (uniform electron density, i.e.,  const.…”

“…Section 5 presents first results of the new reconstruction applied to the EDR of magnetotail reconnection observed by MMS on July 11, 2017, previously analyzed by Hasegawa et al (2019) and Torbert et al (2018). Summary and discussion are given in Section 6, and Appendix A provides some discussions on the assumptions made in the present study and in Korovinskiy et al (2021), along with key differences between the two studies.…”