Electron dynamics near the electron diffusion region with a moderate guild field

We examine the detailed electron dynamics within an electron diffusion region (EDR) with a moderate guide field (normalized guide field ~0.5), as observed by the Magnetospheric Multiscale (MMS) spacecraft at the magnetopause. Due to the presence of a moderate guide field, high-energy electrons (>300 eV) can be scattered, while low-energy electrons (<150 eV) remain magnetized. This energy disparity results in the characteristic electron ‘ring’ distribution in velocity phase space. Additionally, we observe clear energization in the perpendicular direction during this event. We further investigate the electron dynamics of scattering and acceleration using test particle simulations. The results reproduce the energy disparity observed in electron scattering and suggest that the perpendicular energization of electrons is driven by the non-ideal electric field E_M​. Due to the presence of a moderate guide field, this non-ideal electric field E_M​ accelerates electrons through both V⊥⋅E⊥and V∥​⋅E∥​. The energy gained in the parallel direction via V∥​⋅E∥​ can then be transferred to the perpendicular direction through electron scattering. Based on spacecraft observations and test particle simulations, we show that the electron dynamics in reconnection with a moderate guide field are distinct from those in anti-parallel reconnection and strong guide field reconnection. These results enhance our understanding of how electron dynamics transition from anti-parallel to strong guide field reconnection.