Mechanism of Hall Field and Current Transition from EDR Bipolar to IDR Quadrupolar

Determine the mechanism by which the Hall magnetic field and the associated Hall current transition from a bipolar structure in the electron diffusion region (EDR) to a quadrupolar configuration in the ion diffusion region (IDR) during magnetotail magnetic reconnection when the EDR reconnection plane is non-coplanar with the IDR (a knotted EDR).

Background

The paper reports a Magnetospheric Multiscale (MMS) observation of a knotted electron diffusion region (EDR) in Earth’s magnetotail whose reconnection plane is tilted by approximately 38 degrees relative to the ion diffusion region (IDR). Within the IDR, a quadrupolar Hall magnetic field is observed, whereas within the EDR, the Hall magnetic field is bipolar, indicating distinct Hall current systems at ion and electron scales.

This structural decoupling between EDR and IDR implies complex multiscale coupling during reconnection. The authors explicitly highlight that the process by which the Hall magnetic field and currents reorganize from the EDR’s bipolar structure to the IDR’s quadrupolar pattern is not yet resolved, motivating targeted investigation of the transition mechanism under three-dimensional, non-coplanar conditions.