New Measure of the Dissipation Region in Collisionless Magnetic Reconnection

TLDR

The study proposes a new measure to identify a small‑scale dissipation region in collisionless magnetic reconnection. The measure is defined as a Lorentz‑invariant scalar of field‑to‑plasma energy transfer in the electron rest frame and validated with 2‑D particle‑in‑cell simulations of symmetric and asymmetric reconnection, with and without a guide field. The measure accurately locates the innermost dissipation region around the reconnection site in all tested scenarios and highlights implications for nonideal MHD dissipation.

Abstract

A new measure to identify a small-scale dissipation region in collisionless magnetic reconnection is proposed. The energy transfer from the electromagnetic field to plasmas in the electron's rest frame is formulated as a Lorentz-invariant scalar quantity. The measure is tested by two-dimensional particle-in-cell simulations in typical configurations: symmetric and asymmetric reconnection, with and without the guide field. The innermost region surrounding the reconnection site is accurately located in all cases. We further discuss implications for nonideal MHD dissipation.