Revisiting electron diffusion region in Magnetic Reconnection Experiments (MRX) via fully kinetic cylindrical particle-in-cell simulation.

Magnetic reconnection is a ubiquitous plasma process that converts magnetic energy into particle energy in plasma environments ranging from laboratory to astrophysics. Its essential engine is the kinetic ion and electron diffusion regions (IDR and EDR), where ions and electrons, respectively, decouple from magnetic field lines. Over the past decade, in-situ diagnostics on laboratory experiments, including the Magnetic Reconnection Experiment (MRX), have provided detailed measurements of this kinetic‐scale physics. Fully kinetic Cartesian particle-in-cell (PIC) simulations have reproduced many MRX observations and clarified key underlying mechanisms, such as scaling of those kinetic structures. A persistent discrepancy remains, however: PIC models underestimate the EDR thickness in the unit of electron kinetic scales by a factor of 3–5, even when realistic mass ratios, boundary conditions, collisionality, and three-dimensional effects are included. To revisit this mismatch, we have conducted Cylindrical PIC simulations better tailored to the actual MRX geometry and driving conditions. By systematically varying the computational free parameters that make kinetic runs tractable, such as mass ratio, initial seed velocity, initial background density profile, etc., their individual impacts on resulting EDR structure are quantified.