2024/11/20 by Fan, Cheng-Yu, Shan Wang, Xu‐Zhi Zhou +12
Chemistry · #Mass Spectrometry Techniques and Applications
paper · pdf · doi:10.48550/arxiv.2411.13352
The recently discovered electron-only reconnection has drawn great interests due to abnormal features like lack of ion outflows and high reconnection rates. Using particle-in-cell simulations, we investigate their physical mechanisms. The reconnection rate, when normalized by ion parameters (Ri), may appear anomalously high, whereas that normalized by electron parameters (Re) remains ~0.1. We propose that the essence of high Ri is insufficient field line bending outside the electron diffusion region, indicating an incomplete development of the ion diffusion region. It may result from bursty reconnection in thin current sheets, or small system sizes. The ion outflow diminishes at high βi when the gyroradius (ρi) exceeds the system size. Low-velocity ions still experience notable acceleration from Hall fields. However, a local distribution includes many high-velocity ions that experience random accelerations from different electric fields across ρi, resulting in near-zero bulk velocities. Our study helps understand reconnection structures and the underlying physics for transitions between different regimes.