Authors: Atit Deuja, Haihong Che

Hall effect generates a global quadrupole Hall magnetic field, which plays a crucial role in facilitating fast magnetic reconnection (MR). Tearing instability often arises in MR due to the increasing magnetic shear during the thinning of the current sheet, triggering multiple fast local spontaneous MRs. A critical question that naturally emerges is how these local spontaneous MRs interact with the global Hall magnetic field and affect the reconnection energy release processes. Using a 2.5D particle-in-cell simulation, we investigate this problem in an MR with a Harris current sheet under the guide field-free condition. Our results show that the global MR evolves through two distinct phases: an initial laminar phase marked by a slow magnetic field dissipation, followed by a phase dominated by spontaneous MRs that significantly accelerate the magnetic energy release by driving multiple local spontaneous MRs. We reveal that the Hall magnetic fields produced by the local spontaneous MRs also exhibit quadrupole structures which reinforce or weaken the global Hall magnetic field locally. The local enhanced Hall field is found to be associated with faster spontaneous MR with a rate up to 0.3 which exceeds the laminar MR rate upper-limit 0.2, suggesting that the Hall field interactions may be able to break the bottleneck of the onset of fast MR.