Particle Acceleration and Transport in the Large-scale Current Sheet under an Erupting Magnetic Flux Rope

作者：H. Wu, Yang Guo, Rony Keppens, Chun Xia, Yang Su, Xiangliang Kong, M. D. Ding · 发表于：The Astrophysical Journal · 年份：2025 · DOI：10.3847/1538-4357/adfed4 · 被引用次数：5 · 研究领域：Solar and Space Plasma Dynamics、Ionosphere and magnetosphere dynamics、Geomagnetism and Paleomagnetism Studies

Abstract We investigate the acceleration and transport of electrons in the highly fine-structured current sheet that develops during magnetic flux rope (MFR) eruptions. Our work combines ultraresolved magnetohydrodynamic (MHD) simulations of MFR eruption, with test-particle studies performed using the guiding center approximation. Our grid-adaptive, fully 3D, high-resolution MHD simulations model MFR eruptions that form complex current-sheet topologies, serving as background electromagnetic fields for particle acceleration. Within the current sheet, tearing-mode instabilities give rise to mini flux ropes. Electrons become temporarily trapped within these elongated structures, undergoing acceleration and transport processes that significantly differ from those observed in 2D or 2.5D simulations. Our findings reveal that these fine-scale structures act as efficient particle accelerators, surpassing the acceleration efficiency of single X-line reconnection events, and are capable of energizing electrons to energies exceeding 100 keV. High-energy electrons accelerated in different mini flux ropes follow distinct trajectories, due to spatially varying magnetic field connectivity, ultimately precipitating onto opposite sides of flare ribbons. Remarkably, double electron sources at the flare ribbons originate from different small-flux-rope acceleration regions, rather than from the same reconnecting field line, as previously suggested. Distinct small flux ropes possess opposite magn...