A universal pathway for solar flare eruptions

Abstract Solar flares are driven by a rapid release of magnetic energy accumulated quasi-statically in the solar corona. This energy accumulation, driven by magnetohydrodynamics processes, occurs in macroscale systems, while its release is governed by kinetic effects at microscale. The vast separation in system scales hinders the understanding of cross-scale energy cascades, leaving the question of how flare eruptions are initiated unresolved. Here, we report laboratory experiments that replicate the complete evolution of coronal magnetic energy from quasi-static accumulation to abrupt release and subsequent eruption. The experiments adopt the most common bipolar field in solar active regions, and drive magnetic energy accumulation with the most prevalent quasi-static stress. We show that the accumulated energy is stored in a magnetohydrodynamics-governed current sheet located at the polarity inversion line of the bipolar field. The current density and thickness of the current sheet continuously vary with energy storage, ultimately falls into kinetic regimes. We found that the current sheet, governed by kinetic effects, rapidly undergoes unstable fragmentation. Concurrently, plasmoid-mediated magnetic reconnection is triggered, initiating magnetic eruptions. Our results demonstrate a universal pathway for flare eruptions and how the current sheet and plasmoid-mediated reconnection function in this process, placing critical constraints on solar eruptions.