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Magnetic reconnection in a flare current sheet is widely believed to be the main energy release process powering solar flares and coronal mass ejections (CMEs). Modeling this process and determining the channels for the energy release, mass motions, and heating has long been a major goal in space science. We present results from a two-fluid magnetohydrodynamic simulation of an eruptive flare/CME using a newly developed version of the Space Weather Modeling Framework that incorporates two major advances in numerical capability. First, we use the STatistical InjecTion of Condensed Helicity formalism for the energy buildup, so that we start with a potential-field minimum-energy state and slowly form a sheared filament channel over a polarity inversion line as is observed on the Sun. Second, we use a new formulation of the plasma energetics that is explicitly energy conserving while calculating separate electron and ion temperatures and separate parallel and perpendicular pressures, as desired. For this first simulation with our new model, we opted for the nonadiabatic heating to go solely into the protons and for an isotropic pressure. We discuss the resulting energetics of the reconnection and, in particular, the plasma heating in the reconnecting current sheets, mass acceleration, and shock formation. We also discuss the implications of our results for flare/CME observations and for understanding solar eruptions in general. 

Abstract Plasmoids (or magnetic islands) are believed to play an important role in the onset of fast magnetic reconnection and particle acceleration during solar flares and eruptions. Direct imaging of flare current sheets and the formation/ejection of multiple plasmoids in extreme-ultraviolet images, along with simultaneous X-ray and radio observations, offers significant insights into the mechanisms driving particle acceleration in solar flares. Here, we present direct imaging of the formation and ejection of multiple plasmoids in flare plasma/current sheets and the associated quasiperiodic pulsations (QPPs) observed at X-ray and radio wavelengths, using observations from the Solar Dynamics Observatory/Atmospheric Imaging Assembly, RHESSI, and the Fermi Gamma-ray Burst Monitor. These plasmoids propagate bidirectionally upward and downward along the flare current sheet beneath the erupting flux rope during two successive flares associated with confined/failed eruptions. The flux rope exhibits evidence of helical kink instability, with the formation and ejection of multiple plasmoids in the flare current sheet, as predicted in an MHD simulation of a kink-unstable flux rope. RHESSI X-ray images show double coronal sources (“looptop” and higher coronal sources) located at both ends of the flare current/plasma sheet. Moreover, we detect an additional transient faint X-ray source (6–12 keV) located between the double coronal sources, which is cospatial with multiple plasmoids in the flare current sheet. X-ray (soft and hard) and radio (decimetric) observations unveil QPPs (periods ≈ 10 s and 100 s) associated with the ejection and coalescence of plasmoids. These observations suggest that energetic electrons are accelerated during the ejection and coalescence of multiple plasmoids in the flare current sheet.