Flux rope acceleration and enhanced magnetic reconnection rate

A physical mechanism of flares has emerged from our 2.5-dimensional resistive MHD simulations of the dynamical evolution of current sheet formation and magnetic reconnection and flux rope acceleration subject to the continuous, slow increase of magnetic shear in the arcade. With anomalous nonuniform resistivity in the current sheet the simulation results relate the flux rope's accelerated rising motion with an enhanced magnetic reconnection rate and thus an enhanced reconnection electric field in the current sheet during the. are rise phase. The simulation results provide good quantitative agreement with observations of the acceleration of flux ropes, which are manifested in the form of ejected soft X-ray plasmas, erupting. laments, or CMEs. For the X-class. are events studied in this paper the peak reconnection electric field is similar toO(10(3) V m(-1)) or larger, enough to accelerate electrons to over 100 keV in a field-aligned distance of 0.1 km and produce impulsive hard X-ray emission observed during the. are rise phase.