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 flare 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 filaments, or CMEs. For the X-class flare events studied in this paper the peak reconnection electric field is ~O(103 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 flare rise phase.
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机译：在我们的2.5维电阻MHD模拟中，火炬的物理机制已经出现，该模拟是电流曲线形成的动态演变以及磁重新连接和磁通量绳加速度受拱廊中磁剪连续缓慢增加的影响。在电流板中存在异常的不均匀电阻率的情况下，模拟结果将磁通绳的加速上升运动与提高的磁重连接率联系在一起，从而将火炬上升阶段电流板中的重新连接电场增强。仿真结果与磁通量绳加速的观测结果提供了良好的定量一致性，这些观测值以喷射的软X射线等离子体，喷出的细丝或CME的形式表现出来。对于本文研究的X级耀斑事件，峰值重新连接电场为〜O（103 V m-1）或更大，足以在场距0.1 km的距离内将电子加速至超过100 keV，并产生脉冲硬在耀斑上升阶段观察到X射线发射。
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