From a viewpoint of the CSHKP model, upward reconnection jets are expected to arise at the onset of flares, which often make a significant contribution to the ejection of plasmoids. We performed MHD numerical simulations to study this highly dynamical process. Observationally, it is known that an eruptive plasmoid has three evolutionary phases; that is, the initial gradual rise, the short-term abrupt acceleration, and the long-lasting steady rise (Ohyama & Shibata 1997). By comparing simulation results with these observable features, we clarified the physical processes in those three phases (Figure 2). According to our results, a plasmoid starts rising slowly when a weak resistive process arises inside the underlying current sheet, then it is accelerated strongly once a fast magnetic reconnection occurs in the current sheet, and it finally rises at constant speed after a reverse fast-mode MHD shock is well developed at the bottom of the plasmoid (Magara, Shibata, & Yokoyama 1997).
Magara, T., Shibata, K., & Yokoyama, T. 1997, ApJ, 487, 437
Ohyama, M., & Shibata, K. 1997, PASJ, 49, 249