Three-dimensional Simulation Study of the Magnetohydrodynamic Relaxation Process in the Solar Corona. II.
Three-dimensional dynamics of solar coronal magnetic loops, which is caused by the photospheric twisting motion, is investigated in detail by using magnetohydrodynamic numerical simulations. It is found that, as a result of the rising of the magnetic loops, isolated flux tubes (plasmoids) are generated on top of the loops through magnetic reconnection. During the reconnection process, the magnetic energy of the mode coupled with the potential field is partially converted into the mode decoupled from it. We also analyze the linear stability of the coupled mode and reveal that it is destabilized when the loop height and the magnetic helicity exceed the critical values predicted from the bifurcation theory. Furthermore, we reveal that three-dimensional mode couplings have the effect of concentrating the helicity into an unstable mode, as well as the effect of reducing the growth rate of the instability.