Abstract
Magnetic reconnection dynamics due to the nonlinearly destabilized double tearing mode (DTM) is simulated, focusing on the nonlinear growth phase in the framework of reduced resistive magnetohydrodynamics (MHD). The nonlinearly explosive growth of the DTM accompanying fast magnetic reconnection is found to result from a secondary instability, the mechanism of which consists of the sequential unstable modulation due to two- dimensional distortion of magnetic islands and modification of the nonlinear current profile. The trigger dynamics of the nonlinear growth phase is illustrated via the investigation of the evolution of both the kinetic and magnetic energies of the secondary instability.
