Onset of an explosive instability in a Hamiltonian dynamical system associated with collisionless magnetic reconnection

A neoclassical reduced magnetohydrodynamic model of collisionless magnetic reconnection is revisited. Starting from a nonlinear equilibrium that is known to be unstable and to develop a magnetic island, here it is shown that once the magnetic flux and vorticity fields reach a quasi-steady saturated state, the remaining two dynamical fields – the parallel ion velocity and the electron pressure – undergo a finite-time explosive instability. A self-similar analysis within the reconnection layer yields an explicit divergence of these fields at a finite blow-up time tX .