Dynamical Analysis of the Nonlinear Growth of the [Formula presented] Resistive Internal Mode

A dynamical analysis is presented that self-consistently takes into account the motion of the critical layer, in which the magnetic field reconnects, to describe how the [Formula presented] resistive internal kink mode develops in the nonlinear regime. The amplitude threshold marking the onset of strong nonlinearities due to a balance between convective and mode coupling terms is identified. We predict quantitatively the early nonlinear growth rate of the [Formula presented] mode below this threshold.