Nonlinear decay of phase - mixed Alfvén waves in the solar corona

This paper presents an analytical investigation of the nonlinear interaction of phase-mixed Alfvén waves in the framework of two-fluid magnetohydrodynamics. It focuses on the parametric decay of the phase-mixed pump Alfvén wave into two daughter Alfvén waves. This parametric decay is a nonlinear phenomenon which does not occur in ideal MHD since it is induced by the combined action of finite wave amplitude and the non-zero gyroradius of the ions. In contrast to intuitive expectation, the effects of the non-zero gyroradius of the ions are already important at length scales that are substantially longer than the ion gyroradius. The parametric decay occurs for relatively small wave amplitude and is more efficient than collisional damping.