Nonlinear interaction of kinetic Alfvén waves and radio waves in the solar corona

Abstract

This paper investigates the nonlinear interaction of short wavelength kinetic Alfvén waves (KAWs) with extraordinary (x-) and ordinary (o-) mode radio waves using two fluid magnetohydrodynamics. The focus is on the interaction of a preexistent KAW with an ordinary electromagnetic wave, giving rise to an extraordinary electromagnetic wave. The equation governing the time evolution of the amplitude of the excited x-mode is derived. The growth time of the x-mode wave is determined and the corresponding interaction distance is computed for active regions in the low corona and for high corona. The nonlinear coupling appears to be quite efficient for reasonable amplitudes of KAWs in the corona, BA/B0 = 0.02-0.2. We suggest that this process provides a new possibility for the detection and remote sensing of coronal kinetic Alfvén waves by means of radio observations.