Resonant Mode Conversion of Alfven Waves to Kinetic Alfven Waves in an Inhomogeneous Plasma

Kinetic Alfven waves (KAWs) are dispersive Alfven waves (AWs) with a perpendicular wavelength comparable to the ion (ion-acoustic) gyroradius or the electron inertial length and can play an important role in wave energy dissipation and particle energization. In this paper, we investigate the resonant mode conversion of AWs into KAWs for the case of an arbitrary angle alpha between the density gradient of the ambient plasma and the ambient magnetic field in an inhomogeneous two-temperature magnetoplasma. The results show that the mode conversion sensitively depends on the angle alpha, the density inhomogeneous gradient kappa rho(i), and the parallel wavenumber k(z)rho(i), as well as the ion to electron temperature ratio T-i/T-e. In particular, the excited KAWs are stronger when alpha is closer to 90 degrees and are hardly excited for 0 degrees <= alpha < 40 degrees. Moreover, the maximal strength of the excited KAW increases with the increase of k(z)rho(i) but decreases with the increase of kappa rho(i). Also, the maximal strength of the excited KAW has a larger value at larger T-i/T-e for 80 degrees < alpha <= 90 degrees. These results are helpful for our comprehensive understanding of the resonant mode conversion of AWs into KAWs in solar magnetic atmospheres when AWs originating from the photosphere propagate along solar magnetic fields into the corona.