Transverse oscillations and damping of magnetic flux tubes with a thick transitional layer

Abstract

ABSTRACT In this paper, the magnetohydrodynamic kink waves and their damping are investigated in a thin coronal flux tube model. The thickness of the inhomogeneous transitional layer is of the order of the tube’s radius. The governing equations are solved analytically in all regions of the tube except for the thin dissipative layer. The dispersion relation is derived and solved numerically. The oscillation frequency does not vary much when varying the thickness of the transitional layer. When the transitional layer is thin, the damping rate of the kink wave increases significantly with the increase in the thickness of the transitional layer; however, when the transitional layer is thick, the damping rate does not vary much with the increase in the thickness of the transitional layer. For small values of the thickness of the transitional layer, our results are in agreement with results obtained in the thin tube, thin boundary approximation. In flowing tubes, the effect of flow on the damping rate of the waves depends on the direction of the wave propagation and plasma flow. The resonant instability of the kink waves in flux tubes with flowing transitional layer has been investigated.