To study the nature of magnetohydrodynamic (MHD) kink waves, the temporal behaviour of an initial kink perturbation of a typical coronal flux tube has been investigated in this paper. The flux tube has a transitional layer that separates the core region of the tube from the surrounding environment. In the transitional layer, the background density and magnetic field varies continuously from the internal to the external values. The magnetic field is straight and aligned with the tube axis in the internal and external regions of the flux tube, but is assumed to be twisted in the transitional layer. Hence, in the transitional layer the background Alfvén speed is inhomogeneous and perturbations become out of phase due to the process of phase mixing. Our result shows that as the energy of the wave transfers to the local Alfvén waves in the inhomogeneous region, the magnetic tension force becomes the dominant restoring force of the wave. The numerical results show that the nature of the small-scale oscillations in the transitional layer is determined by the ratio of the azimuthal components of the restoring forces.

中文翻译：

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太阳日冕中扭结MHD波的性质：磁扭曲和相混合

为了研究磁流体动力学（MHD）扭结波的性质，本文研究了典型日冕通量管的初始扭结扰动的时间行为。通量管具有过渡层，该过渡层将管的核心区域与周围环境分隔开。在过渡层中，背景密度和磁场从内部值到外部值连续变化。磁场是直的，并且在通量管的内部和外部区域中与管轴对齐，但假定在过渡层中发生了扭曲。因此，在过渡层中，背景Alfvén速度是不均匀的，并且由于相混合的过程，扰动变得异相。我们的结果表明，当波的能量转移到非均匀区域中的局部Alfvén波时，磁张力成为波的主要恢复力。数值结果表明，过渡层小规模振荡的性质由恢复力的方位角分量之比决定。