IMPULSIVELY GENERATED MHD WAVES IN A CORONAL PLASMA

Impulsively generated nonlinear waves in smoothed slabs of arbitrary beta plasma are studied numerically by an application of the code that uses the flux corrected transport method. Numerical results show that a total reflection which occurs in the region of a low Alfven speed leads to trapped waves. These waves propagate along the slab and exhibit periodic, quasi-periodic and decay phases. As a consequence of a difference in the waves speeds time signatures of slow and fast waves are shifted in time. An interaction between these waves can generate a longer lasting and complex quasi-periodic phase of the fast wave. A slow standing wave which is initially generated in a closed slab can excite another standing wave at the x-point of the same local cusp speed. At early stages of its time evolution the excited wave possesses twice smaller wavelength than the original standing wave. Later on both waves have the same wavelength. These waves communicate themselves by a fast wave which is forced by the original slow wave.