On current sheets in two‐dimensional ideal magnetohydrodynamics caused by pressure perturbations

In this paper it is shown that in ideal magnetohydrodynamics (IMHD) a two‐dimensional equilibrium with an X‐shaped neutral point (X‐point) configuration reacts to small and smooth perturbations of the plasma pressure by the development of sheets with singular current density while the X‐point structure is replaced by a different kind of configuration containing either cusp‐like or T‐shaped singularities. This behavior is demonstrated by computing the time dependent response to a suitable initial perturbation using a relaxation method within ideal MHD. The two‐dimensional configurations considered in this paper are motivated by models of space plasma systems like, e.g. the Earth’s magnetotail containing a distant X‐point where perturbations caused by the solar wind may force the formation of current sheets and the subsequent occurrence of magnetic reconnection.

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