  The shock structure of a plasmoid in magnetic reconnection in low-beta
plasmas is investigated by two-dimensional magnetohydrodynamic simulations.
Using a high-accuracy code with unprecedented resolution, shocks,
discontinuities, and their intersections are resolved and clarified. Contact
discontinuities emanate from triple-shock intersection points, separating
fluids of different origins. Shock-diamonds inside the plasmoid appear to
decelerate a supersonic flow. New shock-diamonds and a slow expansion fan are
found inside the Petschek outflow. A sufficient condition for the new
shock-diamonds and the relevance to astrophysical jets are discussed.
