Bow shocks formed by a high-speed laser-driven plasma cloud interacting with a cylinder obstacle*

A bow shock is formed in the interaction of a high-speed laser-driven plasma cloud with a cylinder obstacle. Its temporal and spatial structures are observed by shadowgraphy and interferometry. The width of the shock transition region is ~ 50 μm, comparable to the ion–ion collision mean free path, which indicates that collision is dominated in the shock probably. The Mach-number of the ablating plasma cloud is ~ 15 at first, and decreases with time resulting in a changing shock structure. A two-dimension hydrodynamics code, USim, is used to simulate the interaction process. The simulated shocks can well reproduce the observed.