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Accelerating Shock Waves in a Laser-produced Density Gradient

We study the possibility of creating decreasing density gradients under laboratory conditions using high-energy lasers. The idea is to study the propagation of shock waves in such laser-produced "atmospheres" in order to test theories on shock acceleration and shock front stability. We investigate theoretically two experimental designs that could address this question. We consider first the case of a discrete, two density step package, showing that this experiment can result in very strong shock acceleration (a factor of 4). We finally consider the case of a continuously decreasing density package, obtained by indirect illumination of a plastic target by a thin gold foil. We obtained a 20 μm thick exponential atmosphere, which is a perfect laboratory in which to study the stability of accelerating shock waves in a decreasing density gradient.