Duration and distance of a laser-driven shock wave formation in a plasma with subcritical density

Abstract

Theory and computational results are presented through the generation and propagation of a plane laser-driven shock wave in a substance with a density less than the critical plasma density. A model of the phenomenon is developed, the essence of which consists in the formation of pressure behind the front of the laser-driven ionization wave, which provides hydrodynamic motion with the speed exceeding the speed of the ionization wave front and the sound speed in unperturbed matter ahead of it. The dependences of the duration and distance of shock wave formation on the intensity and radiation wavelength of the impacting laser pulse, as well as on the density of the target substance, are established. The results are discussed for the conditions of irradiation of targets with a density up to 0.1 mg cm−3 by a pulse of short-wavelength radiation of the first–third harmonics of the Nd laser with an intensity of 1012−1015 W cm−2.