Generation of shock waves and formation of craters in a solid material irradiated by a short laser pulse

The results of investigations are presented which are concerned with laser radiation absorption in a target, the plasma state of its ablated material, the energy transfer to the solid target material, the characteristics of the shock wave and craters on the target surface. The investigation involved irradiation of a planar target by a subnanosecond plasma-producing laser pulse. The experiments were carried out with massive aluminium targets using the PALS iodine laser, whose pulse duration (0.4 ns) was much shorter than the shock wave attenuation and on-target crater formation times (50–200 ns). The investigations were conducted for a laser radiation energy of 100 J at two wavelengths of 0.438 and 1.315 μm. For a given pulse energy, the irradiation intensity was varied in a broad range (10¹³–10¹⁶ W cm^-2) by varying the radius of the laser beam. The efficiency of laser radiation-to-shock energy transfer was determined as a function of the intensity and wavelength of laser radiation; also determined were the characteristics of the plasma plume and the shock wave propagating in the solid target, including the experimental conditions under which two-dimensional effects are highly significant.