Scattering of laser radiation at the heating of low density foam targets

Summary form only given, as follows. An experimental study of the radiation scattered by laser heating of low density foam targets is presented. The experiments were carried out on a laser facility with wavelength 0.53 /spl mu/m, pulse duration 2.5 ns, focal spot diameter 15 /spl mu/m, flux density on target surface /spl sim/5 10/sup 14/ W/cm/sup 2/. The targets were prepared from porous polypropylene (CH)/sub x/ with average density /spl sim/0.02 g/cm/sup 3/ and cell size /spl sim/50 /spl mu/m. Both forward-, side- and back-scattered radiations including one created by the stimulated Brillouin scattering have been recorded, that enabled us to study the dynamics of the process of burning-through of the thick foam targets, the velocities of the plasma critical density motion as well as mass velocity of the plasma. The intensities of stimulated Brillouin scattering for the porous targets had the same value as for the solid ones (3-4% from laser density) but the spectral-temporal characteristics were quite different for these kinds of targets that confirms the different scattering properties and different ablation dynamics for the solid and the foam matter.