EXPERIMENTAL-STUDY OF LASER AND WAVELENGTH DEPENDENCES OF LASER PLASMA COUPLING, TRANSPORT, AND ABLATION PROCESSES IN PLANAR GOLD TARGETS

Gold-layered-target experiments at 1.06-mu-m have been performed in order to study the laser and wavelength dependence of the laser-light absorption, the energy transport, and the ablation at irradiances of 10(12)-10(15) W/cm2. The results of the measured electron temperature and mass-ablation rate can be put in the form T(e) (eV) congruent-to 506[I(L)(W/cm2)/10(14)]0.27 x[lambda(L)(mu-m)]0.25 and m(kg/cm2 sec) congruent-to 162[I(L)(W/cm2)/10(14)]5/9 [lambda(L)(mu-m)]-4/3. A good agreement with the self-similar solutions presented by Sigel et al. [Phys. Fluids B 2, 199 (1990)] indicates a radiative transport for lambda(L) < 0.044-mu-m and a thermal transport for lambda(L) > 0.044-mu-m. In the latter case (lambda(L) > 0.044-mu-m), a very good agreement is also obtained for 10(10) W/cm2 less-than-or-equal-to I(L) less-than-or-equal-to 10(16) W/cm2 with the model of Dahmani et al. [Phys. Fluids B 3, 1232 (1991)]. The results presented here clarify some aspects concerning the x-ray conversion and transport in high-Z plasmas.