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Experimental studies are presented on composition, density and structure influence onto the neutron yield resulting from deuterium-containing target interaction with laser light of 1018 W/cm2. Experimental data is compared with theoretical and simulation results. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

In the paper the results of our experiment with flyer disks, accelerated to high velocities by the PALS iodine laser and subsequently creating craters when hitting massive targets , are presented. We have carried out experiments with the double targets consisted of a disk placed in front of a massive target part at distances of either 200 or 500 μm. Both elements of the targets were made of Al. The following disk irradiation conditions were used: laser energy of 130 J, laser wavelength of 1.315 μm, pulse duration of 0.4 ns, and laser spot diameter of 250 μm. To measure some plasma parameters and accelerated disk velocity a three frame interferometric system was used. Efficiency of crater creation by a disk impact was determined from the crater parameters, which were obtained by means of a crater replica technique. The experimental results concern two main stages: (a) ablative plasma generation and disk acceleration and (b) disk impact and crater creation. Spatial density distributions at different moments of plasma generation and expansion are shown. Discussion of the experimental results on the basis of a 2-D theoretical model of the laser — solid target interaction is carried out. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

In this paper we present experimental, theoretical, and computer simulation studies of craters formation produced by high power lasers in single and double layer targets. The experimental investigation was carried out using the PALS (Prague Asterix Laser System) facility working with two different laser beam wavelengths: λ1 = 1.315 μm and λ3 = 0.438 μm. Two types of targets made of Al were used: single massive targets, and double targets consisting of a foil or disk (6 μm thick for both cases) placed in front of the massive target part at a distance of 200–500 μm. Experiments with single massive targets were performed at laser intensities in the range of 1013–1015 W/cm2 by varying the laser beam diameters on the target surface from 70 μm up to 1200 μm (i.e. moving the target away from the focus). The double targets were illuminated by laser energies EL = 100–500 J focused always on a diameter of 250 μm. In all experiments performed the laser pulse duration was equal to 400 ps. 3-frame interferometry was employed to investigate the plasma dynamics through measurements of the electron density distribution time development as well as of the disks and foil fragments velocities. The dimensions and shapes of craters were obtained by crater replica technology and microscopy measurement. The experiments were complemented by a 2-D analytical theory and computer simulations, which helped at interpretation of the results. This way the values of laser energy absorption coefficient, ablation loading efficiency and efficiency of energy transfer, as well as two-dimensional shock wave generation at the laser-driven macroparticle impact were obtained from the measured crater parameters for both the wavelengths of laser radiation. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Numerical modelling was aimed at simulation of successive events resulting from interaction of laser beam-single and double targets. It was performed by means of the 2D Lagrangian hydrodynamics code ATLANT-HE. This code is based on one-fluid and two-temperature model of plasma with electron and ion heat conductivity considerations. The code has an advanced treatment of laser light propagation and absorption. This numerical modelling corresponds to the experiment, which was carried out with the use of the PALS facility. Two types of planar solid targets, i.e. single massive Al slabs and double targets consisting of 6 μm thick Al foil and Al slab were applied. The targets were irradiated by the iodine laser pulses of two wavelengths: 1.315 and 0.438 μm. A pulse duration of 0.4 ns and a focal spot diameter of 250 μm at a laser energy of 130 J were used. The numerical modelling allowed us to obtain a more detailed description of shock wave propagation and crater formation. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The results of experimental and theoretical investigations of craters originating in solid targets of different materials when powerful Nd:glass laser pulse irradiates the surface at flux densities in the range of 10[SUP10]-10[SUP14] W/cm[SUP2] are presented. The experimentally observed dependencies of crater depth and ablated mass on laser pulse energy and target material properties are analysed employing the theory of shock wave initiation and propagation under the action of the plasma-producing laser beam. From the comparison of the theoretically deduced and experimentally observed dependencies, a simple formula is derived allowing to determine the pressures in the shock wave and in the plasma corona using the measurements for the crater depth and ablated mass. [ABSTRACT FROM AUTHOR]