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Content available remote Plasma jet generation by flyer disk collision with massive target
EN
In this paper, results from experiments with Al flyer targets (disks with a diameter of 300 mm and a thickness of 6 mm) accelerated at first to high velocities by PALS iodine laser pulses (with an energy of 130 J, pulse duration of 400 ps, a wavelength of 1.315 mm, and laser spot diameter of 250 mm), subsequently creating craters after their collisions with massive Al targets (placed at a distance of the order of 200 mm) are presented. To measure the plasma density evolution a three frame interferometric system was employed. The experimental results demonstrate that the flyer disk-massive target collision generates an axial plasma jet corresponding to a flat shock wave propagating in a massive target. This form of the shock wave was deduced from a crater trapezoidal shape which was reconstructed by means of crater replica technique.
2
Content available remote High power laser interaction with single and double layer targets
EN
Results of extended complementary experimental and computer simulation studies of craters formation produced by high power lasers in single and double layer targets are presented. The experimental investigation was carried out using the PALS (Prague Asterix Laser System) facility working with two different laser beam wavelengths: L(lambda)1 = 1.315 žm and L3 = 0.438 žm. Two types of targets made of Al were used: single massive targets and double targets consisting of foils or disks (6 and 11 žm thick for both cases) placed in front of the massive target at distances of 200 and 500 žm. The targets were illuminated by laser energies EL= 130, 240 and 390 J always focused with diameter of 250 žm. In all experiments performed the laser pulse duration was equal to 400 ps. The 3-frame interferometry was employed to investigate the plasma dynamics by means of the electron density distribution time development, as well as the disks and foil fragments velocity measurements. Dimensions and shapes of craters were obtained by crater replica technology and microscopy measurement. Experimental results were complemented by analytical theory and computer simulations to help their interpretation. This way the values of laser energy absorption coefficient, ablation loading efficiency and efficiency of energy transfer, as well as 2-D shock wave generation at the laser-driven macroparticle impact, were obtained from measured craters parameters for both wavelengths of laser radiation. Computer simulations allowed us to obtain an energy absorption balance of incident laser energy for both wavelengths employed.
EN
Experimental and theoretical results of investigations of the iodine laser - Al solid target interactions on the PALS (Prague Asterix Laser System) facility are presented. The experimental investigations of laser interaction with massive Al targets devoted to shock wave propagation in solids and crater formation physics are presented. Experiments were performed with the use of high intensity laser pulses (1013 15 W/cm2) for two laser wavelengths (0.438 mi m and 1.315 mi m) and four laser beam radii (from 35 mi m up to 600 ěm). The crater dimensions were measured using optical microscopy and a wax-replica technique. Plasma expansion out of the target was measured via three-frame interferometry. Theoretical model of the postpulse crater formation by the shock wave propagating and decaying in solids after the end of the laser pulse is presented and applied for the explanation of the results obtained in experiments.
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