Investigations of plasma jets produced by the action of a defocused laser beam on planar metallic targets and the interaction of supersonic plasma jets with dense gases (He and Ar) are presented. The experiment was carried out at the iodine laser facility (Prague Asterix Laser System (PALS)) using the third harmonic of laser radiation (0.438 µm) with a pulse duration of 250 ps (FWHM). In order to optimize the plasma jet parameters, the laser beam energy and the focal spot radius were changed in the ranges of 13–160 J and 35–600 µm, respectively. Besides, the focal point was located both before and inside the targets. The study was performed with the use of target materials of different mass densities (Cu, Ag and Ta). Finally, the optimized Cu plasma jets were used for shock wave generation in ambient gases of different pressures.Information about the geometry of plasma expansion, plasma dynamics and electron density distributions was obtained by means of a 3-frame laser interferometric system. Additionally, a Photonic Science PE7051 x-ray pinhole camera and the crater replica method for the reconstruction of crater parameters were used.Our experiment has shown that the plasma jet forming is a fundamental process which accompanies the expansion of the laser plasma produced by irradiating a massive planar target, made of a material of a relatively high atomic number, with a partly defocused laser beam. One can suppose that there are no laser energy limitations for the plasma jet creation. Illustrations of applications of such plasma jets for astrophysical and inertial confinement fusion investigations are also presented.
Study of channel formation and relativistic ultra-short laser pulse propagation in helium plasma