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The problem of spontaneous magnetic field generation with nanosecond laser pulses raises a series of fundamental questions, including the intrinsic magnetization mechanisms in laser-driven plasmas and the understanding of charge-discharge processes in the irradiated target. These two issues are tightly bound as the charge-discharge processes are defined by the currents, which have in turn a feedback by magnetic fields in the plasma. Using direct polaro-interferometric measurements and theoretical analysis, we show that at parameters related to the PALS laser system (1.315 µm, 350 ps, and 1016 W/cm²), fast electrons play a decisive role in the generation of magnetic fields in the laser-driven plasma. Spatial distributions of electric currents were calculated from the measured magnetic field and plasma density distributions. The obtained results revealed the characteristics of strong currents observed in capacitor-coil magnetic generation schemes and open a new approach to fundamental studies related to magnetized plasmas. [ABSTRACT FROM AUTHOR]

Emission of several tens of mA/cm^2 currents carried by MeV-protons is reported for plasmas produced by a beam of the 3-TW kJ-class Prague Asterix Laser System (PALS) focused onto foil targets of various thicknesses. The maximum proton energy of 4.2 MeV is observed at a modest irradiance (I\lambda^2\sim 2\times 10^16~W~cm^-2\mum^2). According to the maximum ion energy scaling EM\sim (I{\lambda}^{2})^{0.4} found for picosecond lasers such a value should be reached at I\lambda^2\sim 3\times 10^18~W~cm^-2~\mum^2. Enhancement of the maximum proton energy can be explained by nonlinear interaction of the PALS laser beam with the generated plasma. Nonlinear effects also result in enhancement in the yield of fusion neutrons from CD2 plasma. The obtained yield of 4\times 10^5 DD-neutrons per laser energy is comparable to those obtained by the use of ps- and fs-lasers irradiating targets with I\lambda^2\sim 10^19~W~cm^-2~\mum^2. [ABSTRACT FROM AUTHOR]

This paper describes the investigation of the influence of target material atomic number ( Z) on the laser-produced plasma pressure. For this reason, several target materials representing a wide range of atomic numbers ( Z = 3.5 - 73), i.e. plastic ( CH), Al, Cu, Ag, and Ta, were used. The results presented show that the plasma pressure decreases with growing atomic number but in a limited range of Z only. For higher Z, starting approximately from Z = 47 (Ag), the plasma pressure becomes constant, as confirmed by interferometric measurements and x-ray plasma imaging. [ABSTRACT FROM AUTHOR]

In this paper, we reveal the feasibility of obtaining laboratory craters to investigate planetary events such as meteorite craters. Experiments were performed by using 0.44-µm laser beam with energy of ≤ 15 J in 350 Ps (full-width at half-maximum) on aluminum targets. We obtain simple and complex craters similar in contour that are formed due to large meteorite impacts on the terrestrial surface. Simulations performed with the 2-D radiation hydrodynamic code MULTI help in understanding the origin of the experimentally observed central uplift of complex craters. [ABSTRACT FROM AUTHOR]