Laser prepulse effect on thermal smoothing of non-uniformities of target illumination is studied by means of 2D Lagrangian hydrodynamics simulation, based on parameters of real experiment. A substantial smoothing effect is demonstrated in case of an optimum delay between the prepulse and main heating laser pulse. The cause of enhancement of thermal smoothing effect by laser prepulse is the formation of long hot layer between the region of laser absorption and ablation surface. Comparison with experimental results is presented.

We present the results of the experimental testing of the laser facility LAMBDA, created and built at the Institute of Experimental Physics of the Russian Federal Nuclear Center for generation of quasi-steady-state laser fields in microvolumes.

The facility includes: a single mode generator of reference radiation (RR) producing about 10 mJ energy in a pulse of controlled length from 3 to 30 ns; a target chamber with an input objective focusing the RR beam to a micron-size spot, and a 280-mm-diameter parabolic mirror with the focal length also of 270 mm; a two-stage iodine amplifier with the small signal gain coefficient 3·105 per one pass, to the input of which radiation from the target chamber formed by the (microobjective + parabolic mirror) system is applied; a phase conjugating device with the system for the selection of the phase-conjugated component, which allows us to realize the pulse compression in the amplifier stages, and to provide the compensation of the optical aberrations after the second pass amplification and focusing of high-power radiation into the microvolume; a complex for diagnostics of plasma and laser radiation parameters.

The Petawatt laser at Lawrence Livermore National Laboratory (LLNL) has opened a new regime of laser matter interactions in which the quiver motion of plasma electrons is fully relativistic with energies extending well above the threshold for nuclear processes. In addition to ∼few MeV ponderomotive electrons produced in ultra intense laser-solid interactions, we have found a high energy component of electrons extending to ∼100 MeV apparently from relativistic selffocusing and plasma acceleration in the underdense preformed plasma. The generation of hard bremsstrahlung, photonuclear reactions, and preliminary evidence for positron-electron pair production will be discussed.

A possibility of input of high-power laser pulse into a cavity through a hole was studied by means of 2D numerical calculations. Such tasks appear in view of investigation of the effective targets with internal input of energy (Bessarab et al. 1992; Basov et al. 1998), “cannon-ball” (Hogan 1989), “Greenhouse” targets (Gus'kov et al. 1995).

We have used two Euler codes “NUTCY” and “FAKEL” to model the problems of laser beam input into a cavity through the holes.

The usual technique of the laser induced plasma spectroscopy (LIPS) spectra analysis relies on the use of calibration curves for quantitative measurements of plasma composition. However, LIPS calibration curves strongly depend on the material composition (the so-called matrix effect); thus, this standard approach to the LIPS spectra analysis is inadequate when precise information on unknown samples composition is required. In this paper we present a new procedure, based on LIPS, for calibration-free quantitative elemental analysis of materials. The new procedure, based on an algorithm developed and patented by IFAM-CNR, allows the overcoming of the matrix effect, yielding precise and accurate quantitative results without the need of calibration curves.

Opacity calculations for targets used in inertial confinement fusion (ICF) needs sophisticated atomic physics models, assuming a large number of configurations and transitions to simulate the plasma. Depending on the degree of accuracy for calculations of targets for ICF, some hydrodynamic-radiation codes use multifrequency opacities or well mean opacities.

In this work, using a sophisticated atomic physics code for LTE opacity calculations, that provides well multifrequency opacities or mean opacities, useful analytical opacity formulas for several single elements used in ICF have been generated, giving both Rosseland and Planck mean opacities as a function of the plasma parameters.