[en] The dynamics of laser and X-ray radiation fields in experiments with cylindrical converter boxes (illuminators), which had earlier been carried out on the Iskra-5 laser facility (the second harmonic of iodine laser radiation, λ = 0.66 μm) was investigated in a sector approximation using the SND-LIRA numerical technique. In these experiments, the X-ray radiation temperature in the box was determined by measuring the velocity of the shock wave generated in the sample under investigation, which was located at the end of the cylindrical illuminator. Through simulations were made using the SND-LIRA code, which took into account the absorption of laser driver radiation at the box walls, the production of quasithermal radiation, as well as the formation and propagation of the shock wave in the sample under investigation. An analysis of the experiments permits determining the electron thermal flux limiter f: for f = 0.03 it is possible to match the experimental scaling data for X-ray in-box radiation temperature to the data of our simulations. The shock velocities obtained from the simulations are also consistent with experimental data. In particular, in the experiment with six laser beams (and a laser energy E_L = 1380 J introduced into the box) the velocity of the shock front (determined from the position of a laser mark) after passage through a 50-μm thick base aluminium layer was equal to 35±1.6 km s^-1, and in simulations to 36 km s^-1. In the experiment with four laser beams (for E_L = 850 J) the shock velocity (measured from the difference of transit times through the base aluminium layer and an additional thin aluminium platelet) was equal to 30±3.6 km s^-1, and in simulations to 30 km s^-1. (interaction of laser radiation with matter)

[en] The results of spectral calculations of the dynamics of laser radiation absorption and X-ray generation in a spherical box converter are presented for experiments on inertial fusion performed in the 1990s on the Iskra-5 facility. Numerical simulations were carried out taking into account the actual configuration of 12 laser beams and six apertures for introducing laser radiation. Calculations were performed in the sector approximation in which the inner surface of the box is divided into a certain number of regions or sectors. The movement of matter and radiation transport in each sector were calculated by using the one-dimensional spectral nonequilibrium dynamics program. Spectral calculations showed a strong inhomogeneity of irradiation of a capsule in the M-band region (2.7-2.9 keV). It is shown that the spectrum-averaged root-mean-square inhomogeneity of the X-ray energy flux on the capsule (during the time of its compression) is about 2.5% for laser beams of the same energy and is about 3% if the characteristic energy misbalance between the beams is taken into account. (interaction of laser radiation with matter. laser plasma)

[en] The dynamics of laser and X-ray radiation fields in experiments with spherical boxes was numerically investigated in a sector approximation using the SND-LIRA numerical code. The experiments were performed on the Iskra-5 laser facility at a wavelength λ=0.657 μm (the second harmonic of iodine laser radiation). The characteristics of X-ray generation were investigated with the inner surface of a converter box coated with different-Z materials (Au, Cu, Mg). With lowering Z, the laser energy absorption coefficient k_a decreases and there occurs a lowering of the effective X-ray radiation temperature. Our calculations reveal a strong dependence of the results on the electron free-streaming flux limitation f. In particular, on lowering f from 0.1 to 0.03 for a conventional box with a gold coating, the coefficient k_a decreases from 0.83 to 0.5 and the peak X-ray radiation temperature drops from 170 to 150eV. In these calculations, the rms nonuniformity of the X-ray irradiation of a capsule with thermonuclear fuel amounted to 1%-3%.

[en] We report the results of numerical analysis of radiation dynamics (laser absorption and X-ray generation) by using SNDLIRA code in a combined box used in the X-ray opacity measurements on the 'Iskra-5' facility (laser radiation wavelength, λ = 0.66 μm; laser pulse duration, τ_0.5 ≈ 0.6 ns; and energy, 900 J). Combined boxes used in these experiments comprised three sections: two illuminators delivering laser radiation and a central diagnostic section with a test sample. We have proposed a scheme for step-by-step calculation of the heating dynamics of the sample under study in a three-section hohlraum. Two designs of a combined box, which differ in the ways the laser radiation is injected, are discussed. It is shown that the axial injection of the beams results in intense secondary laser irradiation of the illuminator edge which leads to its partial disruption and penetration of laser radiation into the central diagnostic section. In this case the sample under study is exposed to additional uncontrolled action of scattered laser radiation. Such an undesirable action may be avoided by using the lateral injection of the beams through four holes on the lateral side of the illuminators. For the latter case we have calculated the heating dynamics for the sample and found an optimal time delay for an X-ray probe pulse. (interaction of laser radiation with matter. laser plasma)

[en] The interaction of plasma clouds generated during laser irradiation of a spherical target in a background gas with a magnetic field was studied on the MKV-4 test bench of the Iskra-5 facility. The dynamics of the plasma cloud expansion in a 300- to 500-Oe magnetic field was investigated using magnetic and probe diagnostics. The results obtained are compared with calculations by different models of laser plasma diffusion in a magnetic field

[en] Extracts of biologically active compounds (BACs) from chamomile flowers grown in the Samara region produced by extraction with subcritical water, as well as aqueous ethanol solutions of various concentrations at 150 and 200°C and 5 MPa were investigated using the methods of UV spectroscopy, gas chromatography coupled with mass spectrometry (GC–MS), high-performance liquid chromatography (HPLC), and gravimetry. Identification of BACs in the produced extracts was carried out using reactive gas chromatography.

[en] Results are presented from studies of the spectral characteristics of a glowing plasma object that forms behind a shock wave propagating in a background gas at a pressure of 1 Torr after laser irradiation of a spherical organic target in the MKV-4 device (a component of the Iskra-5 facility). The experimental data are compared to the results of calculations

[en] An investigation is made of the dynamics and visible-range luminosity of the plasma cloud produced behind the front of a shock wave in air at a pressure of 1 Torr. The shock wave was produced on introducing the radiation of the twelve-channel Iskra-5 laser facility with a total energy of ∼2300 J into a hollow spherical plastic target of mass ∼10^-4 g. Experimental data are compared with simulations. (laser plasma)