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Title: Numerical simulation of three-dimensional X-ray and laser field inhomogeneities in experiments with spherical box converters on the Iskra-5 facility

Abstract

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)

Authors:
; ;  [1]
  1. Russian Federal Nuclear Center 'All-Russian Scientific Research Institute of Experimental Physics', Sarov, Nizhnii Novgorod Region (Russian Federation)
Publication Date:
OSTI Identifier:
21466652
Resource Type:
Journal Article
Resource Relation:
Journal Name: Quantum Electronics (Woodbury, N.Y.); Journal Volume: 37; Journal Issue: 4; Other Information: DOI: 10.1070/QE2007v037n04ABEH013219
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CAPSULES; COMPUTERIZED SIMULATION; INERTIAL FUSION DRIVERS; KEV RANGE; LASER RADIATION; ONE-DIMENSIONAL CALCULATIONS; PHOTON BEAMS; RADIATION TRANSPORT; SPECTRA; SPHERICAL CONFIGURATION; THREE-DIMENSIONAL CALCULATIONS; X RADIATION; BEAMS; CONFIGURATION; CONTAINERS; ELECTROMAGNETIC RADIATION; ENERGY RANGE; IONIZING RADIATIONS; RADIATIONS; SIMULATION

Citation Formats

Bondarenko, S V, Dolgoleva, G V, and Novikova, E A. Numerical simulation of three-dimensional X-ray and laser field inhomogeneities in experiments with spherical box converters on the Iskra-5 facility. United States: N. p., 2007. Web. doi:10.1070/QE2007V037N04ABEH013219.
Bondarenko, S V, Dolgoleva, G V, & Novikova, E A. Numerical simulation of three-dimensional X-ray and laser field inhomogeneities in experiments with spherical box converters on the Iskra-5 facility. United States. doi:10.1070/QE2007V037N04ABEH013219.
Bondarenko, S V, Dolgoleva, G V, and Novikova, E A. Mon . "Numerical simulation of three-dimensional X-ray and laser field inhomogeneities in experiments with spherical box converters on the Iskra-5 facility". United States. doi:10.1070/QE2007V037N04ABEH013219.
@article{osti_21466652,
title = {Numerical simulation of three-dimensional X-ray and laser field inhomogeneities in experiments with spherical box converters on the Iskra-5 facility},
author = {Bondarenko, S V and Dolgoleva, G V and Novikova, E A},
abstractNote = {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)},
doi = {10.1070/QE2007V037N04ABEH013219},
journal = {Quantum Electronics (Woodbury, N.Y.)},
number = 4,
volume = 37,
place = {United States},
year = {Mon Apr 30 00:00:00 EDT 2007},
month = {Mon Apr 30 00:00:00 EDT 2007}
}
  • 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{sub 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, whichmore » 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)« less
  • 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, {lambda} = 0.66 {mu}m) 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 lasermore » 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{sub 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-{mu}m thick base aluminium layer was equal to 35{+-}1.6 km s{sup -1}, and in simulations to 36 km s{sup -1}. In the experiment with four laser beams (for E{sub 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{sup -1}, and in simulations to 30 km s{sup -1}. (interaction of laser radiation with matter)« less
  • We describe an improved Slater average-ion model employed in the numerical-theoretical analysis of experimental data, which were obtained in the investigation of X-ray spectral path lengths performed on the Iskra-5 laser facility at the All-Russian Scientific Research Institute of Experimental Physics (VNIIEF). The proposed model permits determining the spectral characteristics of the X-ray radiation with an accuracy of a few electronvolts. We outline the results of simulations of experiments with X-ray radiation-heated aluminium and germanium specimens of initial thickness of {approx}0.1 mm, in which absorption lines arising from 1s-2p transitions in Al and the absorption band arising from 2p-3d transitionsmore » in Ge were recorded.« less
  • A spectrograph complex, developed for the ISKRA-4 and ISKRA-5 facilities, is described. The complex was developed to study continuous and line spectra in the 0.06-3 keV range. It comprises diffraction-grating, multilayer-mirror, and grazing-incidence crystal spectrographs. Recorded laser plasma X-ray spectra are compared with the ones predicted by the gas-dynamical theory. 9 refs., 2 figs.
  • We set forth the data of experimental investigation of X-ray spectral absorption coefficients in the 1.1 - 1.6 keV photon energy range for Al and Ge specimens bulk heated by soft X-ray radiation. Two experimental techniques are described: with the use of one facility channel and the heating of specimens by the X-ray radiation from a plane burnthrough target, as well as with the use of four channels and the heating by the radiation from two cylindrical targets with internal input of laser radiation. The X-ray radiation absorption coefficients were studied by way of transmission absorption spectroscopy using backlighting X-raymore » radiation from a point source. The results of investigation of X-ray spectral absorption coefficients on the 1s - 2p transitions in Al atoms and the 2p - 3d transitions in Ge atoms are presented.« less