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High gradients of electron temperature appear in plasma corona under direct laser irradiation of inertial confinement fusion targets. This results in nonlocality of heat transport. Such effect influence the efficiency of laser absorption, redistribute heat fluxes and could preheat plasma ahead the front shock wave, therefore alter the compression adiabat. Ignition requires a specially tuned compression dynamics, so such an effect should be taken into account. Target simulations with nonlocal models show the decrease of compression efficiency and hot-spot parameters degradation compared to local models: Spitzer–Härm model with and without flux-limiter.

An Erratum to this paper has been published: https://doi.org/10.1134/S0021364022390023

The numerical results for cryogenic direct drive targets of megajoule facilities with radiation in the second and third harmonics of a Nd laser are presented. The calculations were performed with the 1D radiation hydrodynamics code ERA with the laser light absorption model that takes into account stimulated Brillouin scattering (SBS), generation of fast electrons in the processes of two-plasmon decay (TPD), and stimulated Raman scattering (SRS). The verification of the developed models was carried out on the basis of the comparison with experiments performed at the OMEGA and NIF facilities. The ignition margin (WQ) of nonuniform fusion targets with an allowance for energy losses due to radiation transfer and heat conduction from the hot spot was the objective of the target optimization. The calculations showed that SBS and target heating by fast electrons generated in TPD and SRS fatally reduce WQ of targets with a CH ablator for the megajoule laser with wavelength λ = 0.53 µm. The possibilities of decreasing these effects by replacing a CH ablator with a glass ablator and reducing the laser intensity upon increasing the target aspect ratio are considered. However, in both cases, WQ remains substantially below unity for the laser with wavelength λ = 0.53 µm. The ignition margin increases by a factor of ∼2 upon transition from the second to the third harmonic of a Nd laser. A glass ablator almost eliminates fast electrons in calculation with the laser wavelength λ = 0.35 µm. In this case, if SBS is reduced by a factor of 3–4 via shifting the laser emission lines in the neighboring channels by Δμ ≈ 10–20 A, the ignition margin WQ ∼ 2 and a fusion energy yield of ∼50 MJ are obtained in the 1D calculation for a laser energy of ∼2 MJ and the third harmonic of a Nd laser.

We study the influence of turbulent mixing on the development of thermonuclear flashes in the surface layers of neutron stars. A simple K e model that includes various physical processes is used to describe the turbulent processes. In contrast to the widespread mixing-length theory, the K e model does not require using additional dimensional parameters, traces the development of turbulence in dynamics, describes the various turbulence development scenarios (gravitational and shear instabilities, convection, semiconvection, etc.) in a unified way, and can be used in multidimensional numerical simulations. Empirical constants of the model are chosen on the basis of experimental data and direct numerical simulations of typical processes. We have used the Era and Tigr-3T software packages to numerically simulate thermonuclear flashes in the accretion-renewable atmospheres of neutron stars. Turbulence is shown to accelerate significantly the transport of released energy to the stellar surface. Mixing equalizes the concentrations of matter components throughout the burning layer and increases the amount of matter involved in the thermonuclear burning during a flash.

This paper reports the results of numerical modeling of the magnetic dipole moment produced by displacement of the Earth's magnetic field in a one‐kiloton underground nuclear explosion in a cavity. It is shown that with increase in cavity size, the magnetic dipole moment increases, reaching 107 A · m2, which is approximately 200 times the magnetic dipole moment from a camouflet explosion. A factor of 100 decrease in the initial air density in cavities with radii of 10 and 20 m results in a reversal of the direction of the magnetic dipole moment vector.

A mathematical model is described of the relativistic electron beam interaction with a nitrogen plasma at GOL-3-II facility. 1 Results of simulated plasma heating and plasma-induced ultra-violet and X-ray radiation spectra are presented.

Investigation of mechanism of plasma ions heating in a multimirror magnetic trap became actual due to the essential progress in experiments on GOL-3 facility at Budker Institute of Nuclear Physics. The mechanism of fast (in comparison with the Coulomb one) acceleration and heating of ions in a multimirror trap with injection of a powerful relativistic electron beam is discussed.

The paper gives a brief description of ASTRAL code package for astrophysics simulations, including features in the implementation of basic physical processes and two tests. A sketch of the object code structure is provided.

Summary form only given. Essential progress has been achieved on GOL-3 experimental facility (Novosibirsk) in recent years. Deuterium plasma with density 1015 cm-3 is heated by relativistic electron beam up to temperatures in order of 2 keV, both for electron and ion plasma components. Neutron output has been obtained for the plasma. The paper presents one possible way to increase neutron output. It can be done if small condensed matter target with density about 1 containing deuterium would be placed into the plasma. Estimations of neutron output for different targets are presented in the paper, obtained by means of numerical simulation. The basis of the calculation model is physico-mathematical model of hot plasma interaction with solid target. Equations of gas dynamics, kinetics of level population of multi-charged ions and radiation transfer in lines and continuum, kinetics of chemical decomposition of target matter or its evaporation are solved self-consistently. Calculations of neutron output for targets of frozen deuterium, lithium deuteride and deuteration polyethylene have been done. Estimation of tritium accumulation in reaction Li3 6 + n0 1 = H1 3 + He2 4 for lithium deuteride target is presented. Neutron output has been calculated for targets with deuterium-tritium mixture as well. Size of target with maximum neutron output has been obtained

The 1-D ERA code results of the optimization of the hohlraum temperature time-dependence and the target design to obtain gain of 20 needed for Engineering Test Facility (ETF) are presented. In accordance with the ERA code calculations, it is possible to achieve the thermonuclear energy yield of 100 MJ from the practicable shell targets with the diameter of 4,3 mm, the initial aspect ratio of 10-20, the DT-ice layer thickness about of 100 /spl mu/m frozen on inner surface of glass shell if the hohlraum temperature rises linearly in time during 15-20 nsec up to maximum values of 250-350 eV. The X-ray spectrum and the neutron-induced radioactivity are calculated.

1D ERA code allows to simulate the kinetic of ionization and nonequilibrium radiation transfer in line and continua. This code is expanded to account the processes of ions ionization and excitation in the field of laser radiation. For the descriptions of the processes the wave equation is solved. The results of calculations of X-ray yield at the irradiation of Al plate by picosecond laser pulse at intensity of 1016−1017 W/cm2 are presented.

The results of 1D-ERA and 2D-TICR, 2D-OMEGA codes calculations of compression and burn of indirect-driven targets for the thermonuclear ignition and Hybrid Nuclear-Fusion Reactor are presented.

The results of the ICF indirect‐driven targets optimization performed by ZARYA/ERA code for a better insight into the requirements imposed on both target designs and hohlraum drive temperature to gain the ignition with laser of minimum power are presented. Two modification of cryogenic shell targets for hohlraum drive temperatures in the range of 0.25–0.38 keV are proposed for the ignition. The 500 TW lasers are needed to perform such investigations.

The implosion dynamics of argon plasma is investigated using 1D two‐temperature radiation MHD code ZARYA. A detailed configuration atomic model has been employed to calculate the line emission. The model includes effects of line opacity, Doppler effect due to ions motions and ionic state variation. The state populations are calculated using a set of time‐ dependent atomic rate equations for electron collisional excitation and de‐excitation, dielectronic and radiative recombination, photoexcitation and others processes. The ionization state of the plasma is calculated self‐consistently with line and continuum radiation transport. Perfect gas equations of state taking into account the energy of ionization are used for electrons and ions pressure and internal energy calculations.Anomalous resistivity mechanism phenomenologically considered is low‐ hybrid drift instability model. Microturbulence effects are included by increasing the resistivity coefficients. Finally, a comparison is made with calculations us...

The results of the computation analysis of the turbulent mixing in the direct and indirect‐driven shell targets are presented. The simulation were carried out by TURLINA‐code based on phenomenological mixing model. The effects of the mixing are studied numerically for the SOKOL‐laser experiments and for the indirect‐driven targets. The comparison of the TURLINA‐code simulations with the SOKOL experimental X‐ray picture gives the evidence for reduction of turbulent mixing at the ablation front in experiments with shell targets. The estimates of the initial roughness and the effect of ablation‐stabilization influence on the turbulent mixing and neutron yield from DT‐filled glass microballoon are carried out. The allowable compression asymmetry for thermonuclear ignition is discussed.

A mathematical model and an implicit method of numerical modelling are described for the physical processes in micro-targets, irradiated by a laser pulse. The efficiency of the method is illustrated by the computation of model problems.