We discuss the feasibility of developing a high-power thermonuclear neutron source driven by laser pulses. Using one-dimensional numerical simulations for targets made in the form of double-sided cones, for an absorbed Nd-laser energy of similar to 1 MM (at the second and third harmonics) and pulse duration of 10-20 ns it is possible to achieve a neutron yield at a level of 10(16)-10(17) per shot. This neutron yield is a prerequisite to the commencement of work to develop a hybrid nuclear-thermonuclear reactor.

The gravitational instability of a homogeneous isotropic infinite gravitating gaseous medium is investigated in order to study the physical processes that take place during the formation of the solar planetary system. The analytical and numerical solutions of the motion equations of such a medium are considered in two approximations: cold gas and gas at a finite temperature. The real solutions describing the behavior of both wave density disturbances of a homogeneous medium and single disturbances are obtained. Waves of gravitational instability whose amplitude grows exponentially and whose highs and lows, as well as their nodal points, retain their positions in space follow the basic laws of Jean’s model. The authors interpret this wave of instability as an analogue of protoplanetary rings, which can be formed in protoplanetary disks. According to the numerical calculation results, the reaction of a homogeneous gravitating medium to the single initial perturbation of its density is significantly different from the laws of Jean’s model. The instability localized in single initial perturbations extends to the region λ < λ J , although in this case the growth of the perturbation density is considerably less than for λ > λ J . It is discovered that the gravitational instabilities in the region λ > λ J suppress sound. It is shown that, without taking into account the rotation of the Sun’s protoplanetary disk medium, its critical density in the event of a large-scale gravitational instability is about four orders of magnitude smaller than the critical density in accordance with the theory of planet formation by the accumulation of solids and particles.

The nonstationary energy transfer by fast charged particles, i.e. products of thermonuclear reactions, is simulated, and the effect of this process on the compression and burning of thermonuclear targets is numerically investigated.

The article presents calculation results, which were received for the implosion of the typical cryogenic thermonuclear direct-drive targets that are intended for use at the OMEGA facility, NIF and Russian laser facility. The compression and burning characteristics, which were obtained using various numerical codes of different scientific groups, are compared. The data indicate good agreement between the numerical results. Various sources of target irradiation inhomogeneity and their influence on the implosion parameters are considered. The nominal scales of these disturbances for various facilities are close to each other. The main negative effect on the efficiency of compression and burning is due to the accidental offset of the target from the center of the chamber.

The paper considers the numerical design of heavy ion fusion (FIHIF) targets, which is one of the branches of controlled thermonuclear fusion (CTF). One of the important tasks in the targets design for controlled thermonuclear fusion is the energy embedding selection whereby it is possible to obtain "burning" (the presence of thermonuclear reactions) of the working DT region. The work is devoted to the rapid ignition of FIHIF targets by means of an additional short-term energy contribution to the DT substance already compressed by massively more longer by energy embedding. This problem has been fairly well studied for laser targets, but this problem is new for heavy ion fusion targets. Maximum momentum increasing is very technically difficult and expensive on modern FIHIF installations. The work shows that the additional energy embedding ("igniting" impulse) reduces the requirements to the maximum impulse. The purpose of this work is to research the ignition impulse effect on the FIHIF target parameters.

The paper is devoted to numerical designing of cylindrical microtargets on the basis of shock-free compression. When designing microtargets for the controlled thermonuclear fusion, the core tasks are to select geometry and make-up of layers, and the law of energy embedding as well, which allow receiving of "burning" of deuterium-tritium mix, that is, the existence of thermonuclear reactions of working area. Yet, the energy yield as a result of thermonuclear reactions has to be more than the embedded energy (the coefficient of amplification is more than a unit). So, an important issue is the value of the embedded energy. The purpose of the present paper is to study the extraction of energy by working DT area in one-cascade and two-cascade targets. A bigger extraction of energy will contribute to a better burning of DT mix and a bigger energy yield as a result of thermonuclear reactions. The comparison of analytical results to numerical calculations is carried out. The received results show advantages of a two-cascade target compared to a one-cascade one.

The objective of this study was by use of mathematical simulation methods to create an opportunity of a thermonuclear target (k f ) gain of the order of 1 at the 1 MJ laser energy level. The calculations were performed in two codes with a comparison of their results. It is shown that in the direct drive mode it is possible to obtain a neuron yield an order higher than that obtained in experiments on the NIF (LLNL, the United States) installation in the indirect drive target.

We report the results of numerical analysis of radiation dynamics (laser absorption and X-ray generation) by using SND-LIRA code in a combined box used in the X-ray opacity measurements on the 'Iskra-5' facility (laser radiation wavelength, lambda = 0.66 mu m; laser pulse duration, tau(0.5) approximate to 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.

The model of nonstationary nonequilibrium radiating plasma is developed by considering level kinetics and radiation transport in spectral lines self-consistently. A spherical target explosion and radiation caused by a laser pulse is simulated. The two-temperature 1D Lagrange gasdynamic equation is solved numerically. The radiation field and the level kinetics are considered self-consistently by two different approaches: by using interpolation between the precalculated tables of spectral parameters and by accounting for the detailed level kinetics included in-line in the gasdynamic calculations. Conversion efficiency of EUV radiation is estimated for lithium and tin plasma. It is important for EUV lithography used for microchip production. The conversion efficiency under the optimal parameters of laser pulse is as follows: for lithium it is 1%, and for tin, it is 5%, and it is in a good agreement with the experimental data.

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 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-mu m 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).

The problem of simulating neutron-nuclear processes in hybrid microtargets with an external energy source has been considered. A mathematical model of interaction between neutrons and nuclei based on radiation transport multigroup equations is developed. The results of the numerical calculations of the microtarget with a thin layer of 238U are presented. The influence of the neutron model various simplifications on the neutron-nuclear processes in the microtarget is shown.

We present the numerical design of a two-cascade target. The desired target design is intended to provide a shock-free compression of the central DT core, where the fusion reactions take place. We obtain the formula for the energy deposition into each cascade internal layer for both known and unknown energy depositions into the external target layer. The two-cascade target design helps to increase the energy deposition into the DT layer and therefore decrease the energy required for the target ignition.