[en] New self-similar solutions describing a compression of dense internal regions of single component laser targets are obtained. The solutions constructed represent a process of unlimited energy concentration when approaching the moment of collapse and they are fit for description of non-isentropic compression regimes at which the initial perturbation is a convergent wave. It is pointed out that for shell targets the optimum time dependence of laser power at compression degrees of the 10³-10⁴ order differs from the known asymptotic dependence. The described self-similar solutions give a correct quantitative description of compression and heating of dense regions of laser targets and can be used for optimization of laser compression regimes and estimation of conditions of thermonuclear radiation ignition at laser initiation

[en] The method for removing the fundamental F^- mode, maintaining the pressure values in the Lagrangian particles is proposed. The solution obtained is based on the class of new polytrops with inverse density run and relative polytrop indices

No abstract available

[en] A dust-impact mass analyzer (DIMA) designed for determination of the chemical composition of cosmic dust of the Halley comet, placed aboard the ''Vega'' and ''Jotto'' space probes is theoretically analysed. DIMA represents a combination of a dust accelerator and a time-of-flight mass spectrometer (TFMS) of the ''mass-reflectron'' type. The problem on motion ofthe collisionless, cold plasma cloud expanding by inertia in the external electric field is theoretically solved. The solution is carried out within the scope of the perturbation theory. Non-steady-state flow and concentration of impurity ions are small parameters in this problem. The solutions obtained are used to built the theory of TFMS analysis in case when the ion source is the plasma cloud formed during collision of an ultrahighspeed dust with an obstacle. TFMS resolution capability, angular distribution of ions behind the removing screen and TFMS carrying capacity are calculated for multicomponent plasma. A case of oblique impact, when dust flies at an angle to the anode surface, is considered. It is shown that in this case only certain lines of the mass spectrometer can be lost due to proper ions carrying by a ion collector

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No abstract available

[en] The analysis of stationary solutions are of special importance in the Rayleigh-Taylor instability theory. By the methods of computer algebra, the paper shows that the multiplicity of these solutions forms a single-parameter family F. The application of a new 2D hydrodynamic numeric method, developed in this work, allows to establish which of the solutions from F family is formed form the periodic initial perturbation. This solution proved a to be of the smallest radius of curvature and limiting in the F family. The spectrum of harmonics is calculated for the first time. The existence of nonperiodic stationary solution with a solitary jet under relevant boundary conditions is predicted

[en] This paper considers the effect of an ultrashort laser pulse on a thin gold film on a glass substrate at a focal spot size near 1 μm. We analyse the motion and thermal history of a film that has peeled off from the substrate in the heating spot as a consequence of melting. The detached zone is shown to form a dome-shaped bump whose motion is hindered by surface tension. After the dome stops and turns back, towards the substrate, a jet begins to grow on its top. Concurrently, because of the heat dissipation in the film, melt recrystallisation begins, involving first the dome and then the jet. The liquid part of the jet elongates and breaks up into droplets because of the Plateau – Rayleigh instability development. The formation of a neck and the detachment of the last droplet occur in the solidification zone between the crystalline and liquid parts of the jet. The propagation of the crystallisation zone in the jet leads the necking process, so neck disruption occurs in the solid phase under nonequilibrium crystallisation conditions (the melt temperature is hundreds of kelvins lower than the melting point), at limiting mechanical stress and at high deformation rates. As a result, the jet transforms into a high needle with an extremely small tip radius (a few nanometres). (paper)

[en] The problem concerning the asymptotic behaviour of hydrodynamic Rayleigh-Taylor instability is investigated. The solution is based on decomposition into the Fourier series. A system of equations for harmonic amplitude up to the sixth one inclusive is derived. This algebraic system with a high nonlinearity order can be accurately solved

[en] The work begins with a presentation of results concerning periodic Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) dynamics. The periodic RT flows are considered in 2D and 3D cases. The periodic RM flows are considered in a 2D case. Nonstationary and steady-state statements of RT and RM problems are given. Nonstationary statements of RT and RM problems are given in the 2D case. Steady-state statements of RT and RM problems are considered in the 2D and 3D cases (RT) and in the 2D case (RM). Questions about turbulence are given in the second part of the work. The spatial structure of the may dimensional periodic solutions is studied. It is known that there are two important features in the flows under consideration: the bubble envelope and the jet ''phase''. Spatial structures of the 2D and 3D flows are compared in the report. It is shown that the apices of the bubbles are isolated points and the bubble envelopes in both flows are qualitatively similar; the difference has a quantitative character. On the contrary, the jet ''phases'' differ qualitatively in the 2D and 3D cases. In the 2D case in the plane picture, the jets are separated from each other. In this picture they are isolated fingers. In the 3D case, near the bubble envelope after some time of development following after cos kx cos qy type initial perturbation, they are not the isolated fingers. They form a structure of the intersecting walls. We see, thus, that the 2D and 3D cases are topologically different. Most powerful ejections of dense fluid are in the points where these wall jets intersect each other. (author)