Purpose. To develop a laser method for initiating a converging cylindrical front of a detonation wave and a method for calculating the kinematic parameters of the cylindrical shell walls, accelerated by the pressure of the detonation products of an external explosive charge. Methodology. An experimental technology for the manufacture of a photosensitive explosive composite and an experimental technique for igniting the surface of its layer with an extended laser beam without the use of a fiber-optic cable are used. The results of simulation modeling the Monte Carlo method were used to study the effect of illumination on the process of ignition of explosives by laser pulsed radiation. For the selected type of photosensitive explosive composite, its explosive and optical characteristics, the distance from the surface of the explosive charge to the lens scattering the laser beam, and taking into account the total area of the expanded beam, the regularities of the distribution of the radiation energy density over the vertical and horizontal sections of the laser beam were studied. Findings. The analysis of the scientific and technical level of methods of shock-wave processing of materials in the region of ultrahigh pressures from the point of view of the fundamental value of the cumulation of energy in the waves of a converging cylindrical detonation and shock front is carried out. Physicomathematical modeling was carried out and the regularities of pressure increase in the wave front were established in the process of approaching the shell walls to the axis. The scientific results of modeling converging cylindrical shells under the influence of the pressure of the explosion products have been analyzed. A method for laser initiation of a converging cylindrical front of a detonation wave has been developed, and a method for calculating the kinematic parameters of the converging walls of a cylindrical shell has been proposed. Originality. A technique has been developed for determining the energy characteristics of an expanded laser beam, calculating the laser radiation energy required to initiate detonation simultaneously on the entire lateral cylindrical surface of a photosensitive explosive composite. The idea of technical implementation of the cumulation of converging cylindrical detonation and shock waves was developed further. A technique has been developed for the numerical determination of the change in the internal average compression rate of the shell during the movement of its walls towards the axis for various ratios of its external radius to the wall thickness and taking into account the increase in pressure in the converging detonation front. Practical value. For the first time, a method for laser initiation of a converging cylindrical front of a detonation wave was developed and a device was tested that forms a converging cylindrical front of a detonation wave and a corresponding shock front in the material under study by the impact of a metal shell converging to the axis. The core of the device is a laser explosive initiation system that uses light-sensitive explosive composites to initiate an explosive charge.

UDC 662.215 O. L. Kyrychenko 1 , cand. Sc. (Tech.), orcid.org/0000-0002-1331-9323, V. V. Kulivar 2 , orcid.org/0000-0002-7817-9878, O. V. Skobenko 2 , cand. Sc. (Tech.), Assoc. Prof., orcid.org/0000-0003-4606-4889, O. V. Khalymendyk 2 , cand. Sc. (Tech.), Assoc. Prof., orcid.org/A TecHNique TO MeASuRe SeNSiTiViTy OF eXPLOSiVeS TO THe eFFecT OF LASeR PuLSe RADiATiONPurpose. Improving reliability of the technique to determine sensitivity of explosives to laser pulse radiation involving the method for defining function of energy distribution in a laser beam.Methodology. Experimental studies, physical and mathematical modeling.Findings. The available techniques to determine sensitivity of explosives to laser pulse radiation have been analyzed. The tech nique to define the function of energy distribution in a laser beam is rather simple not requiring complex experimental equipment.Originality. Regularities of energy density distribution within the laser ray crosssection have been determined. It has been demonstrated that both theoretical and experimental dependences of energy density upon the laser ray radius are characterized by Gaussian distribution being little different from each other. Changes in radiation intensity within the laser ray crosssection have been determined experimentally.Practical value. Practical use of the laser initiation technique is connected with the improvement of the known methods to develop profiled detonation waves within the explosive charges as well as plane, cylindrical, conical, and spherical shock waves in different materials. Methods to develop such waves are characterized by maximum high repeatability of results and high efficiency in terms of minimum possible power consumption.

Purpose. To study changes in the microstructure of metals after exposure to high-energy plasma jets formed by the cumulation of gas-dynamic flows in a conical target. To estimate the expected state of matter in a strong shock wave compression, taking into account the change in volumetric energy density at the moment of transformation of a solid body plasma into nuclear matter. Methodology. The technique of laser initiation of a profiled front of detonation waves in explosive charges and the corresponding profile of shock waves in materials, methods and techniques for measuring the dynamic parameters of shock-compressed substances are used. Findings. An experimental study on the physicochemical state of a substance that has been processed with extremely high pressures and temperatures during compression by converging shock waves in conical targets has been carried out. Scientific results of physical and mathematical modelling of converging shock waves are analysed. Originality. For the first time, the formation of symmetric plasma jets during gas compression in conical targets has been experimentally observed. For the first time, metallo-physical studies on the microstructure of cast iron and steel have been carried out. These studies were made after the action of high-energy dense plasma jets with a temperature of (2.52.8) × 106K and a pressure 1.12 × 1012 arising from the collision of the jet with a barrier. Iron-55 and copper-64 isotopes were found in the cast iron microstructure near the surface formed by the action of the plasma jet. The main components of the plasma jet were gaseous oxygen, nitrogen, argon, and atomic iron, copper and gold. The fact of formation of isotopes is the result of nuclear reactions. One of the main conditions for the implementation of such reactions is a dense high-temperature plasma. It is assumed that under the action of a strong shock wave in a conical target, in addition to the synthesis reaction, other nuclear reactions with heavy elements can be realized. The ideas about the expected state of matter in a compression shock wave are presented, taking into account the change in the volumetric energy density at the moment of transformation of a solid body plasma into nuclear matter. Practical value. The proposed technique for conducting experimental studies on a shock-compressed substance under the action of extreme temperatures and pressures in conical targets using laser initiation of chemical explosives is of practical importance. The idea of the expected state of matter in the shock wave is also important.