During the detonation of charges of plastic explosives based on PETN and RDX, the spatial structure of the arising flow and the degree of compression of the matter behind the detonation front were obtained using the synchrotron radiation facilities. The experiments were carried out with charges of small diameters, which made it possible to control the symmetry of the undisturbed charge of the explosive and the flow behind the detonation front. In addition, the advanced detector was used to increase the frame rate by 4 times in comparison with the authors' earlier works.

The jet structure from metal surface initiated by shock wave was investigated by small angle X-ray scattering (SAXS) technique for the first time. In these experiments used synchrotron radiation from the colliders VEPP-4. The beamlines 0-b at VEPP-3 and 8-b at VEPP-4 were used. These technique enables reliable detection of metal nanoparticles of 4 - 200nm size with exposure time 73 ps (at VEPP-4) for one frame and interval 125ns. It was found that jet from tin and tantalum foils impacted by pressed HMX gives a strong SAXS signal. This means that dust in jet contain nanoparticles. SAXS curve processing gives the nanoparticles size - about 100 nm. The flow of micro- and nanoparticles was about 4% by weight. The SAXS signal decreases with the usage of a less strong high explosive (plasticized PETN). It was found for the first time that the dust in jet has fine structure of density distribution which changes with time.

When a metal plate is subjected to a strong shock impact, its free surface emits a flow of particles of different sizes (shock-wave “dusting”). Traditionally, the process of dusting is investigated by the methods of pulsed x-ray or piezoelectric sensor or via an optical technique. The particle size ranges from a few microns to hundreds of microns. The flow is assumed to include also finer particles, which cannot be detected with the existing methods yet. On the accelerator complex VEPP-3-VEPP-4 at the BINP there are two experiment stations for research on fast processes, including explosion ones. The stations enable measurement of both passed radiation (absorption) and small-angle x-ray scattering on synchrotron radiation (SR). Radiation is detected with a precision high-speed detector DIMEX. The detector has an internal memory of 32 frames, which enables recording of the dynamics of the process (shooting of movies) with intervals of 250 ns to 2 μs. Flows of nano- and microparticles from free surfaces of various materials (copper and tin) have been examined. Microparticle flows were emitted from grooves of 50-200 μs in size and joints (gaps) between metal parts. With the soft x-ray spectrum of SR one can explore the dynamics of a single microjet of micron size. The dynamics of density distribution along micro jets were determined. Under a shock wave (∼ 60 GPa) acting on tin disks, flows of microparticles from a smooth surface were recorded.

Results of studying detonation processes in plastic-bonded TATB explosive, which are obtained by methods based on using synchrotron radiation, are given. In experiments, the detonating cylindrical charge was probed in a plane perpendicular to the axis. This allows us to obtain data on the dynamics of the mass distribution on the beam in a fixed section of the examined detonation flow. For cylindrical charges, the flow of detonation products is axisymmetric. This allows us to reconstruct the density distribution along the radius in the examined charge section on the basis of information obtained by probing in one perspective only. Data on the density distribution in the detonation front and behind the front for several high explosives are presented. The data on density distribution were used for reconstruction of all parameters (density fields, particle velocity vector, and pressure) of gas-dynamic flow of products of explosion. This method is based on numerical solution of the gas-dynamic problem formulated in accordance with a condition of experiment. The form of the equation of state is set, and a field of flow is calculated, in which the density distribution with that obtained in experiments is compared. The equation state parameters were chosen by minimizing the functional of root-mean-square deviations of the calculated and experimental x-ray "shadows" of the examined flow in selected nodes of the computational domain.This method allowed to obtain parameters of barotropic equation of state of detonation products and reconstruct agreed flow with full set of gasedynamic characteristics: density fields, particle velocity vector, and pressure.

The important role of the shape of the front during detonation wave propagation in gas mixtures was substantiated by K. I. Shchelkin during construction of the theory of spinning detonation. Subsequently, a unique relationship between the curvature of the front and detonation wave parameters has been repeatedly confirmed in experiments, including for condensed high explosives (HEs). The existence of this relationship formed the basis of the theory of the dynamics of the detonation front which had been developed by the end of the 20th century. This paper presents the results of a study of detonation front propagation in cylindrical samples of a low-sensitivity HE of different diameters with one-point and plane-wave initiation. A unique relationship between the detonation velocity and the curvature of the detonation wave front has been found. Ordinary differential equations describing two-dimensional steady-state detonation front profiles for HE charges in the form of a plate, a cylinder, and a ring were derived assuming that the detonation velocity depends on the curvature of the front. It was taken into account that the boundary angle between the normal to the front and the HE edge is unique for each combination of HE and liner material. It was found that the same detonation front profile corresponds to several combinations of liner material and the determining size of the charge (plate thickness, radius of the cylinder or the inner radius of the ring). A comparison of experimental front profiles near the edges of HE charges for these combinations provides data on the dependence of detonation velocity on the curvature of the front at low velocities corresponding to shock-induced detonation regimes. Analysis of previously obtained data for detonating ring charges of low-sensitivity HEs shows that as the detonation velocity decreases, the total front curvature tends to a limit of about 0.05 mm −1 , i.e., of the order of the inverse critical diameter. The limit of the front curvature allows predicting the critical detonation diameter.