In this paper, we study the shock compressibility and spall strength of composites reinforced with carbon fibers and glass fibers using a VISAR laser interferometer. A two-wave configuration is shown to form in both composites during the propagation of a shock wave along the fibers. The two-wave configuration in fiberglass is observed up to a shock-compression pressure of 18 GPa while in a carbon-fiber reinforced polymer (CFRP), it is recorded in the entire studied range of pressures up to 33 GPa. The Hugoniots and spall strength of composites were determined at various fiber orientations.

We performed experiments on shock compression up to pressures of 36 and 50 GPa of mixed samples of silicon nitride and potassium bromide, placed between copper plates that serve as walls of a recovery ampoule. For comparison, similar experiments were carried out by the conventional compression of a mixture of silicon nitride and copper powder. The loading of the samples was fulfilled by means of aluminum flyers accelerated by products of explosion to a few kilometers per second. The pressure profiles prior to a shock wave entering the sample and after its runout were measured with the use of manganin sensors. It is found that for the configurations of the experimental assembly used, the pressure in the samples, accumulated by circulating the shock wave, reaches the desired value before unloading. Based on estimates of the rate of heat transfer between the components, it is shown that thermal equilibrium can be set during the existence of high pressure in the mixed samples. Within the framework of the single-temperature medium model, the equations of state of the samples are derived, and the temperatures of their shock compression are calculated. Using these equations, we performed numerical simulations that showed good agreement with the experimental data.

The volume dependence of the band gap for aluminum hydride (alane) is compared at high static and dynamic pressures. Room temperature high pressure isotherm data and multiple-shock conductivity data were used for the reconstruction of the volume dependence of the alane band gap in the pressure range 50-75GPa. The traditional exponential relationship for the temperature dependence of semiconductor conductivity with the power law volume dependence of the aluminum hydride band gap is suggested in the regions of volumes 11.5-12.5cm3/mol, pressures 50-75GPa and temperatures 1270-1370K.

The experimental multiple-shock technique and a computer-code simulation were used for investigations of electrophysical properties of dense molten sodium up to pressures of 230(5) GPa and temperatures up to 8000(600) K. The multiple-shock data show that the resistivity of shocked sodium increases with pressure and temperature up to 270(30) mu Omega cm. This change was interpreted via the pressure-induced metal-semiconductor transition in shocked molten sodium.

Survival of the production target in successive experiments (with a repetition rate of 1 Hz) over an extended period of time is one of the key problems encountered in designing the Super-FRS (Superconducting Fragment Separator) at the future Facility for Antiprotons and Ion Research (FAIR). Because of the difficulties involved in construction of a liquid jet metal target, it is highly desirable to employ a solid production target at the Super-FRS. However, with the high beam intensities that will be available at the FAIR, the production target may be destroyed in a single experiment due to high specific energy deposition by the beam in the target material. The level of specific energy deposition can be reduced to an acceptable value by increasing the beam focal spot area. However, the spot size is limited by requirements of achieving good isotope resolution and sufficient transmission of the secondary beam through the system. The resolving power of the fragment separator is inversely proportional to the X-dimension of the focal spot whereas the transmission depends on Y-dimension only. It has been previously shown [Tahir et al., 2005c] that an elliptic focal spot with appropriate dimensions, will fulfill the above two conditions simultaneously and will also have a large enough area to reduce the specific energy deposition to an acceptable level for certain beam intensities of interest. In this paper we present numerical simulations of thermodynamic and hydrodynamic behavior of a solid graphite target that is irradiated by 1 GeV/u uranium beam in the intensity range of 10(10)-10(11) ions per bunch with a bunch length = 50 ns, These simulations have been carried out using a three-dimensional computer code, PIC3D, that includes elastic-plastic effects. This theoretical work has shown that up to a beam intensity of 10(11) ions/bunch, one can employ a solid target while for higher intensities the target will be destroyed due to thermal stresses induced by the beam. It has also been found that a circular focal spot leads to minimum thermal stresses as it generates minimum pressure gradients compared to an elliptic focal spot, for the same specific energy deposition. Moreover, the stress level increases with an increase in the ellipticity of the focal spot. It is therefore recommended that one should use a circular focal spot for lower intensities provided that the criteria for isotope resolution and transmission are fulfilled.

The Deep Impact active space experiment has been done to study a hypervelocity collision of a metal impactor with the nucleus of the comet 9P/Tempel 1. In this work we present results of numerical modeling in comparison with corresponding experimental data. The modeling has been done with the use of 3D “finite-size particle in cell” method. The computational setup corresponded to impact angle of 30 degree with respect to the horizon for different materials forming the surface of the comet nuclei, i.e., ice and sand. Conclusions are made for the possible composition of the comet.

The numerical modeling of hypervelocity impact has been done with the use of method of “finite‐size particle in cell”. We carried out calculations using both multi‐phase and simplified caloric equations of state (EOS) in 3D setup for a spherical lead impactor penetrating flat lead plate with a velocity of 6.6 km/s. This impact velocity produces melting in the shock wave and a strong evaporation in the release wave. The processes of crater and debris cloud formation and their dynamics have been investigated. Results of numerical modeling, such as the density distribution in inner space, the form and spatial size of debris cloud, have been compared with experimental x‐ray shots. We found that parameters of gas dynamic flow, such as pressure and density, are different for multi‐phase and caloric EOS. One should note that both EOS describe shock‐wave data with good accuracy. The analysis proved that the quality of modeling results significantly depends on the equation of state used.

This research presents results of 3D modeling of impacts at different velocity and impactor geometry. Original finite-size particle in cell method was used as a tool for modeling performed. The results of modeling were compared with experimental x-ray photographs and experimental values of hole diameter and debris cloud dimensions. The influence of material properties models used has been investigated.

This research presents a new “finite-size particle in cell” method developed for numerical modeling of processes at high energy density. It uses the Lagrangian–Eulerian representation of media which allows one to match contact and free surfaces and to calculate flows with strong deformations. Efficient models of thermodynamic properties, elastic–plastic deformation and fragmentation have been employed in the gas dynamic code adapted for parallel computations. 3D and 2D numerical modeling of plate penetration by impactors of different geometry has been done in a wide range of velocities. The influence of used materials properties models on numerical results has been investigated.

A hypervelocity collision of a metal impactor and the nucleus of the Tempel 1 comet is to be carried out in July 2005 in the framework of the Deep Impact active experiment in space. This paper discusses certain observable consequences of this impact. Numerical simulation of the impact process made it possible to evaluate the diameter of the impact-produced crater as a function of the initial density and porosity of the cometary nucleus. A substantial part of the shockwave-compressed cometary material that is evaporated at the unloading stage may become heated to temperatures on the order of (1–2)×104 K. A change in the chemical composition of the hot vapor in the process of its expansion was computed using a model elemental composition of the cometary nucleus; this may prove useful for determining the parameters of the flash induced by the impact in the visible optical, UV, IR, and radio wavelength bands.