Introduction. In recent years, several papers on the effect of a pulsed electric current on metallic shaped-charge jets (SCJ) have been published (see, for example, [1][2][3]). It has been shown experimentally and theoretically that the action of an electric current leads to a change in the jet "structure" and a decrease in the time of jet disruption, which, in turn, results in a severalfold decrease in penetration into the target. This effect is of great practical interest. The mechanisms of SCJ disruption by a pulsed current and their effect on the SCJ penetrationinto targets have been studied inadequately. The present paper reports results of experimental and numerical studies of SCJ disruption by an electric current.Numerical simulation was performed for the following three possible mechanisms of disruption: (a) development of MHD instability of SCJ; (b) volume fracture; (c) simultaneous development of MHD instability and volume fracture.The processes of formation, stretching, and penetration of SCJ with and without an electric current were simulated numerically.Results of the numerical simulation were compared with experimental data on the SCJ structure and penetration into steel and aluminum targets for various electric-pulse parameters.Diagram of Experiments. Diagrams of the experiments are given in Fig. la and b, where 1 is the shaped charge (SC), 2 is the electromagnetic-energy source, 3 are the electrodes, 4 are the inductive probes for measuring the current and the discharge-current derivative, 5 are the sites of radiography of the SCJ parameters (in an aluminum target and in free flight), and 6 is the target. In the diagram in Fig. lb, unlike in the diagram of Fig. la, the current can flow in the jet during jet penetration into the target. The cavern producing the target can act as an inverse current lead. In this case, the time during which the current acts on a jet element is much larger than that in the diagram shown in Fig. la. The experiments were performed with SC of 50-and 100-mm diameters and steel and aluminum targets. The energy source in the experiments was a capacitor bank with charging voltage of up to 5 kV and a capacitance of up to 20 mF. The current

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Results of experimental and numerical research of the Mach stem formation in explosion systems, which include high modulus elastic elements, are presented. The experimental data are discussed, and the analysis using ANSYS AUTODYN 11.0 is provided. It is shown that the phenomenon is reproduced for various high explosives. The Mach stem formation is observed in the conditions close to critical conditions of detonation transfer from an active to a passive HE charge. The best conditions for the Mach stem formation have been observed for TG-40/60 (Russian analog of Composition B) with silicon carbide insert heights of 16.5 mm, 18 mm, and 19.5 mm. The physical reason of the phenomenon is the propagation of a convergent detonation wave into highly compressed HE. The phenomenon is reproduced in numerical simulation with ANSYS AUTODYN 11.0. Calculated maximum value of pressure on the symmetry axis of passive HE charge was up to 1.25 Mbar. Results of metallographic analysis of steel identification specimen on the rear end of the passive HE charge indirectly confirm very high local pressures and temperatures for this scheme of explosion loading.

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