A. D. Matrosov

Possibilities of Controlling the Shaped–Charge Effect by Electromagnetic Actions

This paper deals with electromagnetic actions that allow one to control the shaped–charge effect at different stages of shaped–charge operation. A decrease in penetration of the shaped–charge jet is attained by passage of a powerful electric current pulse through it, production of an axial magnetic field in the shaped–charge liner immediately before shot, and production of a magnetic field in the conducting target material that is transverse to the direction of jet propagation. The action on a jet by low–frequency and high–frequency longitudinal magnetic fields and “mild” current action are directed toward increasing the penetration capability of a shaped–charge jet by increasing its ultimate elongation. Results of experimental and theoretical studies of different versions of electromagnetic actions are analyzed, and the associated physical effects are considered.

BEHAVIOR OF METALLIC SHAPED-CHARGE JETS WITH PASSAGE OF A PULSED ELECTRIC CURRENT THROUGH THEM

The paper reports results of experimental and numerical studies of the disruption of metallic shaped-charge jets by passage of a pulsed electric current through them. Experimental results are presented in the form of x-ray photographs of shaped-charge jets with and without a current and tables of penetration depths in targets. Numerical simulation of the disruption of shaped-charge jets with a current is performed for three possible mechanisms of disruption (development ofMHD instability of shaped-charge jets, volume fracture, and simultaneous development ofMHD instability and volume fracture). Numerical and experimental results are compared.

Influence of magnetic fields on shaped-charge performance

This paper deals with electromagnetic actions used to control the shaped-charge effect at different stages of shaped-charge operation. A decrease in penetration of a shaped-charge jet is attained by passage of a powerful electric current pulse through it, production of an axial magnetic field in the shaped-charge liner immediately before shot, and production of a magnetic field in the conducting target material that is transverse to the direction of jet propagation.

Mach stem formation in explosion systems, which include high modulus elastic elements

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 r...

Influence of Inert Copper and Silicon Carbide Inserts on Process of Detonation Transmission through Water

We have investigated the influence of fluoroplastic, copper, and silicon carbide inert inserts on the process of detonation transmission through water. Active and passive HE charges were molded from Comp B. On the rear end of the passive HE charge an identification steel specimen was mounted, which detected presence or absence of detonation. Inert inserts were shaped as square prisms of varying lengths, and were contained between active and passive HE charges without any clearance on the way of initiating shock wave with partial overlap of HE cross sections. It is shown that preloading of a passive HE charge with a shock wave transmitted through copper or ceramic inserts causes considerable desensitization of the Comp B. Ceteris paribus, the crash distance of detonation transmission for copper was equal to 74%, and for silicon carbide – to 60% of the distance for fluoroplastic. While performing the experiments with ceramic inserts we have observed cumulation phenomenon, which manifested itself as a hole in identification steel specimen with depth of about 10 mm. The surface of specimen had typical temper colours that demonstrated presence of high temperatures.

Pulsed power against terrorists

In recent years, the problem of the struggle against terrorists has become especially urgent. This has forced researchers and engineers to search for new opportunities for prevention terrorist activities. The paper reports on the possibilities of using various pulsed power technologies for disruption of shaped-charge jets (SCJ). This problem is especially urgent for the protection of objects whose damage can result in environmental disasters. The results from theoretical and experimental studies of SCJ disruption and reduction of jet penetration into various targets using electric pulsed power sources are analyzed. It is shown that a severalfold decrease in SCJ penetration into targets or even complete disruption of a SCJ before its interaction with a target can be achieved by controlling electric pulse parameters.

Prediction of the penetrating power of metallic shaped charge jets subjected to an intense electric current pulse

A method for evaluating the penetrating (piercing) power of shaped charges under the condition when an intense electric current pulse is applied to a shaped charge jet is developed. The buildup of waist-type MHD instability and the volume damage of the jet material are viewed as possible mechanisms behind a reduction of the penetrating power of a shaped charge jet under the current action. With this method, electrodynamic action parameters that provide a significant reduction of the penetrating power of a shaped charge jet are calculated for shaped charges of various penetrability.

New materials and technologies for pulsed power research and applications

Composites produced by explosive welding (bimetallic and multilayer materials) and composites with disordered structures produced by explosive compaction of powders were studied from the viewpoint of using them in railgun electrodes. Data on ablation are presented as a function of the electric current parameters. Results of metallographic and X-ray analysis of the post-shot electrode surfaces are reported. It is shown that using composite materials, it is possible to decrease the erosion of electrodes and increase the critical current density above which the erosion processes tend to increase considerably. The use of the method of explosive compaction of powders to produce high-temperature insulators and the barrels of railgun accelerators of projectiles is discussed.

Effect of external magnetic field on shaped-charge operaion

The present paper considers the possibility of using external magnetic fields for the antiterrorist protection of various objects against shaped-charge action by means of their magnetic screening - the creation of a magnetic field in the space ahead of the object being protected from attack.

Analysis of physical effects on the electrode surfaces in rail launchers

The paper analyzes the possibility of some physical effects occurring on the electrode surface in plasma-armature rail launchers when the linear current density is higher than the critical values. It is shown the melt on the electrode surface is unstable. An analysis of the possible development of a number of instabilities showed that under experimental conditions, Rayleigh-Taylor and Kelvin-Helmholtz instabilities and magnetohydrodynamic (MHD) instabilities due to the interaction of the flowing current with the self-magnetic field can develop over times much smaller than the discharge time. These instabilities can lead to the entry of the electrode material into the plasma armature and limit acceleration velocities of solids. X-ray recording of the electrode surface confirmed the presence of small-scale inhomogeneity and ejection of the material from the surface. Under certain conditions, the emergence of metal conducting jets from the electrode surface was detected.