A. V. Babkin

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 the magnetic field produced in the liner of a shaped charge on its penetrability

It is established experimentally that generation of an axial magnetic field in the metal liner of a shaped charge immediately before ignition can drastically reduce its penetrability. Possible reasons for this effect are considered.

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.

Salient Features of Inertial Stretching of a High‐Gradient Conducting Rod in a Longitudinal Low‐Frequency Magnetic Field

From the viewpoint of the model of a uniformly stretching cylindrical incompressible rigid‐plastic conducting rod, the salient features of deformation of metal cumulative jets in a longitudinal low‐frequency magnetic field are considered. The electromagnetic processes proceeding in the jet segments when they enter or leave the region with a magnetic field have been investigated. It is shown that the electromagnetic forces arising as the result of deformation of the jet with the magnetic field that has penetrated into its material should inhibit the development of plastic instability, extending the stretching stage of the jet before it breaks up into separate segments and thus creating prerequisites for increasing its penetrating power capacity. The magnetic‐field parameters that enable one to expect a noticeable manifestation of the stabilizing effect have been estimated.

Possibility of generating strong magnetic fields in conducting materials by the action of high-velocity penetrators

The possibility of increasing the intensity of a magnetic field produced previously in a conducting medium moving under the action of a high-velocity penetrating body is analyzed. A simplified model of the interaction of an impactor and a conducting target with a transverse magnetic field is constructed within the framework of a one-dimensional scheme. It is shown that the degree of increase in the field intensity is determined by the relation between the magnetic-field compressibility and diffusion factors, and the corresponding dimensionless determining parameters is determined. Magnetic-field compression is estimated for a perfectly conducting medium and media with real conductivity. The significance of the thermal and mechanical effects accompanying the penetration of an impactor into a target with a transverse magnetic field is assessed.

Regularities of the stretching and plastic failure of metal shaped-charge jets

The results of physicomathematical modeling obtained within the framework of continuum mechanics by numerical solution of the two-dimensional axisymmetric nonstationary problem of the dynamic deformation of a compressed elastoplastic bar of variable section are presented. Dependences of the quantitative characteristics of stretching and breakup of a shaped-charge jet (the coefficients of ultimate and inertial elongation and the number of individual elements formed in breakup) on the jet parameters and the jet material properties are revealed by calculations. The calculated dependences are compared with experimental data for plastically failing jets of copper and niobium, and the character of the dependences is explained from the physical viewpoint.

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.

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.

Magnetic cumulative effect upon the explosion of a shaped charge with an axial magnetic field in its sheath

Experiments on creating an axial magnetic field in the metallic sheath of a shaped charge immediately before explosion are reported. Under such conditions, the penetrability of the charge is shown to decrease substantially. For instance, the penetration into a steel target is reduced more than twice when the initial field in the sheath is several tenths of a tesla. The most plausible reason for this effect is a drastic rise in the magnetic field (to a level as high as several hundreds of teslas) in the jet formation area, which disturbs the cumulative jet formation process. This pumping effect is presumably related to the magnetic field “freezing” into the deforming conductive material. Such a mechanism shows up when the tensile strain of the sheath’s fragments along the magnetic flux lines is significant. The ability of the deformation mechanism of field generation to disturb greatly the jet formation process upon collapsing the shaped charge sheath is substantiated by calculations.