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.