Magnetic-field amplification in metal shaped-charge jets during their inertial elongation

This paper considers magnetic-field amplification in inertially elongating metal shaped-charge jets formed by explosion of a shaped charge with an axial field previously produced in the charge liner. The amplification is related to the effect of magnetic-field freezing in a conducting material and is due to the deformation of the jet material with particle elongation along the magnetic lines. The model of a uniformly elongating, conducting, incompressible, cylindrical rod was used to determine the nature of the field variation in the jet elements versus the magnetic Reynolds number determined by the electrical resistance of the material, the initial axial-strain rate, and the element radius. In high-gradient copper shaped-charge jets, the magnetic field can be amplified by more than a factor of five during elongation. It is shown that the joint action of the force and thermal factors accompanying field amplification in the jet material can lead to jet breakup with radial scattering of the material particles.