Theoretical and experimental study on jet formation and penetration of the liner loaded by electromagnetic force

Jet formation driven by strong magnetic field adopts the electromagnetic force to collapse the liner and breaks through the traditional jet forming mode of shaped charge, which relies on explosive. The influence of material strength on the liner deformation under low current is considered in this work to study the formation characteristics of the jet. Combined with the loading circuit, the jet formation and critical yield current (CYC) models are established. Subsequently, the CQ-4 device with 0.115 MJ energy is used to carry out electromagnetic loading experiments on the conical liners with a diameter of 10 mm and thickness of 1, 1.5, and 2 mm. The static penetration test method was used to test the jet power. The liners were all collapsed, and effective jets were formed by liners with 1 mm and 1.5 mm thickness. The depth of penetration (DOP) to the aluminum and steel targets were 30 mm and 12.5 mm, respectively. However, the 2 mm-thick liner almost did not have the ability to penetrate the steel target. The formation, movement, stretching, and penetration of the jets were calculation by theory and simulation. Results are in good agreement with the experiments. In the scope of this paper, the velocity and power of the jet increase with the decrease in liner thickness. The jet formation under theoretical calculation with and without material strength are compared and analyzed. The results indicated that the material strength cannot be ignored when the loading current is small. The formation characteristics of the liners under different loading currents are also calculated theoretically. The formation of the different liner elements under various currents are also calculated theoretically, and the peak current to CYC ratio is proposed to judge the formation state of the jet.