Calculation and Verification on the Linear Instability of Shaped-Charge Jet Under Axial Pulse Current

摘要

To improve the defense capability of passive electromagnetic armor against shaped-charge jet (SCJ), according to the superposition principle and the linear perturbation theory, the SCJ disturbance control equations are constructed and the 3-D equation is reduced to 1-D equation, consequently, the instability growth rates of the pinch and kink of SCJ and the varying law of instability growth rates with time and yield stress are obtained under the axial pulse current, which indicate that the instabilities must occur as long as the perturbations exit. Meanwhile, the SCJ deformation can be calculated through numerical method. The pinching experiments with a 39.2-mm diameter armor-piercing projectile proceeded when the charging voltage is 5370 V and the peak current is 140 kA. The kinking experiments with a 1.75-mm diameter copper wire proceeded when the charging voltage is 5140 V and the peak current is 43 kA. The experimental results demonstrate that axial pulse current can destroy the SCJ because of necking or kinking perturbation and confirm the validity of the theoretical analysis.