Acceleration Mechanism and Experimental Research of Multi-Stage Synchronous Induction Coilgun Based on Magnetic Field Arrangement

Multi-stage synchronous induction coilgun is one of the important research aspects of the electromagnetic launch. Researchers mainly focus on the optimization of the geometrical dimension and parameters for the multi-stage launcher, pulsed power supply, armature, and so on, in order to achieve the best matching between parameters. Based on the basic principle of multi-stage induction coilgun, the acceleration mechanism is investigated in terms of the magnetic field arrangement. First, a field-circuit coupled model for a 15-stage coilgun is built. Through analyzing the velocity profile and the distribution of current density vector on the armature, it is considered that the armature is affected by the magnetic field generated by frontal stages and current stage during the launching process, so the braking force and pushing force both act on the armature. Therefore, the system conversion efficiency is affected. In order to reduce the braking force and increase the variation of the magnetic field, the direction of the magnetic field is changed. The distribution of the current density vector on the armature and transition process for the variation of the magnetic field is analyzed. The simulation results show that the muzzle velocity can be increased significantly by changing the direction of the magnetic field. The acceleration mechanism of the inconsistent direction of the magnetic field is different from that of a consistent direction. The current density on the armature is increased dramatically in the transition area, which is beneficial to increase the magnetic pushing force. A previously built 15-stage coilgun was used to validate the method. The launching experiments are carried out under the condition of the consistent direction and inconsistent direction of the magnetic field. The experiment results show that the system conversion efficiency is improved significantly for the inconsistent direction of the magnetic field. It provides a valuable reference for multi-stage induction coilgun design.