Study on the Selection of Coil Energization Directions in Multistage Synchronous Induction Coil Launcher

Abstract

In order to enhance the initial velocity and energy conversion efficiency of multi-stage synchronous induction coil launchers, the direction of coil energization for the drive coils is studied. There are typically two energization methods for multi-stage launching devices: (1) PP (Positive-Positive), where positive current is applied to all drive coils, and (2) PN (Positive-Negative), where currents in opposite directions are alternately applied to the drive coils. A finite element model of a four-stage coil launcher is established in ANSYS2022R2, and the acceleration effects of the armature under different inter-stage distances are analyzed for two energization methods. The study reveals that the PN configuration does not always result in higher armature velocities compared to the PP configuration under different inter-stage distances. The theoretical explanation is provided for the variations in the forces exerted by the previous and next drive coils on the armature during the acceleration process. It is found that the magnitude of the induced current in the previous and next drive coils during the launch process is influenced by the inter-stage distance, which in turn affects the electromagnetic thrust coupled with the armature. Thus, the method of determining the direction of current in the launching device coil is obtained.