Ultimate kinematic characteristics of rail electromagnetic launchers with an external magnetic field

Abstract

Summary form only given. Thermal limitations due to currents are the main factors limiting the attainment of high projectile velocities and reducing th e life of rail electromagnetic launchers of solids. The heat load on the rails and the armature can be reduced by decreasing the current flowing through them, but this also reduces the electromagnetic accelerating force and the maximum velocities of solids of a given mass at a given distance of acceleration. One method of reducing the current through the rails and the armature without reducing the electromagnetic force acting on the armature is the use of the external magnetic field generated by the currents flowing in additional rails (coils) parallel to the main channel of the accelerator. This paper presents the results of a three-dimensional numerical simulation of Joule heating of the armature and rails in rail launchers with one or two additional rails producing an external magnetic field. The purpose of this study was to investigate the possibilities of reducing the Joule heating rate of the armatures during acceleration and increasing the ultimate (under heating conditions) kinematic characteristics of the launchers by selecting the optimal location of additional rails and optimizing the magnitude of the current pulse in them. The ultimate projectile velocity was calculated from the condition that the Joule heating temperatures of the armature and rails in the acceleration process are not higher than the melting point of the armature and rail materials. It is shown that by choosing the optimal location of the rails producing the additional magnetic field with respect to the accelerator channel and the magnitude of current in the m, one can greatly reduce the thermal limitations in electromagnetic launchers of solids with a metal armature and considerably increase the ultimate kinematic characteristics in crisis-free modes of operation.