Ultimate Kinematic Characteristics of Rail Electromagnetic Launchers With an External Magnetic Field

The thermal limitations due to the circuit current are the major factors preventing the attainment of high projectile velocities and acceptable service life of railguns. To reduce the thermal load on the rails and armatures, it is necessary to reduce the amount of current flowing through them, but this decreases the electromagnetic accelerating force and limits the maximum velocities of projectiles of a given mass at a predefined acceleration distance. One method of lowering the current without reducing the electromagnetic force on the projectile is to use a railgun with augmenting rails. This paper presents the results of 3-D numerical simulations of the Joule heating of armatures and rails in railguns with one and two pairs of augmenting rails. The objective of this paper is to reduce the rate of Joule heating of armatures during acceleration and to increase the ultimate (under heating conditions) kinematic characteristics of the railguns by choosing the optimal configuration of the outer turns and optimizing the current pulse in the augmenting rails. The ultimate projectile velocities are obtained when the Joule heating of the rails and armature by electric current during the shot does not tend to increase the temperature at any point of the railgun above the melting point of the rail and armature materials. It is shown that by controlling the position and total current in the augmenting rails, it is possible to significantly reduce the thermal limitations during high-velocity electromagnetic acceleration of solids and increase the ultimate kinematic characteristics of railguns in crisis-free acceleration regimes.