Search for new possibilities of attaining high launching velocities

The paper is concerned with analyzing the ultimate velocity versus the projectile mass at fixed acceleration distance for various methods of decreasing the current density at the rail-armature interface. The analysis is performed by numerical solution of the system of equations of unsteady diffusion of a magnetic field and unsteady heat transfer in a two dimensional formulation. Homogeneous and multilayer armatures, homogeneous rails, and rails with a high-resistive layer are considered. The results reported in the paper show that use of a resistive coating on the conductive side of rails is highly efficient at decreasing a current concentration on the rear side of the armature due to the high-velocity skin effect. This ensure a considerable decrease in the heating rate of the armature near the contact boundaries. As a result, the maximum velocity to which armature can be accelerated with retention of solid metallic contact with rails in a channel of a given length can be increased by a factor of 24, and the kinetic energy can be increased by a factor of 4-16 compared to the case of using rails without coating. Use of a multilayer armature with orthotropic electrical conductivity in combination with a resistive coating on the contact side of the rails allows one to attain high velocities and energy characteristics of the armature at short acceleration distances.