Electromagnetic Launcher

Abstract

Any Coilgun has many advantages over other electromagnetic launchers. Coilgun electric coils are placed along the channel through which a projectile moves without friction losses. The coils are switched on and off sequentially to accelerate the projectile and push it out of the channel. The projectile is also equipped with a cylindrical power coil to increase the accelerating force. For the same purpose, the inner diameter of the coil Dc is made slightly larger than the outer diameter of the projectile Dp. But this is the problem of the low energy intensity of all known coilguns. This is their bottleneck. Actually, the electromagnetic energy transferred to the inductance of the coil Lc is proportional to the square of the coil diameter Dc. At the same time, the mass of the accelerated projectile Mp is proportional to the square of the diameter of this cylindrical projectile Dp. Usually Dc = (1.1–1.3) Dp, and the hard connection between the transmitted energy and the mass of the projectile is trying to change by accelerating the ring. In this paper, a patented new type of coilgun is considered. The diameter of the coil Dc is much larger than the diameter of the projectile Dp, for example, 10 times. Ceteris paribus, this allows significantly increase the energy transferred to the coil, for the example under consideration, by 100 times. To immediately transfer this energy into the space occupied by the projectile with the diameter Dp, a non-magnetic, electrically conductive shield, for example, made of aluminum, is placed in the space Ac between the coil and the channel. The shield has a disc shape with a central hole and at least one radial cut, preventing eddy currents from closing around the coil axis. Eddy currents in the shield displace the magnetic flux from the Ac space into the coilgun channel, increasing the density of the magnetic field in comparison with the prototype hundreds of times, and the magnetic pressure on the projectile thousands of times. Similarly, with the help of a Bitter Magnet, pulsed magnetic fields with a density of thousands of Tesla are created.