Multi-turn railguns: concept analysis and experimental results

The multi-rail concept of railguns, the so-called multi-turn railguns, has been considered and dependences of their main parameters such as accelerating force, current density distribution in rails and breech voltage upon bore sizes, number of turns and the launcher´s scale are presented. The experimental designs of multi-turn railguns built in the TRINITI in 1995-1999 are described: a three-turn RBM-3-1 and MTR-3-1.3 railgun with a 5.6 μH/m inductance gradient and two five-turn RBM-5-05 and RBM-5-2 railguns with 0.5 m and 2 m bore length, correspondingly and a 16.5 μH/m inductance gradient both. The experimental design of the armature for these railguns is described as well. The results of tests of launching armatures with a 0.14-1.1 kg mass up to velocities of 800-1300 m/s and accelerations up to 8·10⁵ m/s² are given. Representative oscillograms of current and muzzle voltage of each rail pair are shown. Some methods of providing electrical strength for rail insulation in the bore and armature plates at metal contact fault are considered. Strengths and weaknesses of multi-turn launchers in comparison with conventional ones are discussed and an advantage of the former railguns at launching bodies with large volume and mass is shown