DES 3 MJ-railgun experimental results at ISL

A capacitor bank, consisting of two stages, is used for experiments with a 50 mm round bore railgun at a maximum current of 2 MA. The railgun is fed at two different points in order to test the DES-railgun concept. An appropriate design and material choice of metallic projectiles, accelerated from the rest position, allow the current to be injected at the front side and to be distributed over the whole armature. It is shown that the contact between rails and projectile is maintained with a dominant metallic value and transitioning to plasma arcs has been seen only during short time intervals. Accurate voltage and current measurements allow evaluating of the ohmic losses and energy partition in the whole system. Measured values of rail resistance and inductance gradient are presented and compared to numerical simulations. The results of several shots are presented and compared to theoretical predictions, For a stored energy of 1.96 MJ, an overall efficiency of 21% is obtained with a projectile mass of 437 g accelerated to a velocity of 1370 m/s.<>