First experimental results with the ISL 10 MJ DES railgun PEGASUS

A 10 MJ DES (distributed energy storage) railgun with 12 current inputs distributed along the 50 mm round bore launcher has been built at ISL. The power supply consists of 200 LCR pulse forming units of 50 kJ each. The 6 m long launcher tube containing the Cu-Cr rails is made of both wound glass fiber and wound carbon fiber reinforced plastic. This paper presents the facility and the first experimental results obtained by using projectiles made of Ti or equipped with metallic fiber-brush armatures. The triggering of the 12 DES stages is synchronized with the position of the projectile detected by B-dot probes located along the launcher tube. The currents delivered by the stages are measured by means of Rogowski coils surrounding the injection slots. The maximum total current reaches 2 MA resulting from the addition of the 12 current profiles of 800 kA delivered by each stage of the DES energy supply. The launcher has proved to have an overall efficiency of about 30%. Projectiles with masses ranging from 300 g to 650 g have been accelerated up to velocities of 2300 m/s. The quality of the electrical contact between rails and armature has been analyzed by electrical measurements and flash radiographs.