STARFIRE: hypervelocity railgun development for high-pressure research

STARFIRE has included efforts to identify and solve the problems that have inhibited reliable attainment of velocities greater than the 8 to 9 km/s attainable with two-stage light-gas guns (2SLGG). Issues studied include plasma arc formation and stabilization, restrike inhibition, viscous drag, ratio of preload to operating stresses, barrel joint design, and barrel precision requirements. The system uses a 2SLGG as an injector to minimize barrel ablation and armature contamination. Hydrogen is used as the injection gas and will also serve to reduce the probability of forming secondary arcs. An optical Doppler system is used to measure the projectile velocity continuously and precisely from a standing start in the 2SLGG barrel, through several joints, the HELEOS (hypervelocity experimental launcher for equation of state) railgun barrel, and postlaunch. The STARFIRE program is focused on the combined use of precision diagnostics and new experimental techniques. Test results are presented