Superconducting augmented rail gun (SARG)

Superconducting augmentation consists of a superconducting coil operating in the persistent mode closely coupled magnetically with a normally conducting rail gun. A theoretical investigation of the effect of this system on a rail gun has shown that two benefits occur. Projectile velocities and launch efficiencies increase significantly depending on the magnetic coupling between the rail and augmentation circuits. The previous work [1] evaluated an idealized system by neglecting energy dissipation effects. In this paper, we extend the analysis to include the neglected terms and show improved actual launch efficiencies for the SARG configuration. To evaluate this concept, a one meter, 0.95 cm square bore rail gun powered by a 5 KV, 1440 µf capacitor discharging into a pulse shaping inductance of about 5µh was constructed. This system will accelerate a 4 g armature type projectile to the 0.8 km/sec range. Superconducting augmentation will be accomplished using a 4 Tesla dipole magnet recently acquired from DOE's Lawrence Berkeley Laboratory. This magnet system, originally designed as an ESCAR bending magnet, has been modified to a warm bore configuration operating in either the persistent or constant current mode powered by 1600 amp DC supplies. These modifications will allow the above rail gun to be inserted and tested in the SARG configuration. Several factors, including magnetic quench protection, reproducibility of results, relatively low magnetic coupling coefficients, minimazation of rail wear, etc., indicated that this experimental evaluation be conducted with an armature device. An advanced armature design is incorporated in our projectiles. In this paper, we will discuss these details in more depth and present preliminary results of rail gun performance.