Experimental launcher facility - ELF-I: Design and operation

The ELF-I system has recently become fully operational and the experimental program begun. This system uses a 36 kJ, 5 kV capacitor bank as a primary pulse power source. When used in conjunction with a 5 μH pulse conditioning coil, a 100 kA peak current and ∼10 ms wide pulse is obtained. The launcher barrel is 2 m long with a 12.7 mm square bore. With the launched mass in the range of 3 to 7 g velocities in excess of 1 km/s have been obtained. An extensive array of diagnostic instruments have been installed on the system to obtain measurements of current, breech and muzzle voltage, in-bore velocity profiles, and terminal velocity. Problems associated with electromagnetic interference and high common-mode voltages have been addressed and solved. A three station, 150 kV, flash x-ray system is operational for obtaining in-bore photographs of the projectiles. Details of the mechanical and electrical design and the instrumentation system will be presented. The experimental program, now underway, is directed towards obtaining information on armature-rail interactions at sliding velocities up to 1 km/s for both metallic and plasma armatures. One particular problem being addressed is that of current transfer in the breech where the sliding velocity is very low. Experimental results and their analysis are presented.