Scaling relationships for plasma driven railguns

Results from experiments on the derivation of a scaling relationship for the voltage drop measured across a plasma armature (muzzle voltage) in an electromagnetic launcher are presented. Data taken from over 300 test firings in the two LTV electromagnetic launchers indicate an empirical relationship between the muzzle voltage (M_V) and the product of the plasma pressure (p ) and bore separation (d) given by M_V= a(pd)^b. This scaling relationship has been incorporated into a computer model that contains the Los Alamos National Laboratory (LANL) ablation model to determine the ultimate velocity achievable from LTVs and other railguns. These predictions are then compared specifically with the measured mass versus velocity data obtained from the 20-mm DES (distributed energy source) railgun. Results of tests using different insulating materials (glass-reinforced polyester and a polyamide-imide material) are presented to show the effects of different ablation rates on the railgun efficiency and limiting railgun velocity