A Study of Electrothermal-Launcher Efficiencies and Gas Dynamics

This paper describes a series of experiments to study the efficiency of an electrothermal (ET) launcher. The launcher serves as a preaccelerator for a plasma-driven hypervelocity railgun experiment at the Institute for Advanced Technology. The ET launcher is designed to accelerate small polycarbonate projectiles to about 1 km/s. The objective of this paper was to understand how pulse duration affects the efficiency with which the pressure of the ET discharge is coupled to the projectile. This paper consisted of multiple tests for which the total energy of the discharge was kept constant, but the pulselength was varied. The dependent variable in the tests was the muzzle velocity of the projectile. The experimental results are presented and compared with gas-dynamic considerations.