A 0-D Electric Gun Model for the Optimization of Flyer Acceleration to Hypervelocities

Abstract

The electric gun is a pulsed power projectile launcher that utilizes the rapid expansion of an ohmically heated exploding foil and electromagnetic (EM) forces to accelerate thin flyers up to 20 km/s. Though the launcher has high energetic efficiencies when compared to alternative techniques, the process of launching flyers above 0.5 mm thickness in this manner often results in uncontrolled launch characteristics and premature failure of the flyer. This behavior is challenging to model numerically, limiting optimization work to sophisticated and computationally intensive magneto-hydrodynamics (MHD) codes. This work presents a 0-D model designed to expedite the parametric optimization process of electric gun loads to launch thick flyers to hypervelocities. The model is capable of predicting not only the foil state and flyer dynamics, but uses a novel approximation to predict the maximum pressure state in the flyer. The model is verified against 3-D MHD Eulerian hydrocode “Code $\mathbb{B}$ ” and the validity of the approximations made in simplifying the model are discussed. With this model, the electric gun could be optimized to launch thicker flyers and achieve higher pressures and shock durations, enabling it to become a complimentary tool to existing projectile launch platforms.