Affiliations: [a] Associate Professor, Department of Electrical
Engineering, Auburn University, AL, USA | [b] Department of Electrical Engineering and Computer
Science, US Military Academy, West Point, NY, USA | [c] Fuzes Branch (AFRL/MNMF), Eglin Air Force Base, FL,
USA
Abstract: A numerical investigation of the behavior of electrically thin
exploding foils is presented. This work examines the effect that non-linear
material properties have on the electrodynamic behavior of three metallic
bridgefoils (Al, Cu, Au) having identical geometries but different material
compositions. Previous experimental work and simulations focused on copper
bridgefoils electrically excited using the first quarter cycle of a 1200 A, 1.7
Mhz current source. This high power current pulse induced solid to vapor phase
transitions over the entire foil surface in exploding foil experiments. Use of
a finite element code (FEM) to determine the transient thermal and electrical
effects in the pre-melt regime has been previously demonstrated for copper. The
FEM code solves two non-linear partial differential equations which account for
the thermal conductivity, latent heat of fusion, and specific heat
(C_{\rm v}) of the foil. The focus of this research is to
contrast the simulated behavior of three metal foils (Al, Cu, Au) by examining
corresponding plots of electrical and thermal signatures as the foils progress
temporally to melt. The model predicts that the pattern of pre-melt behavior
for all three foils is similar. The time to melt was found to be shortest for
gold, followed by copper, and finally, aluminum (T_m {\rm Au}
< T_m {\rm Cu} < T_m{\rm Al}).
