Characterization of the super-short shock pulse generated by an exploding foil initiator

Abstract

Exploding foil initiator (EFI) uses a thin flyer to initiate an explosive pellet. The shock pulse generated by EFI is very difficult to measure and calculate accurately, which is crucial to the operation of EFI. The velocity of the thin flyer driving by electrical explosion was obtained in order to quantitate the input of the impact process. Replacing the explosive pellet by a LiF window, the super-short shock pulse generated by a thin flyer (25 μm) was measured using the interface particle velocity method by a Photonic Doppler Velocimetry (PDV). The maximum particle velocity is 1.716 km/s in the experimental condition, meanwhile the shock duration is 4.5 ns. The impedance matching technique and the shock Hugoniot data were used to calculate the shock pressure and shock duration of the impact process, however the calculation results have distinct error comparing to the experimental ones. Utilizing the elastic-plastic model of flyer which considers the kinematic hardening plasticity effect, the simulations were carried out to predict the particle velocity and shock duration. The results show good consistency of the experimental and simulated particle velocities, which infers that the material model of flyer can describe its impact behaviours accurately.