Preliminary discussion on the ignition mechanism of exploding foil initiators igniting boron potassium nitrate

Abstract

Exploding foil initiator (EFI) is a kind of advanced device for initiating explosives, but its function is unstable when it comes to directly igniting pyrotechnics. To solve the problem, this research aims to reveal the ignition mechanism of EFIs directly igniting pyrotechnics. An oscilloscope, a photon Doppler velocimetry, and a plasma spectrum measurement system were employed to obtain information of electric characteristics, impact pressure, and plasma temperature. The results of the electric characteristics and the impact pressure were inconsistent with ignition results. The only thing that the ignition success tests had in common was that their plasma all had a relatively long period of high-temperature duration (HTD). It eventually concludes that the ignition mechanism in this research is the micro-convection heat transfer rather than the shock initiation, which differs from that of exploding foil initiators detonating explosives. Furthermore, the methods for evaluating the ignition success of semiconductor bridge initiators are not entirely applicable to the tests mentioned in this paper. The HTD is the critical parameter for judging the ignition success, and it is influenced by two factors: the late time discharge and the energy of the electric explosion. The longer time of the late time discharge and the more energy of the electric explosion, the easier it is to expand the HTD, which improves the probability of the ignition success.