Original Date: 05/17/1993
Revision Date: 01/18/2007
Information : Advances in Exploding Foil Initiator Technology
The Crane Division-Naval Surface Warfare Center is perfecting the use of an exploding foil initiator (EFI) to supply the explosive output for a handheld, battery powered firing device capable of initiating ordnance at a pre-programmed date and time. Use of EFI technology has greatly increased both the safety and reliability of such devices. In traditional firing devices, the explosive output is accomplished through the use of a lead azide detonator.
Due to the higher sensitivity of lead azide detonators, less firing energy is necessary for detonation, making devices more susceptible to premature detonation due to EMI and other environmental stresses. As a result, an out-of-line design is required for systems utilizing these types of detonators. Firing the EFI requires a high voltage pulse, achieved through a capacitor discharge, to be delivered to a foil trace on a PCB. This trace explodes, forcing a plastic flyer though a hole in an insulating separation disk and into an hexanitrostilbene (HNS) Type IV pellet. The shock wave generated by the plastic flyer initiates the HNS, a stable, low sensitivity explosive to begin the explosive train.
Due to the utilization of the stable HNS, the high detonation threshold voltage, and the overall safety of the design, the EFI detonator has been approved by the Weapon System Explosives Safety Review Board for use in- line systems. An in- line design eliminates the need for any moving components, thereby making the device inherently more reliable. While the cost of the initial developmental prototypes has been higher than the costs for traditional systems, the specification and certification of less expensive components as well as the production of these systems in greater quantities are expected to reduce costs substantially. Even at higher cost, the increased reliability and the substantial increase in safety make systems using EFI technology attractive for use in military and commercial applications.
For more information see the
Point of Contact for this survey.