Failure Characteristics of Electro-Explosive Devices in Strong Magnetic Fields During Electromagnetic Launch

Strong pulsed magnetic fields generated during electromagnetic launch may couple energy into electro-explosive devices (EEDs) and cause inadvertent ignition. This study investigates the response of a bridge wire electric igniter under isolated and circuit-connected conditions using electrothermal modeling, finite element simulations, and pulsed magnetic field loading experiments. The results show that the magnetic field has only a weak direct effect on the tested isolated bridge wire igniter configuration, causing neither inadvertent ignition nor observable changes in appearance or bridge wire resistance under the investigated conditions. In contrast, circuit coupling markedly increased the ignition risk. The lowest tested equivalent coupling area that produced ignition was 240 mm2, with an average coupled energy of approximately 220.85 μJ, which is substantially lower than the 50% firing energy of 1893 μJ under conventional electrical excitation. The results further indicate that inadvertent ignition depends not only on the accumulated coupled energy but also on the electromagnetic energy-deposition rate.