Electromagnetic Modeling of Hot-Wire Detonators

An effort is underway to determine the electromagnetic (EM) characteristics of hot-wire detonators in order to quantify more precisely how they might respond to modern EM illumination. These analyses provide a precise tailored approach to EM safety and insights into IEEE Standard C95.7-2005. The analyses include a comprehensive investigation of physical detonator characteristics, which is then used to model detonators using EM theory. The theoretical analysis treats the detonator as a cascaded transmission line incorporating several different dielectric regions, and examines both differential and common mode excitation for a generic detonator geometry. This model is then implemented in MATLAB and is used to calculate the input impedance for the detonator from dc to 9 GHz. This program can then be used to quickly investigate similarly constructed hot-wire detonators by simply varying the input parameters. The model is used to predict the input impedance for a state-of-the-art blasting cap, and these predictions are then compared with experimental measurements.