Testing the EMP Effect on an Ordnance System

Published experimental work on the effect of electromagnetic pulse over the electro-explosive devices (EED) is scarce in the literature. The effect may be perceived in two different modes on the bridgewire type EEDs. One is the pin-to-pin mode and the other is the pin-to-case mode. In this work, the authors attempt to measure the pin-to-pin effect using the energy concept. An ordnance system comprising of passive elements was subjected to an electromagnetic pulse. A method is devised to measure the energy induced to the hot bridgewire type electro-explosive device. Briefly, the method is as follows: the components of the equipment under test was placed inside a GTEM cell. One end of the EED wire was brought to the outside of the GTEM cell. The induced current on the wire was pickud up by an RF current probe in the differential mode. The output of the current probe was sampled by a digitizing oscilloscope. The sampled time domain waveform was transformed to the frequency domain by applying FFT. Afterwards, the correction factors of the current probe was introduced. By using the frequency domain current components then obtained, the energy dissipated on the bridgewire resistance was calculated. The test results will be given in the paper. The validity of the applied method is to be discussed.