Simulation and Experimental Studies of Electrothermal Behaviors of Microwire Initiators for Fusing Applications

Microwire initiators enhance the output pressure and reduce the required input voltage for the explosives initiation in fusing applications due to large surface areas and high electrical and thermal conductivities. We investigated electrothermal behavior of Cu and Au microwires with diameters in the range of 25∼100 μm. Microwires with smaller diameter ignited quickly and required the lower input voltage to be ignited. A low impedance circuit was used in order to apply relatively low voltages but high current density to the initiator wire. We investigated the ignition process theoretically by combining an electric circuit model and a specific current action model related to phase changes. The theoretical calculations are in good agreement with the experimental observations in terms of the burst time and voltage rise profile.