Microwave Ignition of Thermites

Abstract This study investigates the microwave ignition behavior of a range of thermites of aluminum, boron, titanium, and tantalum fuels with oxides of Bi 2 O 3 , CuO, and Fe 2 O 3 . In order to gain insight into the modes of energy transfer leading to ignition, thermites are heated in either a purely electric or magnetic field environment within a single‐mode 2.45 GHz resonant cavity with electric field strengths of 40 to 110 kV/m and magnetic field strengths of 22 to 258 A/m. Thermite stoichiometry is varied as well as particle size and thermite mass. The shortest ignition delays in electric and magnetic fields were found to be 1.37 s (nAl and CuO) and 0.87 s (nAl and CuO), respectively. The use of a variety of carbon susceptors to shorten ignition delay is also studied. Carbon susceptors are found to appreciably shorten ignition delays to as short as 140 and 170 ms for the E and B field respectively (nAl and CuO with multiwalled carbon nanotubes). The results of this work are informative on thermite component choice and the preferred mechanism (electric vs magnetic field) of heating for various thermite compositions for consideration of the increasingly popular ignition via electromagnetic fields.