Microwave radiation from combustion of an iron-aluminum thermite mixture

Nonequilibrium microwave radiation from the combustion wave of the Fe$_2$O$_3$–Al powder system in the frequency range of 3.4–37.5 GHz was recorded. It is found that the radiation power is proportional to the free-surface area of the reaction products and is 4–7 orders of magnitude higher than the thermal-radiation level in the same wavelength interval. A possible mechanism of the electromagnetic emission is the Bremsstrahlung of the mobile electrons released by the condensed-phase surface.