Initiation of some energetic materials by microwave heating

Microwave heating of ammonium nitrate (AN), tetryl, PETN, RDX, HMX, TNT, emulsion explosive, Composition C-4, and ammonium perchlorate (AP) was carried out at the frequency of 2450 + 50 MHz. The energetic materials were confined in sodalime glass tubes with teflon and silicon rubber plugs. The order of increasing initiation delay time was AN, tetryl, PETN, RDX, HMX, and TNT. Also, the order of the initiation energy of energetic materials was the same when the anode currents of microwave power source were 1.1 A and 0.8 A. The initiation processes of energetic materials were recorded on videotapes which showed that the energetic materials gencrally melted before initiation. The temperatures of energctic matcrials were measured by K-type (chromel-alumel) thermocouples and an infrared thermometer. The temperature of each energetic material started to rise rapidly when the temperature neared the meiting point. Initiation occured near the ignition temperature with a delay varying from 6 to 109 seconds.