A Noninvasive Approach for Temperature Determination in Confined Cyclotol

Cyclotol is a melt-castable high explosive consisting of a mixture of RDX and TNT (75:25 wt. %). While used in conventional military applications, it can also be encountered in some types of IEDs (Improvised Explosive Devices). It is related to the more common Comp B (60:40 wt. %), and in the present work it was chosen as a case-study for noninvasive temperature determination in confined high explosives. An acoustics-based approach was used, based on (i) a collimated low-frequency acoustic beam, (ii) travel-time measurements of sound propagating along multiple paths, and (iii) sound speed-temperature inversion. Experiments were performed in a hermetically sealed cylindrical container with a volume of about 2 l, filled with casted Cyclotol. The container boundary temperature was varied between room temperature and ignition temperature. The experimentally determined acoustic temperature was in good agreement with other means of temperature measurements and finite-element modeling of temperature evolution in casted Cyclotol.