Effects of thin metal outer case and top air gap on thermal IR images of buried antitank and antipersonnel land mines

A numerical simulation is carried out to study the effect of the thin metal outer case of an antitank mine and the top air gap of an antipersonnel mine on the passive infrared imaging signature. In addition, an antipersonnel surface mine is also analyzed in the present investigation to show its effect on the soil thermal content. The effect of short- and long-wavelength radiation as well as the convective heat transfer is incorporated in this analysis. The temporal development of the temperature distribution over a diurnal cycle is presented for both buried mines. The results show that the thin metal outer case of a buried antitank mine and the top air space of a buried antipersonnel mine have a pronounced effect on the depthwise temperature through the soil. Also, the results show that both buried mines have a noticeable effect on the intensity of the landmine signature on the soil-top surface over a diurnal cycle. A nonexisting mine signature on the soil-top surface is established for an antitank mine with a thin metal outer case. An almost nonexistent signature is also in evidence for the antipersonnel mine with or without an air gap. The results of the present investigation show that the thermal signature of a surface mine produces much larger temperature extremes than the thermal signature of a buried mine. These results play an important role in producing more effective techniques for mine imaging detection.