TY - JOUR
T1 - Hot spot generation in energetic materials created by long-wavelength infrared radiation
AU - Chen, Ming Wei
AU - You, Sizhu
AU - Suslick, Kenneth S
AU - Dlott, Dana D.
N1 - Publisher Copyright:
© 2014 AIP Publishing LLC.
PY - 2014/10/2
Y1 - 2014/10/2
N2 - Hot spots produced by long-wavelength infrared (LWIR) radiation in an energetic material, crystalline RDX (1,3,5-trinitroperhydro-1,3,5-triazine), were studied by thermal-imaging microscopy. The LWIR source was a CO2 laser operating in the 28-30THz range. Hot spot generation was studied using relatively low intensity (∼100W cm-2), long-duration (450 ms) LWIR pulses. The hot spots could be produced repeatedly in individual RDX crystals, to investigate the fundamental mechanisms of hot spot generation by LWIR, since the peak hot-spot temperatures were kept to ∼30K above ambient. Hot spots were generated preferentially beneath RDX crystal planes making oblique angles with the LWIR beam. Surprisingly, hot spots were more prominent when the LWIR wavelength was tuned to be weakly absorbed (absorption depth ∼30μm) than when the LWIR wavelength was strongly absorbed (absorption depth ∼5μm). This unexpected effect was explained using a model that accounts for LWIR refraction and RDX thermal conduction. The weakly absorbed LWIR is slightly focused underneath the oblique crystal planes, and it penetrates the RDX crystals more deeply, increasing the likelihood of irradiating RDX defect inclusions that are able to strongly absorb or internally focus the LWIR beam.
AB - Hot spots produced by long-wavelength infrared (LWIR) radiation in an energetic material, crystalline RDX (1,3,5-trinitroperhydro-1,3,5-triazine), were studied by thermal-imaging microscopy. The LWIR source was a CO2 laser operating in the 28-30THz range. Hot spot generation was studied using relatively low intensity (∼100W cm-2), long-duration (450 ms) LWIR pulses. The hot spots could be produced repeatedly in individual RDX crystals, to investigate the fundamental mechanisms of hot spot generation by LWIR, since the peak hot-spot temperatures were kept to ∼30K above ambient. Hot spots were generated preferentially beneath RDX crystal planes making oblique angles with the LWIR beam. Surprisingly, hot spots were more prominent when the LWIR wavelength was tuned to be weakly absorbed (absorption depth ∼30μm) than when the LWIR wavelength was strongly absorbed (absorption depth ∼5μm). This unexpected effect was explained using a model that accounts for LWIR refraction and RDX thermal conduction. The weakly absorbed LWIR is slightly focused underneath the oblique crystal planes, and it penetrates the RDX crystals more deeply, increasing the likelihood of irradiating RDX defect inclusions that are able to strongly absorb or internally focus the LWIR beam.
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U2 - 10.1063/1.4865258
DO - 10.1063/1.4865258
M3 - Article
AN - SCOPUS:84912080169
VL - 104
JO - Applied Physics Letters
JF - Applied Physics Letters
SN - 0003-6951
IS - 6
M1 - 061907
ER -