Shock Compression Induced Hot Spots in Energetic Material Detected by Thermal Imaging Microscopy
Ming-Wei Chen, Sizhu You, Kenneth K. Suslick and Dana D. Dlott
6/17/2014
Introduction and Motivation (1)
pres
sure
time
P
“Show Highlights Science Behind Bat and Ball Collisions”, http://www.uml.edu/News/stories/2008-09/batlab_discovery_show.aspx
http://baseball.physics.illinois.edu/courtesy, Champaign News-Gazette and photographer Robin Scholtz, 2003
Introduction and Motivation (2)From a cold hammer to a fireball: How does it happen?
Cold EM
Mechanical Energy(Shock, impact, friction)
Warm EM
WithoutEnergy Concentrationprocess
No
deto
natio
n
WithEnergy Concentrationprocess
Exotherm
ic process
Loca
l hea
ting
http://www.bbc.co.uk/news/science-environment-11485672
Mechanical Energy
Chemical Energy
MWIR / Thermal Imaging
Sensor type: mercury cadmium telluride (MCT, >90% quantum efficiency)
Spectral response range: 3.7-4.8 µm.
Spatial resolution: <20 µm.
Frame speed: up to 120fps.
“Telescope orientation” “Microscope orientation”
High-speed MWIR camera
objective lenses
Object PC
Experimental Apparatus
Objective lens
High-speed MWIR camera
sample
glass
Al film glued on glassspacer
salt window
1064nm laser
8Al·MoO3
500μm
0 1000 2000 3000 4000 5000Bla
ck-b
ody
emis
sion
inte
nsity
(a.
u.)
Wavelength (nm)
Planck’s Law
1
125
2
TBkhc
e
hcTB
Visible NIR SWIR MWIR
Spectral response region of MWIR camera
0 1000 2000 3000 4000 5000Bla
ck-b
ody
emis
sion
inte
nsity
(a.
u.)
Wavelength (nm)
5273K 1273K 773K 673K 573K 473K 373K 273K
Shockwave Initiated Hot Spots in Thermite
IR image before experiment Thermal image taken during 200ns after impact
300K
717K
Salt window only
500μm
300K
729K
Shockwave Initiated Hot Spots in Sucrose
300K
745K
IR image before experiment Thermal image taken during 200ns after impact
300K
734K
500μm
Shockwave Initiated Hot Spots in Sucrose/HTPB
pellet
300K
685K
IR image before experiment Thermal image taken during 500ns after impact
500μmThickness ~100 μm
Shockwave Initiated Hot Spots in Sucrose/HTPB
pellet
300K
685K
IR image before experiment Thermal image taken during 500ns after impact
500μmThickness ~100 μm
Summary and Future Works
Summary Direct detection of hot spot initiated by shock impact appearing at around the
location of energetic particles has been demonstrated. Small explosive simulant (1-2mm dia. cross section) has been produced with
~100μm thickness, and tested with the experimental apparatus. Temperature rising rate is about the order of 109K/s within 200ns after impact.
Future Works Better thin sample preparation and fabrication procedure will be needed. Experiments with different composite materials, such as PBS, PBX. Varying
the size and density of particles to discover the energy localization under shock compression.
Acknowledgement• Dr. Dana D. Dlott• Dr. Kenneth S. Suslick• The Dlott research group• The Suslick research group• Funding:
– Office of Naval Research– Defense Threat Reduction Agency– National Science Foundation