The committee's assessment of the present state of thermobarics research and testing in the United States is that it is relatively immature and not particularly well structured.a As discussed further below, the committee believes that this is a result of the following: • The speed with which the United States attempted to field a thermobaric munition clone for use in Afghanistan; • The inability and reluctance of the services to field new materials (hence, the redefinition of thermobarics to include Indian Head Explosive 135 [IH-135]); • The unclear definition of terms; • The lack of careful analysis and experimentation; • Inadequate diagnostics that have perpetuated the reliance on anecdotal evidence as opposed to data; and • Testing against varied types of targets and unclear scale effects.

31. Advanced Energetic Materials
THERMOBARIC EXPLOSIVES 17
While the Russian military identifies its weapons systems as thermobarics, the Russian
scientific community refers to these materials as low-density explosives, or metallized
volumetric explosives. Studies of thermobaric systems in the West date to about 1988 and
were driven primarily by interest from the intelligence communities and by efforts to exploit
foreign technology. A working definition of the term evolved, defining the thermobaric
weapon as a single-cycle, fuel-rich explosive system that has a long-duration thermal pulse
accompanying and supporting shock output. The term "thermobaric" now appears to be
synonymous with fuel-rich or enhanced-blast explosives.
Current thermobaric munitions have been purported to exploit secondary combustion
as a source of lethal energy and as effectively providing increased internal blast energy when
deployed against soft targets such as buildings and against personnel and equipment inside
confined targets, including tunnels and caves. Whether or not the extra combustion energy
enhances the lethality of a munition depends on how the extra energy couples with the
target. Energy that does not contribute to the detonation (shock) regime may still prove
lethal if it can add to the total impulse within 10s of milliseconds inside a building or up to a
second within a tunnel.7 Further, the addition of materials that increase the density of the
fireball may improve the coupling between it and the target, which can provide additional
effectiveness. While extensive modeling studies are currently under way, few if any of these
phenomena are well understood in the context of a thermobaric explosive application.
Careful trade-off studies that examine the contributions of these effects are necessary for
their successful implementation.
The committee's assessment of the present state of thermobarics research and
testing in the United States is that it is relatively immature and not particularly well
structured.a As discussed further below, the committee believes that this is a result of the
following:
• The speed with which the United States attempted to field a thermobaric munition
clone for use in Afghanistan;
• The inability and reluctance of the services to field new materials (hence, the
redefinition of thermobarics to include Indian Head Explosive 135 [IH-135]);
• The unclear definition of terms;
• The lack of careful analysis and experimentation;
• Inadequate diagnostics that have perpetuated the reliance on anecdotal evidence
as opposed to data; and
• Testing against varied types of targets and unclear scale effects.
An advanced concept technology demonstration (ACTD) effort was initiated by the
Defense Threat Reduction Agency in 2001. It was to be a 3-year program. Driven by media
reports from Chechnya and in the aftermath of September 11, 2001, the DoD and DTRA
diverged from the original plan and embarked on an ambitious, 60-day ACTD program to
demonstrate a thermobaric weapon in Afghanistan. The materials studied were conventional
high explosives that included some of the features seen in Russian thermobaric systems,
which utilized fuel-rich, heavily metallized, minimally confined explosive fills.
In contrast to the recent U.S. effort, much of the work done on thermobarics by others
outside the United States focused on direct experimentation, some of which was quite
sophisticated and dealt directly, although empirically, with the difficulty in measuring the
performance of particular explosive devices. In the aforementioned presentations to the
committee, evidence showed that the performance of this type of thermobaric explosive is
7 H. Shechter, OSU. 2001. Synthesis of 1,2,3,4-Tetrazines Di-N-Oxides, Pentazole Derivatives, and
Pentazine Poly-N-Oxides. Presentation to the committee. December 13.
s K. Kim, DTRA. 2001. Presentation to the committee. July 31.
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