We consider the energy accumulation in meta-stable clusters. This energy can be much larger than the typical chemical bond energy (~;;1 ev/atom). For example, polymeric nitrogen can accumulate 4 ev/atom in the N8 (fcc) structure, while helium can accumulate 9 ev/atom in the excited triplet state He2* . They release their energy by cluster fission: N8 -> 4N2 and He2* -> 2He. We study the locus of states in thermodynamic state space for the detonation of such meta-stable clusters. In particular, the equilibrium isentrope, starting at the Chapman-Jouguet state, and expanding down to 1 atmosphere was calculated with the Cheetah code. Large detonation pressures (3 and 16 Mbar), temperatures (12 and 34 kilo-K) and velocities (20 and 43 km/s) are a consequence of the large heats of detonation (6.6 and 50 kilo-cal/g) for nitrogen and helium clusters respectively. If such meta-stable clusters could be synthesized, they offer the potential for large increases in the energy density of materials.

Successfully attacking underground storage facilities for chemical and biological (C/B) weapons is an important mission area for the Department of Defense. The fate of a C/B agent during an attack depends critically on the pressure and thermal environment that the agent experiences. The initial environment is determined by the blast wave from an explosive device. The byproducts of the detonation provide a fuel source that burn when mixed with oxidizer (after burning). Additional energy can be released by the ignition of the C/B agent as it mixes with the explosion products and the air in the chamber. Hot plumes venting material from any openings in the chamber can provide fuel for additional energy release when mixed with additional oxidizer. Assessment of the effectiveness of current explosives as well as the development of new explosive systems requires a detailed understanding of all of these modes of energy release. Using methodologies based on the use of higher-order Godunov schemes combined with Adaptive Mesh Refinement (AMR), implemented in aparallel adaptive framework suited to the massively parallel computer systems provided by the DOD High-Performance Computing Modernization program, we use a suite of programs to develop predictive models forthe simulation of the energetics of blast waves, deflagration waves and ejecta plumes. The programs use realistic reaction kinetic and thermodynamic models provided by standard components (such as CHEMKIN) as well as other novel methods to model enhanced explosive devices. The work described here focuses on the validation of these models against a series of bomb calorimetry experiments performed at the Ernst-Mach Institute. In this paper, we present three-dimensional simulations of the experiments, examining the explosion dynamics and the role of subsequent burning on the explosion products on the thermal and pressure environment within the calorimeter. The effects of burning are quantified by comparing two sets of computations, one in which the calorimeter is filled with nitrogen so there is no after burning and a second in which the calorimeter contains air.