Jared C. Gump

Isothermal equations of state of beta octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine at high temperatures

Isothermal pressure-volume equations of state of beta HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) at temperatures of 30, 100, and 140°C under both hydrostatic and nonhydrostatic compressions have been obtained using synchrotron angle-dispersive x-ray diffraction experiments. The samples were heated to the isotherm temperature and compressed up to 5.8GPa. At all temperatures HMX remained in the beta phase up to 5.8GPa. However, at 140°C upon decompression to ambient from nonhydrostatic pressures above 4GPa, HMX underwent a phase transition to the delta phase. The same transition was seen upon decompression to ambient from hydrostatic compression; however, parts of the sample remain in the β phase, resulting in a mixed-phase sample. The diffraction data were analyzed to yield unit-cell dimensions at each pressure, and further analyzed to yield thermal expansion, bulk modulus, and the pressure derivative of the bulk modulus.

Time-resolved optical measurements of the post-detonation combustion of aluminized explosives

The dynamic observation and characterization of light emission following the detonation and subsequent combustion of an aluminized explosive is described. The temporal, spatial, and spectral specificity of the light emission are achieved using a combination of optical diagnostics. Aluminum and aluminum monoxide emission peaks are monitored as a function of time and space using streak camera based spectroscopy in a number of light collection configurations. Peak areas of selected aluminum containing species are tracked as a function of time to ascertain the relative kinetics (growth and decay of emitting species) during the energetic event. At the chosen streak camera sensitivity, aluminum emission is observed for 10μs following the detonation of a confined 20g charge of PBXN-113, while aluminum monoxide emission persists longer than 20μs. A broadband optical emission gauge, shock velocity gauge, and fast digital framing camera are used as supplemental optical diagnostics. In-line, collimated detection is ...

Phase transitions and isothermal equations of state of epsilon hexanitrohexaazaisowurtzitane (CL-20)

The phase stability of epsilon hexanitrohexaazaisowurtzitane at high pressure and temperature was investigated using synchrotron angle-dispersive x-ray diffraction experiments. The samples were compressed at room temperature using a Merrill–Bassett diamond anvil cell. For high-temperature compression experiments a hydrothermal diamond anvil cell developed by Bassett was used. Pressures and temperatures of around 5 GPa and 175 °C, respectively, were achieved. The epsilon phase was determined to be stable under ambient pressure to a temperature of 120 °C. A phase transition to the gamma phase was seen at 125 °C and the gamma phase remained stable until thermal decomposition above 150 °C. Pressure-volume data for the epsilon phase at ambient and 75 °C were fitted to the Birch–Murnaghan formalism to obtain isothermal equations of state.

Equations of state of 2,6-diamino-3,5-dinitropyrazine-1-oxide

2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) is an energetic ingredient that has an impact sensitivity close to that of TATB, yet a calculated energy content close to HMX. Reported tests of formulated LLM-105 reveal that it is a good candidate for a new insensitive high-performance explosive. As use of LLM-105 increases, thermodynamic parameters and phase stability will need to be determined for accurate modeling. In order to accomplish this goal, isothermal equations of state of LLM-105 at static high-pressure and temperature were investigated using synchrotron angle-dispersive x-ray diffraction and diamond anvil cells. Data at ambient temperature, 100 °C (373 K), and 180 °C (453 K) were used to obtain isothermal equations of state, and data at ambient pressure were used to obtain the volume thermal expansion coefficient. At ambient temperature, 100 °C (373 K), and 180 °C (453 K) no phase change was evident up to the highest measured pressure; and at ambient pressure, LLM-105 was stable up to 240 °C (513 K) and thermally decomposed by 260 °C (533 K).

Atmospheric Effects on the Combustion of Detonating Aluminized Explosives

The detonation and subsequent combustion of aluminized explosive formulations depend heavily on the oxidation reactions of aluminum. Fuel‐rich formulations require oxygen from an external source (nominally an oxygen‐containing atmosphere or detonation products) to burn the fuel to completion. Dynamic spectroscopic measurements are made for an aluminized explosive (PBXIH‐135) to investigate the effect of changing atmospheres on the combustion properties of aluminum. The explosive formulation is tested under normal atmospheric conditions and in an atmosphere of nitrogen. Light emission (from 350–550 nm) from the explosive event is collected in a spectrometer and dispersed temporally in a streak camera. Aluminum emission (centered at 396 nm) is commonly observed in each atmosphere although the emission persists longer in nitrogen. Aluminum nitride (AlN) is observed as an intermediate in the oxidation of aluminum when oxygen is removed from the atmosphere. New, nitrogen‐containing species (near 387 and 418 nm...

Phase stability of {epsilon} and {gamma} HNIW (CL-20) at high-pressure and temperature

Hexanitrohexaazaisowurtzitane (CL‐20) is one of the few ingredients developed since World War II to be considered for transition to military use. Five polymorphs have been identified for CL‐20 by FTIR measurements (α, β, γ, e, ζ). As CL‐20 is transitioned into munitions it will become necessary to predict its response under conditions of detonation, for performance evaluation. Such predictive modeling requires a phase diagram and basic thermodynamic properties of the various phases at high pressure and temperature. Therefore, the epsilon and gamma phases of CL‐20 at static high‐pressure and temperature were investigated using synchrotron angle‐dispersive x‐ray diffraction experiments. The samples were compressed and heated using diamond anvil cells (DAC). Pressures and temperatures achieved were around 5 GPa and 240 °C, respectively. The epsilon phase was stable to 6.3 GPa at ambient temperature. When heated at ambient pressure the epsilon phase was sustained to a temperature of 120 °C then underwent a tr...

High‐Pressure Structural Study of Epsilon HNIW (CL‐20)

The structure of epsilon CL‐20 at room temperature was investigated using synchrotron angle‐dispersive x‐ray diffraction experiments and Raman spectroscopy. For x‐ray diffraction, the samples were compressed up to 6.3 GPa using a Merrill‐Bassett diamond anvil cell (DAC) under both hydrostatic and non‐hydrostatic conditions. Pressure — volume data were then fit to the Birch‐Murnaghan equation of state to obtain an isothermal equation of state. No phase transition was observed within this pressure range.Raman spectroscopy was performed in the range of 50–1650 cm−1. The samples were compressed non‐hydrostatically to 7.1 GPa. Changes in peak positions with increasing pressure were observed. Vibrational spectra were calculated using Hartree‐Fock and density functional theory and a comparison was made with the experimental spectrum.

Equations of state of hexanitrostilbene (HNS)

Hexanitrostilbene (HNS) is an energetic ingredient that is widely used in commercial and military explosives for its thermal stability. However, characterization of its thermodynamic parameters and phase stability is lacking. Crystalline properties, such as bulk modulus and thermal expansion, are necessary to accurately predict the behavior of shocked solids using hydrodynamic codes. In order to obtain these values, equations of state of fine-particle (type IV) HNS were investigated using synchrotron angle-dispersive x-ray diffraction experiments at static high-pressure and temperature. The samples were compressed and heated using diamond anvil cells. Pressure - volume data for HNS at ambient temperature were fit to the Birch-Murnaghan and Vinet formalisms to obtain bulk modulus and its first pressure derivative. Temperature - volume data at ambient pressure were fit to obtain the volume thermal expansion coefficient.

ISOTHERMAL EQUATIONS OF STATE OF LLM‐105

2,6‐diamino‐3,5‐dinitropyrazine‐1‐oxide (LLM‐105) is an energetic ingredient that has an impact sensitivity close to that of TATB, yet a calculated energy content close to HMX. Reported tests of formulated LLM‐105 reveal that it is a good candidate for a new insensitive high‐performance explosive. As use of LLM‐105 increases, thermodynamic parameters and phase stability will need to be determined for accurate modeling. In order to accomplish this goal, isothermal equations of state of LLM‐105 at static high‐pressure and temperature were investigated using synchrotron angle‐dispersive x‐ray diffraction experiments. The samples were compressed and heated using diamond anvil cells. Pressure—volume data for LLM‐105 at ambient temperature and 100° C were fit to the Birch‐Murnaghan formalism to obtain isothermal equations of state. Temperature—volume data at ambient pressure were fit to obtain the volume thermal expansion coefficient.

Modeling compressive reaction and estimating model uncertainty in shock loaded porous samples of hexanitrostilbene (HNS)

Neat pressings of HNS powders have been used in many explosive applications for over 50 years. However, characterization of its crystalline properties has lagged that of other explosives, and the solid stress has been inferred from impact experiments or estimated from mercury porosimetry. This lack of knowledge of the precise crystalline isotherm can contribute to large model uncertainty in the reacted response of pellets to shock impact. At high impact stresses, deflagration-to-detonation transition (DDT) processes initiated by compressive reaction have been interpreted from velocity interferometry at the surface of distended HNS-FP pellets. In particular, the Baer-Nunziato multiphase model in CTH, Sandias Eulerian, finite volume shock propagation code, was used to predict compressive waves in pellets having approximately a 60% theoretical maximum density (TMD). These calculations were repeated with newly acquired isothermal compression measurements of fineparticle HNS using diamond anvil cells to compr...