Richard L. Gustavsen

Calibration of the ruby R1 and R2 fluorescence shifts as a function of temperature from 0 to 600 K

Recent work by Gupta and Shen [Appl. Phys Lett. 58, 583 (1991)] has shown that in a nonhydrostatic environment, the frequency of the ruby R2 line provides a reliable measure of the mean stress or pressure. When using the frequency of either the R1 or R2 line to measure pressure at nonambient temperature, it is necessary to know the temperature dependence of the line shift. Unfortunately, the shift of the R2 line with temperature has not been reported. The ruby R1 and R2 fluorescence shifts have been determined as a function of temperature from 15 to 600 K. Both can be fitted very well to the simple cubic forms R1(T) =14 423+4.49×10−2T−4.81×10−4T2+3.71×10−7T3 cm−1 and R2(T)=14 452 +3.00×10−2T−3.88×10−4T2+2.55×10−7T3 cm−1. From 300 to 600 K the shifts fit well to linear functions of temperature. In addition, it is found that the R1‐R2 splitting changes by about 3 cm−1 over the 600 K temperature range. Linewidths were found to vary both with temperature and from sample to sample.

Initiation of EDC-37 measured with embedded electromagnetic particle velocity gauges

Planar shock wave initiation of the explosive EDC-37 was studied using multiple embedded magnetic particle velocity gauges. EDC-37 consists of (by weight) 91% HMX, 1% nitrocellulose, and 8% K10, a liquid eutectic mixture of di-nitro-ethyl-benzene and tri-nitro-ethyl-benzene. Its nominal density is 1.841±0.002 g/cm3. The Hugoniot for EDC-37 was measured as US=2.4+2.4uP, similar to other explosives of this density containing at least 90% HMX. The run distance to detonation, X*, vs. shock pressure P, was measured as log(X*)=2.0−1.5 log(P). This curve is shifted to a few GPa higher pressure compared to that of other plastic bonded explosives containing 90–95% HMX. This shift is most likely due to the low void content of EDC-37. Like other high density HMX based explosives, EDC-37 initiates with wave profiles having a little increase in particle velocity at the shock front (heterogeneous initiation), and also a second wave which starts small at the impact surface, grows as it travels, and reaches a large ampli...

Reactive, anomalous compression in shocked polyurethane foams

We present the results of plate impact experiments performed on 30%–75% porous, polymeric methylene diphenyl diisocyanate polyurethane foams. The combination of new data with those previously obtained on full-density material was used to calibrate complete equations-of-state under both inert and chemically reactive frameworks. Description of unreacted polyurethane was based on a combination of Hayes and P-α models, whereas its decomposition products were predicted via free energy minimization under the assumption of chemical and thermodynamic equilibrium. Correspondence of experiment and theory suggests that polyurethane at all densities decomposes when shocked above some threshold pressure, and that this threshold falls dramatically as a function of initial porosity. The shock locus of foams at 50% or less of theoretical maximum density was found “anomalous” in the sense that final volumes increased with pressure. We attribute this anomaly to chemical decomposition of the initial matrix to a mixture of s...

Shock initiation of the tri-amino-tri-nitro-benzene based explosive PBX 9502 cooled to −55 °C

We report a series of shock initiation experiments on PBX 9502 cooled to −55 °C. PBX 9502 consists of 95% dry aminated tri-amino-tri-nitro-benzene (TATB) and 5% poly-chloro-trifluoro-ethylene5 (Kel-F 800) binder. PBX 9502 samples were shock initiated by projectile impact from a two stage gas gun. Buildup to detonation was measured with 10 or more particle velocity gauges embedded at different depths in the sample. Three shock wave trackers measured the position of the shock front with time. Particle velocity vs. time wave-profiles and coordinates for onset of detonation were obtained as a function of the impact stress or pressure. PBX 9502 sample temperatures were monitored using type-E thermocouples, two inside the sample and two on the sample surface. Additional thermocouples were mounted on other parts of the cooling apparatus. Wave profiles from embedded gauges are qualitatively similar to those observed at 23 °C. However, at −55 °C, PBX 9502 is much less sensitive than at 23 °C. For example, at an inpact stress of 15.4 GPa, the distance to detonation at −55 °C is 7.8 mm. At 23 °C, the distance is 4.3 mm.

Time resolved small angle X-ray scattering experiments performed on detonating explosives at the advanced photon source: Calculation of the time and distance between the detonation front and the x-ray beam

Time resolved Small Angle X-ray Scattering (SAXS) experiments on detonating explosives have been conducted at Argonne National Laboratorys Advanced Photon Source Dynamic Compression Sector. The purpose of the experiments is to measure the SAXS patterns at tens of ns to a few μs behind the detonation front. Corresponding positions behind the detonation front are of order 0.1–10 mm. From the scattering patterns, properties of the explosive products relative to the time behind the detonation front can be inferred. This report describes how the time and distance from the x-ray probe location to the detonation front is calculated, as well as the uncertainties and sources of uncertainty associated with the calculated times and distances.

One-dimensional plate impact experiments on the cyclotetramethylene tetranitramine (HMX) based explosive EDC32

Eight one-dimensional plate impact experiments have been performed to study both the Shock to Detonation Transition and Hugoniot state in the cyclotetramethylene tetranitramine (HMX) based explosive EDC32. The experiments covered shock pressures ranging from 0.59 to 7.5 GPa with sustained shocks, double shocks, and short pulse shocks. Experiments were instrumented with embedded magnetic particle velocity gauges. Results include; (1) wave profiles of particle velocity vs. time vs. depth in the explosive, (2) time-distance coordinates for onset of detonation vs. initial shock pressure (aka the Pop-plot), (3) a reactants Hugoniot, and (4) measurement of the Hugoniot Elastic Limit of 0.22.GPa.

Structural evolution of detonation carbon in composition B by X-ray scattering

Products evolved during the detonation of high explosives are primarily a collection of molecular gases and solid carbon condensates. Electron microscopy studies have revealed that detonation carbon (soot) can contain a variety of unique carbon particles possessing novel morphologies, such as carbon onions and ribbons. Despite these observations very little is known about the conditions that leads to the production of these novel carbon nanoparticles. A fuller understanding on conditions that generate such nanoparticles would greatly benefit from time-resolved studies that probe particle formation and evolution through and beyond the chemical reaction zone. Herein, we report initial results employing time-resolved X-ray scattering (TRSAXS) measurements to monitor nanosecond time-scale carbon products formed from detonating Composition B (60% TNT, 40% RDX). These studies were performed at the Dynamic Compression Sector (DCS, Sector 35) at the Advanced Photon Source (Argonne National Laboratory). Analysis o...

An equation of state for polymethylpentene (TPX) including multi-shock response

The equation of state (EOS) of polymethylpentene (TPX) is examined through both single shock Hugoniot data as well as more recent multi-shock compression and release experiments. Results from the recent multi-shock experiments on LANLs two-stage gas gun will be presented. A simple conservative Lagrangian numerical scheme utilizing total variation diminishing interpolation and an approximate Riemann solver will be presented as well as the methodology of calibration. It is shown that a simple Mie-Gruneisen EOS based on a Keane fitting form for the isentrope can replicate both the single shock and multi-shock experiments.

EXPERIMENTAL MEASUREMENTS OF THE CHEMICAL REACTION ZONE OF DETONATING LIQUID EXPLOSIVES

We have a joint project between CEA‐DAM Le Ripault and Los Alamos National Laboratory (LANL) to study the chemical reaction zone in detonating high explosives using several different laser velocimetry techniques. The short temporal duration of the von Neumann spike and early part of the reaction zone make these measurements difficult. Here, we report results obtained from detonation experiments using VISAR (velocity interferometer system for any reflector) and PDV (photon Doppler velocimetry) methods to measure the particle velocity history at a detonating nitromethane/PMMA interface. Experiments done at CEA were high‐explosive‐plane‐wave initiated and those at LANL were gas‐gun‐projectile initiated with a detonation run of about 6 charge diameters in all experiments. The experiments had either glass or brass confinement. Excellent agreement of the interface particle velocity measurements at both Laboratories were obtained even though the initiation methods and the velocimetry systems were somewhat differ...

Characterization of detonation soot produced during steady and overdriven conditions for three high explosive formulations

The detonation of high explosives (HE) produces a dense fluid of molecular gases and solid carbon. The solid detonation carbon contains various carbon allotropes such as detonation nanodiamonds, onion-like carbon, graphite and amorphous carbon, with the formation of the different forms dependent upon pressure, temperature and the environmental conditions of the detonation. We have collected solid carbon residues from controlled detonations of three HE formulations (Composition B-3, PBX 9501, and PBX 9502). Soot was collected from experiments designed to produce both steady and overdriven conditions, and from detonations in both an ambient (air) atmosphere and in an inert Ar atmosphere. Differences in solid carbon residues were quantified using X-ray photoelectron spectroscopy and carbon isotope measurements. Environmental conditions, HE formulation, and peak pressures influenced the amount of and isotopic composition of the carbon in the soot. Detonations in an Ar atmosphere produced greater amounts of ca...