Dynamic Shock Compression Research Articles

Cylindrical compression of thin wires by irradiation with a Joule-class short-pulse laser

Equation of state measurements at Jovian or stellar conditions are currently conducted by dynamic shock compression driven by multi-kilojoule multi-beam nanosecond-duration lasers. These experiments require precise design of the target and specific tailoring of the spatial and temporal laser profiles to reach the highest pressures. At the same time, the studies are limited by the low repetition rate of the lasers. Here, we show that by the irradiation of a thin wire with single-beam Joule-class short-pulse laser, a converging cylindrical shock is generated compressing the wire material to conditions relevant to the above applications. The shockwave was observed using Phase Contrast Imaging employing a hard X-ray Free Electron Laser with unprecedented temporal and spatial sensitivity. The data collected for Cu wires is in agreement with hydrodynamic simulations of an ablative shock launched by highly impulsive and transient resistive heating of the wire surface. The subsequent cylindrical shockwave travels toward the wire axis and is predicted to reach a compression factor of 9 and pressures above 800 Mbar. Simulations for astrophysical relevant materials underline the potential of this compression technique as a new tool for high energy density studies at high repetition rates.

Investigation into the stability of synthetic goethite after dynamic shock compression

Investigation into the stability of synthetic goethite after dynamic shock compression

Mixture of hydrogen and methane under planetary interior conditions.

We employ first-principles molecular dynamics simulations to provide equation-of-state data, pair distribution functions (PDFs), diffusion coefficients, and band gaps of a mixture of hydrogen and methane under planetary interior conditions as relevant for Uranus, Neptune, and similar icy exoplanets. We test the linear mixing approximation, which is fulfilled within a few percent for the chosen P-T conditions. Evaluation of the PDFs reveals that methane molecules dissociate into carbon clusters and free hydrogen atoms at temperatures greater than 3000 K. At high temperatures, the clusters are found to be short-lived. Furthermore, we calculate the electrical conductivity from which we derive the non-metal-to-metal transition region of the mixture. We also calculate the electrical conductivity along the P-T profile of Uranus [N. Nettelmann et al., Planet. Space Sci., 2013, 77, 143-151] and observe the transition of the mixture from a molecular to an atomic fluid as a function of the radius of the planet. The density and temperature ranges chosen in our study can be achieved using dynamic shock compression experiments and seek to aid such future experiments. Our work also provides a relevant data set for a better understanding of the interior, evolution, luminosity, and magnetic field of the ice giants in our solar system and beyond.

Capturing Polymer Chain Compression and Shock Driven Decomposition of Polytetrafluoroethylene During Dynamic Shock Compression with In Situ X-Ray Diffraction

Capturing Polymer Chain Compression and Shock Driven Decomposition of Polytetrafluoroethylene During Dynamic Shock Compression with In Situ X-Ray Diffraction

Phase transitions of palladium under dynamic shock compression

For palladium (Pd) as a typical high-pressure standard material, studying its structural changes and thermodynamic properties under extreme conditions is widely demanded and challenging. Particularly, the solid-solid phase transition process of Pd under shock loading is understood still scarcely. In this paper, using the classical molecular dynamics simulations with embedded atom method (EAM) based on the interatomic potential, we investigate the phase transition of single crystal Pd from atomic scale under shock loading. A series of structural features is observed in a pressure range of 0–375 GPa, revealing that the structure feature transforms from the initial face-centered cubic (FCC) structure to the stacking faults body-centered cubic (BCC) structure with hexagonal close-packed (HCP) structure, and finally complete melting. Under shock loading of <inline-formula><tex-math id="Z-20220123201122">\begin{document}$ \left\langle {100} \right\rangle $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20211511_Z-20220123201122.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20211511_Z-20220123201122.png"/></alternatives></inline-formula> oriented bulk Pd, we find the transformation to BCC structure can take place almost at 70.0 GPa, which is much lower than the previous static calculation result. In addition, we find that the phase transition depends on the direction initially impacting crystal. Under impacting along the <inline-formula><tex-math id="Z-20220123201132">\begin{document}$ \left\langle {110} \right\rangle $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20211511_Z-20220123201132.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20211511_Z-20220123201132.png"/></alternatives></inline-formula> direction and the <inline-formula><tex-math id="Z-20220123201127">\begin{document}$ \left\langle {111} \right\rangle $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20211511_Z-20220123201127.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20211511_Z-20220123201127.png"/></alternatives></inline-formula> direction, the FCC-BCC phase transition pressures increase to 135.8 GPa and 165.4 GPa, respectively. Also, the introduction of defects will increase the phase transition pressure of FCC-BCC by 20–30 GPa in comparison with perfect crystals, which is verified by the distribution of the potential energy. An interesting phenomenon that FCC-BCC transition pressure of Pd decreases under shock loading is found in this work, which provides a new theoretical insight into the application of high pressure experiments in the future.

The melting curves of tin, uranium, cadmium, thallium and indium metals under pressure

The pressure effects on melting lines of tin, uranium, cadmium, thallium and indium metals have been studied by using the Lindemann melting criterion, the recent well-established Grüneisen parameter, and the third order Birch-Murnaghan equation-of-state up to pressure of 140 GPa. The analytic expression of volume-dependent melting temperature has been derived. Our results are in good agreement with laser-heating diamond-anvil cell measurement but lower than recent shock compression work. This method provides a quick approach to estimate the melting point of tin metal under pressure. Our reported melting temperatures increase the database of high-pressure melting, and could be used to analyze and verify the future high-pressure dynamic shock compression as well as diamond-anvil cell static compression experiments.

New frontiers in extreme conditions science at synchrotrons and free electron lasers

Synchrotrons and free electron lasers are unique facilities to probe the atomic structure and electronic properties of matter at extreme thermodynamical conditions. In this context, ‘matter at extreme pressures and temperatures’ was one of the science drivers for the construction of low emittance 4th generation synchrotron sources such as the Extremely Brilliant Source of the European Synchrotron Radiation Facility and hard x-ray free electron lasers, such as the European x-ray free electron laser. These new user facilities combine static high pressure and dynamic shock compression experiments to outstanding high brilliance and submicron beams. This combination not only increases the data-quality but also enlarges tremendously the accessible pressure, temperature and density space. At the same time, the large spectrum of available complementary x-ray diagnostics for static and shock compression studies opens unprecedented insights into the state of matter at extremes. The article aims at highlighting a new horizon of scientific opportunities based on the synergy between extremely brilliant synchrotrons and hard x-ray free electron lasers.

Phase Transitions of Palladium under Dynamic Shock Compression

Phase Transitions of Palladium under Dynamic Shock Compression

Nanocrystals of face-centred cubic carbon, i-carbon and diamond obtained by direct conversion of graphite at high temperatures and static ultra-high pressures

Until recently graphite, diamond and amorphous carbon were considered to be the only three carbon modifications of a terrestrial origin present in nature. Recently numerous publications indicated the existence of two other uncommon metastable carbon allotropes - face-centred cubic carbon and i‑carbon – on Earth. Nanoparticles of these carbon allotropes were found in carbon spherules of samples taken from soils and rocks in different countries of Europe and North America, crude oil, ice sheets from Greenland, etc. The existence of these metastable carbon allotropes in nature appeared to confirm the Younger Dryas extraterrestrial impact hypothesis proposing such an impact over North America, that caused a global catastrophe and climate change. This hypothesis suggests an extraterrestrial impact origin of these carbon allotropes due to dynamic shock compression, since to date they have only been simultaneously produced in ultra-high pressures dynamic shock experiments. We report the first synthesis of nanocrystals of the both metastable carbon allotropes along with diamond at elevated temperatures and static ultra-high pressures. This provides evidence that nanocrystals of face-centred cubic carbon and i‑carbon present in nature are likely to form in Earth's mantle, so that they have a terrestrial origin. Results of electron diffraction and high-resolution transmission electron microscopy clearly indicate that face-centred cubic carbon and i‑carbon are characterized by unique crystal lattices, which have nothing common with the diamond crystal lattice. These two carbon allotropes are thought to be characterized by unconventional chemical bonds due to unusual combinations of their crystal lattice types and lattice parameters. The nature of chemical bonds in face-centred cubic carbon and i‑carbon is supposed to be different from that of conventional basic chemical bonds (covalent, ionic and metallic bonding as well as the van der Waals forces). These carbon allotropes can therefore possess unique and potentially valuable properties suitable for different applications.

High-speed x-ray phase contrast imaging and digital image correlation analysis of microscale shock response of an additively manufactured energetic material simulant

The performance of energetic materials subjected to dynamic loading significantly depends on their micro- and meso-scale structural morphology. The geometric versatility offered by additive manufacturing opens new pathways to tailor the performance of these materials. Additively manufactured energetic materials (AMEMs) have a wide range of structural characteristics with a hierarchy of length scales and process-inherent heterogeneities, which are hitherto difficult to precisely control. It is important to understand how these features affect AMEMs’ response under dynamic/shock loading. Therefore, temporally and spatially resolved measurements of both macroscopic behavior and micro- and meso-level processes influencing macroscopic behavior are required. In this paper, we analyze the shock compression response of an AMEM simulant loaded under several impact conditions and orientations. X-ray phase contrast imaging (PCI) is used to track features across the observed shock front and determine the linear shock velocity vs particle velocity equation of state, as well as to quantify the interior deformation fields via digital image correlation (DIC) analyses. Photon Doppler velocimetry is simultaneously used to measure the particle velocities of the specimens, which are consistent with those obtained from x-ray PCI. The DIC analyses provide an assessment of the average strain fields inside the material, showing that the average axial strain depends on the loading intensity and reaches as high as 0.23 for impact velocities up to 1.5 km/s. The overall results demonstrate the utility of x-ray PCI for probing “in-material” equation of state and interior strains associated with dynamic shock compression behavior of the AMEM simulant.

A multi-wavelength streaked optical pyrometer for dynamic shock compression measurements above 2500 K.

This article presents a concept and implementation of a calibrated streaked spectral pyrometer (SSP) temperature diagnostic used in dynamically driven shock experiments on a two-stage gas gun. This system relies upon measuring the total system response using a tunable monochromator, a NIST-traceable calibrated power meter, and a SSP. The diagnostic performance is validated against previously measured temperatures of shock driven z-cut quartz at 99 GPa and 93 GPa. The results are found to agree with the literature to within 5% and are discussed in this manuscript. The experimental setup utilizes measurements from multiple SSP systems per sample, providing several independent measurements and substantially increasing confidence in the extrapolated shock driven sample temperature.

Bacterial survival following shock compression in the GigaPascal range

The possibility that life can exist within previously unconsidered habitats is causing us to expand our understanding of potential planetary biospheres. Significant populations of living organisms have been identified at depths extending up to several km below the Earth's surface; whereas laboratory experiments have shown that microbial species can survive following exposure to GigaPascal (GPa) pressures. Understanding the degree to which simple organisms such as microbes survive such extreme pressurization under static compression conditions is being actively investigated. The survival of bacteria under dynamic shock compression is also of interest. Such studies are being partly driven to test the hypothesis of potential transport of biological organisms between planetary systems. Shock compression is also of interest for the potential modification and sterilization of foodstuffs and agricultural products. Here we report the survival of Shewanella oneidensis bacteria exposed to dynamic (shock) compression. The samples examined included: (a) a “wild type” (WT) strain and (b) a “pressure adapted” (PA) population obtained by culturing survivors from static compression experiments to 750MPa. Following exposure to peak shock pressures of 1.5 and 2.5GPa the proportion of survivors was established as the number of colony forming units (CFU) present after recovery to ambient conditions. The data were compared with previous results in which the same bacterial samples were exposed to static pressurization to the same pressures, for 15 minutes each. The results indicate that shock compression leads to survival of a significantly greater proportion of both WT and PA organisms. The significantly shorter duration of the pressure pulse during the shock experiments (2–3 µs) likely contributes to the increased survival of the microbial species. One reason for this can involve the crossover from deformable to rigid solid-like mechanical relaxational behavior that occurs for bacterial cell walls on the order of seconds in the time-dependent strain rate.

Shock compression of [001] single crystal silicon

Silicon is ubiquitous in our advanced technological society, yet our current understanding of change to its mechanical response at extreme pressures and strain-rates is far from complete. This is due to its brittleness, making recovery experiments difficult. High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon (using impedance-matched momentum traps) unveiled remarkable structural changes observed by transmission electron microscopy. As laser energy increases, corresponding to an increase in peak shock pressure, the following plastic responses are are observed: surface cleavage along {111} planes, dislocations and stacking faults; bands of amorphized material initially forming on crystallographic orientations consistent with dislocation slip; and coarse regions of amorphized material. Molecular dynamics simulations approach equivalent length and time scales to laser experiments and reveal the evolution of shock-induced partial dislocations and their crucial role in the preliminary stages of amorphization. Application of coupled hydrostatic and shear stresses produce amorphization below the hydrostatically determined critical melting pressure under dynamic shock compression.

Amorphization and nanocrystallization of silicon under shock compression

High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon unveiled remarkable structural changes above a pressure threshold. Two distinct amorphous regions were identified: (a) a bulk amorphous layer close to the surface and (b) amorphous bands initially aligned with {111} slip planes. Further increase of the laser energy leads to the re-crystallization of amorphous silicon into nanocrystals with high concentration of nano-twins. This amorphization is produced by the combined effect of high magnitude hydrostatic and shear stresses under dynamic shock compression. Shock-induced defects play a very important role in the onset of amorphization. Calculations of the free energy changes with pressure and shear, using the Patel-Cohen methodology, are in agreement with the experimental results. Molecular dynamics simulation corroborates the amorphization, showing that it is initiated by the nucleation and propagation of partial dislocations. The nucleation of amorphization is analyzed qualitatively by classical nucleation theory.

A novel approach to Hugoniot measurements utilizing transparent crystals

A new absolute equation of state measurement technique is described and demonstrated measuring the shock state and the refractive index of MgO up to 226 GPa. This technique utilizes steady shock waves and the high-pressure transparency of MgO under dynamic shock compression and release. Hugoniot measurements performed using this technique are consistent with the previous measurements. A linear dependence of the shocked refractive index and density is observed up to 226 GPa, over a magnitude greater in pressure that previous studies. The transparency of MgO along the principal Hugoniot is higher than any other material reported to date. We observe a significant change in the refractive index of MgO as the Hugoniot elastic limit is exceeded due to the transition from uniaxial to hydrostatic strain. Measurements of the elastic-plastic two-wave structure in MgO indicate a nucleation time for plastic deformation.

Synchrotron X-Ray Diffraction Study of Texture Evolution in 904L Stainless Steel under Dynamic Shock Compression

The influence of strain rate on development of deformation texture under a dynamic shock compression of a 904L stainless steel was quantitatively investigated using synchrotron X-ray diffraction an ...

Universal behaviour of nonmetal–metal Mott transitions in fluid H, N, O, Rb, andCs

The systematics of Mott transitions inlow-Z and alkali fluids H, N, O, Rb, and Cs are discussed. Such transitions have only beenobtained in elemental, monatomic, and disordered systems by using high pressures andtemperatures. By finding elements which undergo this transition, it is possible to testMott’s ideas in systems which are relatively simple. For fluid H, N, and O, 100 GPapressures and K temperatures are required and were achieved by dynamic shock compression. For fluidRb and Cs, 0.01 GPa and K are required and were achieved statically by Hensel et al. Despite the fact thatthese two groups of elements at ambient conditions are so different chemicallyand that pressures required to observe this transition differ by a factor of104 for the two groups, the metallic conductivities are essentially the same for all five and thedensity dependences of their semiconductivities are determined systematically by the radialextents of the electronic charge-density distributions of the various atoms. The latterobservation provides a physical understanding for the Herzfeld criterion of metallization. Itis the tuning of both high pressure and temperature which permits these two apparentlydifferent classes of elements at ambient conditions to become quite similar in nature atextreme conditions.

Synthesis of tungsten carbide by dynamic shock compression of a tungsten–acetylene black powder mixture

In order to synthesize tungsten carbide as a high-temperature structural element by a shock wave technique, a tungsten–acetylene black powder mixture was shock-compressed. The retrieved sample was examined by X-ray diffraction analysis and optical/electron microscopy. A rodlike compact consisting of rounded particles, plates and dendritic particles of WC having a hexagonal structure was formed in the central region of the shocked sample. The component plates of the compact were presumed to grow via solid–vapor–solid or solid–vapor–liquid–solid sequences.

Formation of Cubic Carbon by Dynamic Shock Compression of a Diamond/Amorphous Carbon Powder Mixture

A diamond/amorphous carbon powder mixture was shock-compressed by a rod-in-cylinder method. Characterization by high-resolution electron microscopy (HREM) revealed the formation of several carbon modifications. Beside a large amount of graphite, two cubic phases of carbon, turbostratic carbon and chaoite were detected in small quantities. Different phase transition mechanisms were proposed. High temperatures and high pressures in the powder sample resulted in the transformation of amorphous carbon into graphite. One cubic phase corresponded to a modification of diamond (n-diamond) in a previous report determined by observation of the forbidden {200}, {222} and {420} reflections of cubic diamond. We related the presence of these reflections not to cubic diamond, but to a carbon form with a face-centered-cubic (fcc) lattice formed by local melting of the diamond surface and subsequent rapid quenching, and via a solid-vapor-liquid-solid (SVLS) path of phase transitions in amorphous carbon particles. The second cubic phase originated from the deposition of a gaseous or liquid carbon jet on diamond. The lattice parameter was calculated to a o = 0.432 nm.