Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session R2: Materials in Extremes VIIIFocus
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Sponsoring Units: DCOMP DMP SHOCK Chair: Abigail Hunter, LANL Room: 261 |
Thursday, March 16, 2017 8:00AM - 8:36AM |
R2.00001: Time-dependent freezing of water under shock and ramp loading Invited Speaker: Jonathan Belof Understanding the high-pressure behavior of water remains an area of tremendous interest in physics, chemistry and biology -- elucidation of both the kinetic and thermodynamic properties of water under compression has had impact on models for planetary formation and evolution, and even in the search for life. As laboratory drivers for dynamic compression continue to advance and allow for specific compression paths, we are increasingly confronted with the challenge of interpreting the data in the face of non-equilibrium effects. We present here a model for coupling phase transformation kinetics and hydrodynamics, directed toward the dynamic freezing of water. This theoretical model (based on nucleation and growth concepts) for solidification, constructed from multiple-shock and quasi-isentropic compression experiments as well as molecular dynamics simulations, presents one possible approach. It is found that the phase transition from liquid water to ice VII involves a transient nucleation regime and for which a strong explicit time-dependence enters into the nucleation rate. We conclude by highlighting some anomalies regarding dynamic solidification of water that remain unexplained and propose additional experimental concepts that could shed light on this complex behavior. [Preview Abstract] |
Thursday, March 16, 2017 8:36AM - 8:48AM |
R2.00002: Kinetics of the Phase Transitions in Zr at Ultra High Strain Rates H. B. Radousky, M. R. Armstrong, P. V. Grivickas, J. C. Crowhurst, J. M. Zaug, R. A. Austin, J. L. Belof Zirconium is an excellent material in which to study the kinetics of pressure induced phase transitions. In particular it has a low pressure structural transition near 7 GPa and a higher pressure transition near 35 GPa. We have obtained velocimetry data from micron-thick zirconium films which span this pressure range using our ultrafast laser shock platform to measure the free surface velocity time histories at breakout, and wave arrival times at different film thicknesses. In this study, we have explored using both shock and ramp compression of zirconium at strain rates in the regime up to and above 10$^{\mathrm{9}}$ s-$^{\mathrm{1}}$. The targets consisted of both zirconium films deposited directly on glass slides and on different thickness of aluminum. These experimental results have been coupled with modeling and simulation, which allows analysis of the surface histories using a method that accounts for non-steady wave propagation and time-dependent material behavior. [Preview Abstract] |
Thursday, March 16, 2017 8:48AM - 9:00AM |
R2.00003: Radiance Measurement on Ramp Loaded Tin Jeffrey Nguyen, Minta Akin, Paul Asimow, Neil Holmes An accurate shock temperature is not only an essential component of an equation of state, but also a good measure of a phase transition, its kinetics, and associated thermal transport properties. We present here our recent results on shock-and-ramp-loaded tin samples. Using a graded density impactor, we drive the tin sample through melting with the initial shock and then further ramp-compress it back into the solid phase. We measure particle velocity and thermal emission at the interface between the Sn and a LiF window. The measured particle velocity shows a traditional signature for phase transition, while thermal radiance exhibits a change consistent with the heat of solidification. We will discuss here the mechanical and thermal aspects of this phase transition, its kinetics, and thermal transport issues in this experiment. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. [Preview Abstract] |
Thursday, March 16, 2017 9:00AM - 9:12AM |
R2.00004: THE FIRST OBSERVATION OF THE BCC PHASE IN COMPRESSED ALUMINUM Danae Polsin, T. Boehly, G. Collins, J. Rygg, S. Burns, J. Delettrez, M. Gregor, B. Henderson, D. Fratanduono, R. Smith, R. Kraus, J. Eggert, A. Jenei, D. Swift, F. Coppari, P. Celliers, C. McCoy Ramp compression is used to near isentropically compress Aluminum samples to pressures up to 600 GPa and at temperatures below the melt. Nanosecond in situ X-ray diffraction is performed at University of Rochester's Laboratory for Laser Energetics and the National Ignition Facility to directly measure the crystal struc- ture at pressures where fcc-hcp and hcp-bcc phase transformations of Al exist. Velocimetry provided the pressure in the Al. The fcc-hcp and hpc-bcc transformations are confirmed experimentally at Þ240 GPa and Þ450 GPa, respectively. This is the first experimental evidence of the bcc phase of Al and a confirmation of the fcc-hcp transition previously observed under static compression at 217 GPa. The existence of these solid-solid phase transformations confirms that these transitions occur on the order of tens of nanoseconds time scales. [Preview Abstract] |
Thursday, March 16, 2017 9:12AM - 9:24AM |
R2.00005: Laser induced sub-nanosecond ramp compression of Al and Zr Paulius Grivickas, Michael Armstrong, Jonathan Crowhurst, Joseph Zaug, Harry Radousky, Ryan Austin, Jon Belof Laser driven dynamic compression experiments aim to emulate mechanical impact experiments in producing shock waves for probing well-defined single points in Hugoniot space. Many scientific problems, however, require quasi-isentropic or ramp wave compression which produces different thermodynamic conditions and can span a wider range of the thermodynamic phase space than shock Hugoniot measurements. It is desirable from the laser energy and experimental throughput point of view to keep such ramps as short as possible. But so far laser driven ramps were typically limited to tens of nanoseconds due to a belief that shorter ramps become affected by the kinetics of material transformation which may generate sufficient dissipative energy and deviate significantly from an ideal isentrope. Sub-nanosecond laser driven shock wave experiments in Fe and Al indeed suggest that material transformations happen on 20-100 ps time scales. The role of these effects at the transition point into an isentropic compression, however, is not well understood. In this work we address these questions by compressing Al and Zr thin films with sub-nanosecond scale ramps and analyzing the results using the conventional Lagrangian method and other methods designed to extract strength information. Prepared by LLNL under Contract DE-AC52-07NA27344. [Preview Abstract] |
Thursday, March 16, 2017 9:24AM - 9:36AM |
R2.00006: Ultrafast compression of graphite observed with sub-100 fs time resolution diffraction at LCLS Michael Armstrong, Alexander Goncharov, Jonathan Crowhurst, Joseph Zaug, Harry Radousky, Paulius Grivickas, Sorin Bastea, Nir Goldman, Elissaios Stavrou, Arianna Gleason, Robert Nagler, Hae Ja Lee, Nicholas Holtgrewe, Peter Walter, Vitali Pakaprenka, Inhuk Nam, Eduardo Granados, Clemens Prescher, Batikan Koroglu We will present sub-100 fs time resolution pulsed x-ray diffraction measurements of rapidly compressed highly oriented pyrolytic graphite along its basal plane at the Materials under Extreme Conditions (MEC) sector of the Linac Coherent Light Source (LCLS). These experiments explore the possibility of rapid (100 ps scale) material transformations occurring in materials under very highly anisotropic compression conditions. Under such conditions, non-equilibrium mechanisms may play a role in the transformation process. We will present experimental results and simulations which explore this possibility. Prepared by LLNL under Contract DE-AC52-07NA27344. [Preview Abstract] |
Thursday, March 16, 2017 9:36AM - 9:48AM |
R2.00007: Local fluctuations in the transformation to amorphous diamond from neutron-irradiated graphite and C$_{\mathrm{60}}$ fullerenes under shock-compression Keisuke Niwase, Kazutaka.G. Nakamura, Tadao Iwata Shock compression and rapid quenching (SCARQ) technique is a unique method to obtain metastable carbon materials, transformed from initial carbon phase in a flash. Here, we report local fluctuations in the transformation to amorphous diamond from neutron-irradiated highly oriented pyrolitic graphite (HOPG) and C$_{\mathrm{60}}$ fullerene under SCARQ. For the recovered sample of neutron irradiated graphite, we found an appearance of domain boundary between optically transparent and opaque areas. Raman spectroscopy revealed that the transparent and the opaque areas correspond to transformed and untransformed areas, suggesting some martensitic transformation in the highly disordered structure of neutron irradiated graphite. For C$_{\mathrm{60}}$ fullerene film, on the other hand, we recovered platelets after SCARQ at 52 GPa and observed a small Raman peak of diamond with a background of photo luminescence utilizing 488 nm excitation. The peak shape changed depending on the area or the platelets. Peak fitting revealed that the diamond Raman peak shifts to lower frequency with increasing the peak width and decreasing the peak intensity, indicating local fluctuations in the structure of the recovered sample. [Preview Abstract] |
Thursday, March 16, 2017 9:48AM - 10:00AM |
R2.00008: Shock compression of D2 to 500 GPa along the principal Hugoniot A. Fernandez-Panella, D. Fratanduono, M. Millot, P. Celliers, J. Eggert, M. Gregor, T. R. Boehly, G. W. Collins, M. Desjarlais Impedance-match measurements along the principal Hugoniot of deuterium using an Al standard were carried out about 10 years ago at the OMEGA and the Z facilities. The data at the highest pressures (near 200 GPa) suggest a systematically softer response than current equation of state (EOS) models, although the measurement uncertainties are too large to confirm a disagreement with the models. Below 100 GPa, the Omega data shows a much stiffer response than the Z data, associated to a possible plasma phase transition (PPT). We have investigated these issues with recent experiments at the OMEGA laser facility, and we present new impedance-match data along the deuterium principal Hugoniot as well as double shock data in the 80-500 GPa range obtained with higher measurement accuracy using alpha quartz as the impedance match standard. This new data suggests that the deuterium Hugoniot may indeed be softer than the models predict and it doesn't show sign of a PPT. [Preview Abstract] |
Thursday, March 16, 2017 10:00AM - 10:12AM |
R2.00009: High dynamic range spectroscopic studies of shocked nitromethane Mithun Bhowmick, Erin J. Nissen, Dana D. Dlott In this talk we describe a tabletop apparatus that can reproducibly drive shocks through tiny cells containing liquid arranged in an array for high-throughput shock compression studies. This talk will focus on nitromethane, a liquid reactive to shocks and capable of detonation. In our studies, a laser-driven flyer plate was used to shock nitromethane, and a spectrometer with high dynamic range was employed to measure emission spectra from nanosecond to millisecond time scales. Typically, 50 single-shock experiments were performed per day with precisely controllable shock speeds below, above, or equal to the detonation shock speed. The emission spectra provide temperature histories using the graybody approximation. The ability to conveniently shock nitromethane on a benchtop will be used with isotopically substituted and amine-sensitized nitromethane and in future will be combined with other spectroscopies such as infrared absorption. [Preview Abstract] |
(Author Not Attending)
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R2.00010: Raman spectroscopy of laser shocked polymethyl methacrylate. Vinay Rastogi, Shivanand Chaurasia, C. D. Sijoy, Vinayak Mishra, M. N. Deo, Shashank Chaturvedi, Surinder M. Sharma An understanding of material behavior under shock compression is important for variety of applications such as study of material dynamics, equation of state and chemical reactions. Some interesting and sophisticated experiments are performed during last couples of decades. However, the shock induced changes inside the materials are still not well understood. In this paper the shock response of polymethyl methacrylate (PMMA) under laser driven shock compression has been studied by using pump- probe technique. The C-H stretching mode observed in this study show inhomogeneous broadening, shift to higher frequency and decrease in intensity with pressure. The inhomogeneous broadening of these peaks is considered mainly because of shock pressure gradient and the overlapped Raman peaks of shocked and unshocked region. To estimate the maximum shift under shock compression, it is needed to decompose the Raman spectra and calculate the pressure induced Raman blue shift. The obtained spectra under shock compression are analyzed by fitting double Gaussian peaks. These shock compressed states are also compared with the static compression data, to see if any general trend can be established. [Preview Abstract] |
Thursday, March 16, 2017 10:24AM - 10:36AM |
R2.00011: Ultrafast shock time-of-flight measurements in polymers Joseph Zaug, Michael Armstrong, Jonathan Crowhurst, Harry Radousky, James Lewicki, April Sawvel, Elissaios Stavrou, Paulius Grivickas, Cynthia Alviso, Robert Maxwell We will present measurements of shock speeds in normal and irradiated polymers in nanosecond scale compression experiments using a time-of-flight method. Time-of-flight is commonly applied in longer time scale experiments, but has not typically been used in ultrafast shock compression of transparent materials, where an alternate method employing a shock-induced etalon between the shock front and the drive surface is more straightforward. Yet, when materials undergo shock-induced chemistry, variations in the index of refraction behind the shock front may compromise the conventional interpretation of shock etalon data, reducing confidence the observation of chemistry-induced hydrodynamic changes using this method. In contrast, time-of-flight provides data that is directly comparable to longer time scale gas gun data, and the interpretation of these data is more straightforward. We use both these methods to obtain Hugoniot data from normal and irradiated polymers, where (for some applications) high confidence in the shock behavior of aged material is critical. Prepared by LLNL under Contract DE-AC52-07NA27344. [Preview Abstract] |
Thursday, March 16, 2017 10:36AM - 10:48AM |
R2.00012: Construction of a kinetics model for liquid-to-solid transitions based on atomistic simulations: Extraction of surface free energies and kinetic coefficients Luis Zepeda-Ruiz, Alex A. Chernov, Babak Sadigh, Tomas Oppelstrup, Amit Samanta, Sebastien Hamel, Tomorr Haxhimali, Lorin X. Benedict, Jon L. Belof We discuss work in progress towards a kinetics model for dynamically-driven liquid-solid transitions built from classical MD simulations. Special attention is paid to the growth kinetics of individual solid nuclei at different degrees of undercooling, and a method is presented for extracting solid cluster surface free energies, needed for coarse-grained models of solidification within the framework of an Avrami-like theory. Throughout, the goal of constructing a kinetics model for use in hydrocode simulations is emphasized. [Preview Abstract] |
Thursday, March 16, 2017 10:48AM - 11:00AM |
R2.00013: Kinetics of shock-induced phase transitions in water Philip Myint, Lorin Benedict, Alexander Chernov, Burl Hall, Sebastien Hamel, Babak Sadigh, Jonathan Belof The transition from liquid water to ice VII, a high-pressure solid polymorph of water, is believed to play an important role in the dynamics of the cores of certain outer Solar System planets and their moons. Although there have been some experimental studies over the past decade to study the water-ice VII transition through shock-wave compression, many of the details concerning the phase transition are still poorly understood. We present simulation results that closely match the experimental results, including those from highly overdriven systems where nanosecond freezing has been observed. The results are produced by a large-scale, multiphysics code developed by Lawrence Livermore National Laboratory that is linked to a phase transition kinetics library that we have recently developed. The library employs models based on classical nucleation theory. For example, the phase fraction is evolved in time according to the Kolmogorov-Johnson-Mehl-Avrami equation. Our simulations provide insight into the kinetics of freezing, particularly the importance of accounting for an induction time in the nucleation models. [Preview Abstract] |
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