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219 results on '"Swift, D. C."'

1. Sensitivity of stellar physics to the equation of state

Author

Swift, D. C., Lockard, T., Bethkenhagen, M., Kritcher, A., Hamel, S., and Dearborn, D.

Subjects
Physics - Computational Physics, Astrophysics - Solar and Stellar Astrophysics
Abstract

The formation and evolution of stars depends on various physical aspects of stellar matter, including the equation of state (EOS) and transport properties. Although often dismissed as `ideal gas-like' and therefore simple, states occurring in stellar matter are dense plasmas, and the EOS has not been established precisely. EOS constructed using multi-physics approaches found necessary for laboratory studies of warm dense matter give significant variations in stellar regimes, and vary from the EOS commonly used in simulations of the formation and evolution of stars. We have investigated the sensitivity of such simulations to variations in the EOS, for sun-like and low-mass stars, and found a strong sensitivity of the lifetime of the Sun and of the lower luminosity limit for red dwarfs. We also found a significant sensitivity in the lower mass limit for red dwarfs. Simulations of this type are also used for other purposes in astrophysics, including the interpretation of absolute magnitude as mass, the conversion of inferred mass distribution to the initial mass function using predicted lifetimes, simulations of star formation from nebulae, simulations of galactic evolution, and the baryon census used to bound the exotic contribution to dark matter. Although many of the sensitivities of stellar physics to the EOS are large, some of the inferred astrophysical quantities are also constrained by independent measurements, although the constraints may be indirect and non-trivial. However, it may be possible to use such measurements to constrain the EOS more than presently possible by established plasma theory.

Published
2020

2. Time resolved x-ray diffraction using the flexible imaging diffraction diagnostic for laser experiments (FIDDLE) at the National Ignition Facility (NIF): Preliminary assessment of diffraction precision.

Author

Vennari, C. E., Palmer, N. E., Nyholm, P. R., Bhandakar, N. S., Nagel, S. R., Petre, R. B., Stan, C. V., Eggert, J. H., Bradley, D. K., Ping, Y., Thomas, A., Swift, D. C., Carpenter, A. C., MacKinnon, A. J., and Benedetti, L. R.

Subjects
FACE centered cubic structure, TIME pressure, DIAGNOSTIC imaging, X-ray diffraction, VIOLIN
Abstract

The Flexible Imaging Diffraction Diagnostic for Laser Experiments (FIDDLE) is a new diagnostic at the National Ignition Facility (NIF) designed to observe in situ solid–solid phase changes at high pressures using time resolved x-ray diffraction. FIDDLE currently incorporates five Icarus ultrafast x-ray imager sensors that take 2 ns snapshots and can be tuned to collect X-rays for tens of ns. The platform utilizes the laser power at NIF for both the laser drive and the generation of 10 keV X-rays for ∼10 ns using a Ge backlighter foil. We aim to use FIDDLE to observe diffraction at different times during compression to probe the kinetics of phase changes. Pb undergoes two solid–solid phase transitions during ramp compression: from face centered cubic (FCC) to hexagonal close packed (HCP) and HCP to body centered cubic (BCC). Results will be reported on some of the first shots using the FIDDLE diagnostic at NIF on ramp compressed Pb to a peak pressure of ∼110 GPa and a single undriven CeO2 calibration shot. A discussion of the uncertainties in the observed diffraction is included. [ABSTRACT FROM AUTHOR]

Published
2024
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3. Metastability of diamond ramp-compressed to 2 terapascals

Author

Lazicki, A., McGonegle, D., Rygg, J. R., Braun, D. G., Swift, D. C., Gorman, M. G., and Smith, R. F.

Subjects
Compressibility -- Measurement, Diamond crystals -- Mechanical properties -- Structure, Carbon allotropes -- Mechanical properties -- Identification and classification, Diamonds -- Mechanical properties -- Structure, Metastability -- Analysis, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Carbon is the fourth-most prevalent element in the Universe and essential for all known life. In the elemental form it is found in multiple allotropes, including graphite, diamond and fullerenes, and it has long been predicted that even more structures can exist at pressures greater than those at Earth's core.sup.1-3. Several phases have been predicted to exist in the multi-terapascal regime, which is important for accurate modelling of the interiors of carbon-rich exoplanets.sup.4,5. By compressing solid carbon to 2 terapascals (20 million atmospheres; more than five times the pressure at Earth's core) using ramp-shaped laser pulses and simultaneously measuring nanosecond-duration time-resolved X-ray diffraction, we found that solid carbon retains the diamond structure far beyond its regime of predicted stability. The results confirm predictions that the strength of the tetrahedral molecular orbital bonds in diamond persists under enormous pressure, resulting in large energy barriers that hinder conversion to more-stable high-pressure allotropes.sup.1,2, just as graphite formation from metastable diamond is kinetically hindered at atmospheric pressure. This work nearly doubles the highest pressure at which X-ray diffraction has been recorded on any material. X-ray diffraction measurements of solid carbon compressed to pressures of about two terapascals (approximately twenty million atmospheres) find that carbon retains a diamond structure even under these extreme conditions., Author(s): A. Lazicki [sup.1] , D. McGonegle [sup.2] , J. R. Rygg [sup.3] [sup.4] [sup.5] , D. G. Braun [sup.1] , D. C. Swift [sup.1] , M. G. Gorman [sup.1] [...]

Published
2021
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6. Ab fere initio equations of mechanical state

Author

Swift, D. C.

Subjects
530.1
Abstract

This thesis describes the development and application of models to predict the equation of mechanical state of materials from first principles, concentrating on the regime of strong shock waves. Most effort was devoted to crystalline solids, though extensions to the fluid phase and higher temperatures are proposed. Equations of state and phase diagrams were predicted for aluminium, silicon and beryllium. The method used is based on quantum mechanical treatments of the electrons in the solid and of the phonon modes. The importance of anharmonic effects (phonon-phonon interactions) was investigated, but was not included rigorously because it did not appear to contribute significantly. With fully ab initio methods, the equation of state and phase diagram could be predicted to a few percent in mass density, the discrepancy being caused mainly by the use of the local density approximation in predicting electron states. The accuracy of the equation of state could be improved considerably by adjusting the internal energy to reproduce the observed mass density at STP. The resulting ab fere initio equation of state could essentially reproduce the observed states on the shock Hugoniot to within the scatter in the experimental data. Because these equations of state are built on firm quantum mechanical and thermodynamic principles, they should predict accurate properties away from the principal Hugoniot, unlike traditional empirical equations of state. Accurate temperatures are important in the development of models of material strength (elasticity and plasticity) based on microstructural phenomena. As an illustration of the versatility of the equations of state, hydrocode simulations were made of the splitting of a shock wave in silicon, caused by the phase change. The splitting appears to be in reasonable agreement with laser-driven shock experiments.

Published
2000

7. Laser-driven Rayleigh-Taylor instability experiments on solid copper along two different adiabatic paths.

Author

Lockard, T. E., Kim, Y.-J., Powell, P. D., Park, H.-S., Rudd, R. E., McNaney, J. M., and Swift, D. C.

Subjects
RAYLEIGH-Taylor instability, COPPER, LASER pulses, HIGH temperatures, DIAMOND anvil cell, RADIOGRAPHY, MODULATIONAL instability
Abstract

We present the design of laser-driven materials experiments conducted at the OMEGA-EP laser facility. These experiments measure ripple growth via the Rayleigh-Taylor (RT) instability in solid copper to understand its dynamic strength under high pressure and high temperature conditions. Historically, these ramp-compression experiments have been carried out by releasing a reservoir of layered materials across a gap and onto a second stack of materials that encase the target sample. In the experimental designs considered in this manuscript the target stack containing the copper sample is directly irradiated by the laser; ramp-compression is achieved through laser pulse shaping. The sample is designed to follow two different loading paths to megabar pressures: first, using a smooth ramp, yielding a low-temperature adiabatic path; second by shocking to a given pressure and then accelerating the sample along a high-temperature adiabat path. Strength is inferred from experimentally obtained measurements using face-on radiography of ripple growth that is compared to simulated growth using different strength models. [ABSTRACT FROM AUTHOR]

Published
2023
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8. Ramp compression of tantalum to multiterapascal pressures: Constraints of the thermal equation of state to 2.3 TPa and 5000 K

Author

Gorman, M. G., primary, Wu, C. J., additional, Smith, R. F., additional, Benedict, L. X., additional, Prisbrey, C. J., additional, Schill, W., additional, Bonev, S. A., additional, Long, Z. C., additional, Söderlind, P., additional, Braun, D., additional, Swift, D. C., additional, Briggs, R., additional, Volz, T. J., additional, O'Bannon, E. F., additional, Celliers, P. M., additional, Fratanduono, D. E., additional, Eggert, J. H., additional, Ali, S. J., additional, and McNaney, J. M., additional

Published
2023
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9. Shocked materials at the intersection of experiment and simulation

Author

Lorenzana, H. E., Belak, J. F., Bradley, K. S., Bringa, E. M., Budil, K. S., Cazamias, J. U., El-Dasher, B., Hawreliak, J. A., Hessler, J., Kadau, K., Kalantar, D. H., McNaney, J. M., Milathianaki, D., Rosolankova, K., Swift, D. C., Taravillo, M., Van Buuren, T. W., Wark, J. S., de la Rubia, T. Diaz, Barth, Timothy J., editor, Griebel, Michael, editor, Keyes, David E., editor, Nieminen, Risto M., editor, Roose, Dirk, editor, Schlick, Tamar, editor, Yip, Sidney, editor, and de la Rubia, Tomás Diaz, editor

Published
2009
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10. Development of uncertainty-aware equation-of-state models: Application to copper.

Author

Ali, S. J., Swift, D. C., Wu, C. J., and Kraus, R. G.

Subjects
*EQUATIONS of state, *APPLIED sciences, *SCIENTIFIC community, *NATURAL history, *UNCERTAINTY
Abstract

Sophisticated hydrodynamic codes are commonly used to understand and predict events relevant to natural and applied sciences. The degree to which these simulations reflect reality, however, is dependent on how well we understand the materials and underlying physics involved. These research communities need material models that communicate the uncertainty in the physical properties, which at their basest form comes from the uncertainty in the underlying experimental measurements. We have constructed a new framework for using both experimental measurements and the associated experimental uncertainties to build equation-of-state models that reflect not only current best measurements but also the accuracy of those measurements. This method had been used to construct an ensemble of equation-of-state models for copper that communicates the experimental uncertainties in the data through the equation-of-state model, which is available for application in any simulation metric of interest. [ABSTRACT FROM AUTHOR]

Published
2020
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14. Using neutrons and x rays to measure plasma conditions in a solid sphere of deuterated polyethylene compressed to densities of 35 g/cc at temperatures of 2 keV and pressures of 40 Gbar

Author

Nilsen, J., primary, Bachmann, B., additional, Zimmerman, G. B., additional, Hatarik, R., additional, Döppner, T., additional, Swift, D. C., additional, Hawreliak, J., additional, Collins, G. W., additional, Falcone, R. W., additional, Glenzer, S. H., additional, Kraus, D., additional, Landen, O. L., additional, Castor, J. I., additional, Whitley, H. D., additional, and Kritcher, A. L., additional

Published
2021
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15. Shocked materials at the intersection of experiment and simulation

Author

Lorenzana, H. E., Belak, J. F., Bradley, K. S., Bringa, E. M., Budil, K. S., Cazamias, J. U., El-Dasher, B., Hawreliak, J. A., Hessler, J., Kadau, K., Kalantar, D. H., McNaney, J. M., Milathianaki, D., Rosolankova, K., Swift, D. C., Taravillo, M., Van Buuren, T. W., Wark, J. S., and de la Rubia, T. Diaz

Published
2008
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16. Using neutrons and x rays to measure plasma conditions in a solid sphere of deuterated polyethylene compressed to densities of 35 g/cc at temperatures of 2 keV and pressures of 40 Gbar

Author

Nilsen, J., Bachmann, B., Zimmerman, G. B., Hatarik, R., Döppner, T., Swift, D. C., Hawreliak, J., Collins, G. W., Falcone, R. W., Glenzer, S. H., (0000-0002-6350-4180) Kraus, D., Landen, O. L., Castor, J. I., Whitley, H. D., Kritcher, A. L., Nilsen, J., Bachmann, B., Zimmerman, G. B., Hatarik, R., Döppner, T., Swift, D. C., Hawreliak, J., Collins, G. W., Falcone, R. W., Glenzer, S. H., (0000-0002-6350-4180) Kraus, D., Landen, O. L., Castor, J. I., Whitley, H. D., and Kritcher, A. L.

Abstract

This paper describes an experiment that shock compresses the center of a solid deuterated polyethylene sphere, CD2, to densities of 35 g/cc and temperatures of 2 keV with corresponding pressure of 40 Gbar. The design employs a strong spherically converging shock launched through a solid ball of material using a Hohlraum radiation drive. As the shock coalesces at the center it produces a hot spot that we characterize by measuring the x-ray self-emission and 2.45MeV neutrons emitted. Two-dimensional images and time-resolved measurements of the x rays emitted determine the size and time duration of the hot spot, leading to an estimated 2 keV electron temperature. The neutron time of flight spectrometer measures an average ion temperature of 1.06 +/- 0.15 keV and neutron yield of 7.0 (+/-0.5) x 10^9 DD neutrons. Our new distribution function tool enables us to create a forward model of the experimental data based on 1D radiation-hydrodynamic simulations, leading to a better understanding of the plasma conditions that produce the measured neutrons and x rays. Our simulations indicate that the x rays are produced in a short-lived hot-dense core over tens of picoseconds, whereas the neutron emission continues for about 200 ps, as the hot core starts to expand, thereby leading to a lower mean temperature of the plasma during neutron production. This finding is in agreement with the experimental data, and we therefore conclude that the forward-modeling is a useful tool forinferring the conditions of the hot spot in a laser-driven implosion during burn.

Published
2021

17. Simultaneous compression and opacity data from time-series radiography with a Lagrangian marker

Author

Swift, D. C., Kritcher, A. L., Hawreliak, J. A., Gaffney, J., Lazicki, A., Macphee, A., Bachmann, B., Döppner, T., Nilsen, J., Whitley, H. D., Collins, G. W., Glenzer, S., Rothman, S. D., (0000-0002-6350-4180) Kraus, D., Falcone, R. W., Swift, D. C., Kritcher, A. L., Hawreliak, J. A., Gaffney, J., Lazicki, A., Macphee, A., Bachmann, B., Döppner, T., Nilsen, J., Whitley, H. D., Collins, G. W., Glenzer, S., Rothman, S. D., (0000-0002-6350-4180) Kraus, D., and Falcone, R. W.

Abstract

Time-resolved radiography can be used to obtain absolute shock Hugoniot states by simultaneously measuring at least two mechanical parameters of the shock, and this technique is particularly suitable for one-dimensional converging shocks where a single experiment probes a range of pressures as the converging shock strengthens. However, at sufficiently high pressures, the shocked material becomes hot enough that the x-ray opacity falls significantly. If the system includes a Lagrangian marker such that the mass within the marker is known, this additional information can be used to constrain the opacity as well as the Hugoniot state. In the limit that the opacity changes only on shock heating, and not significantly on subsequent isentropic compression, the opacity of the shocked material can be determined uniquely. More generally, it is necessary to assume the form of the variation of opacity with isentropic compression or to introduce multiple marker layers. Alternatively, assuming either the equation of state or the opacity, the presence of a marker layer in such experiments enables the non-assumed property to be deduced more accurately than from the radiographic density reconstruction alone. An example analysis is shown for measurements of a converging shock wave in polystyrene at the National Ignition Facility.

Published
2021

18. High resolution >40 keV x-ray radiography using an edge-on micro-flag backlighter at NIF-ARC

Author

Hill, M. P., primary, Williams, G. J., additional, Zylstra, A. B., additional, Stan, C. V., additional, Lockard, T. E., additional, Gumbrell, E. T., additional, Rudd, R. E., additional, Powell, P. D., additional, Swift, D. C., additional, McNaney, J. M., additional, Le Galloudec, K. K., additional, Remington, B. A., additional, and Park, H. -S., additional

Published
2021
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19. An iterative forward analysis technique to determine the equation of state of dynamically compressed materials.

Author

Ali, S. J., Kraus, R. G., Fratanduono, D. E., Swift, D. C., and Eggert, J. H.

Subjects
EQUATIONS of state, COMPRESSION (Audiology), HYDRODYNAMICS, COMPUTER simulation, LAGRANGIAN functions, ITERATIVE methods (Mathematics)
Abstract

We developed an iterative forward analysis (IFA) technique with the ability to use hydrocode simulations as a fitting function for analysis of dynamic compression experiments. The IFA method optimizes over parameterized quantities in the hydrocode simulations, breaking the degeneracy of contributions to the measured material response. Velocity profiles from synthetic data generated using a hydrocode simulation are analyzed as a first-order validation of the technique. We also analyze multiple magnetically driven ramp compression experiments on copper and compare with more conventional techniques. Excellent agreement is obtained in both cases. [ABSTRACT FROM AUTHOR]

Published
2017
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20. X-ray diffraction at the National Ignition Facility

Author

Rygg, J. R., primary, Smith, R. F., additional, Lazicki, A. E., additional, Braun, D. G., additional, Fratanduono, D. E., additional, Kraus, R. G., additional, McNaney, J. M., additional, Swift, D. C., additional, Wehrenberg, C. E., additional, Coppari, F., additional, Ahmed, M. F., additional, Barrios, M. A., additional, Blobaum, K. J. M., additional, Collins, G. W., additional, Cook, A. L., additional, Di Nicola, P., additional, Dzenitis, E. G., additional, Gonzales, S., additional, Heidl, B. F., additional, Hohenberger, M., additional, House, A., additional, Izumi, N., additional, Kalantar, D. H., additional, Khan, S. F., additional, Kohut, T. R., additional, Kumar, C., additional, Masters, N. D., additional, Polsin, D. N., additional, Regan, S. P., additional, Smith, C. A., additional, Vignes, R. M., additional, Wall, M. A., additional, Ward, J., additional, Wark, J. S., additional, Zobrist, T. L., additional, Arsenlis, A., additional, and Eggert, J. H., additional

Published
2020
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21. Nonisentropic Release of a Shocked Solid

Author

Heighway, Patrick, Sliwa, M., McGonegle, David, Wehrenberg, C. E., Bolme, C., Eggert, J.H., Higginbotham, Andrew, Lazicki, A. E., Lee, Hae Ja, Nagler, Bob, Park, Hye-Sook, Rudd, R. E., Smith, R. F., Suggit, Mathew, Swift, D. C., Tavella, F., Remington, Bruce A., and Wark, J S

Abstract

We present molecular dynamics (MD) simulations of shock and release in micron-scale tantalum crystals that exhibit post-breakout temperatures far exceeding those expected under the standard assumption of isentropic release. We show via an energy-budget analysis that this is due to plastic-work heating from material strength that largely counters thermoelastic cooling. The simulations are corroborated by experiments where the release temperatures of laser-shocked tantalum foils are deduced from their thermal strains via in situ x-ray diffraction, and are found to be close to those behind the shock.

Published
2019

22. Probing the Solid Phase of Noble Metal Copper at Terapascal Conditions

Author

Fratanduono, D. E., primary, Smith, R. F., additional, Ali, S. J., additional, Braun, D. G., additional, Fernandez-Pañella, A., additional, Zhang, S., additional, Kraus, R. G., additional, Coppari, F., additional, McNaney, J. M., additional, Marshall, M. C., additional, Kirch, L. E., additional, Swift, D. C., additional, Millot, M., additional, Wicks, J. K., additional, and Eggert, J. H., additional

Published
2020
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23. Extreme Hardening of Pb at High Pressure and Strain Rate

Author

Krygier, A., primary, Powell, P. D., additional, McNaney, J. M., additional, Huntington, C. M., additional, Prisbrey, S. T., additional, Remington, B. A., additional, Rudd, R. E., additional, Swift, D. C., additional, Wehrenberg, C. E., additional, Arsenlis, A., additional, Park, H.-S., additional, Graham, P., additional, Gumbrell, E., additional, Hill, M. P., additional, Comley, A. J., additional, and Rothman, S. D., additional

Published
2019
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25. Absolute Equation-of-State Measurement for Polystyrene from 25 - 60 Mbar Using a Spherically Converging Shock Wave

Author

Döppner, T., Swift, D. C., Kritcher, A. L., Bachmann, B., Collins, G. W., Chapman, D. A., Hawreliak, J., Kraus, D., Nilsen, J., Rothman, S., Benedict, L. X., Dewald, E., Fratanduono, D. E., Gaffney, J. A., Glenzer, S. H., Hamel, S., Landen, O. L., Lee, H. J., Lepape, S., Ma, T., Macdonald, M. J., Macphee, A., Milathianaki, D., Millot, M., Neumayer, P., Sterne, P. A., Tommasini, R., and Falcone, R. W.

Abstract

We have developed an experimental platform for the National Ignition Facility (NIF) that uses spherically converging shock waves for absolute equation of state (EOS) measurements along the principal Hugoniot. In this Letter we present radiographic compression measurements for polystyrene that were taken at shock pressures reaching 60 Mbar (6 TPa). This significantly exceeds previously published results obtained on the Nova laser [Cauble et al., Phys. Rev. Lett. 80, 1248 (1998)] at strongly improved precision, allowing to discriminate between different EOS models. We find excellent agreement with Kohn-Sham Density Functional Theory based molecular dynamics simulations.

Published
2018

26. Absolute Hugoniot measurements from a spherically-convergent shock using x-ray radiography

Author

Swift, D. C., Kritcher, A., Hawreliak, J., Lazicki, A., Macphee, A., Bachmann, B., Döppner, T., Nilsen, J., Collins, G. W., Glenzer, S., Rothman, S. D., Kraus, D., and Falcone, R. W.

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Galaxy Astrophysics
Abstract

The canonical high pressure equation of state measurement is to induce a shock wave in the sample material and measure two mechanical properties of the shocked material or shock wave. For accurate measurements, the experiment is normally designed to generate a planar shock which is as steady as possible in space and time, and a single state is measured. A converging shock strengthens as it propagates, so a range of shock pressures is induced in a single experiment. However, equation of state measurements must then account for spatial and temporal gradients. We have used x-ray radiography of spherically-converging shocks to determine states along the shock Hugoniot. The radius-time history of the shock, and thus its speed, was measured by radiographing the position of the shock front as a function of time using an x-ray streak camera. The density profile of the shock was then inferred from the x-ray transmission at each instant of time. Simultaneous measurement of the density at the shock front and the shock speed determines an absolute mechanical Hugoniot state. The density profile was reconstructed using the known, unshocked density which strongly constrains the density jump at the shock front. The radiographic configuration and streak camera behavior were treated in detail to reduce systematic errors. Measurements were performed on the Omega and National Ignition Facility lasers, using a hohlraum to induce a spatially uniform drive over the outside of a solid, spherical sample, and a laser-heated thermal plasma as an x-ray source for radiography. Absolute shock Hugoniot measurements were demonstrated for carboncontaining samples of different composition and initial density, up to temperatures at which K-shell ionization reduced the opacity behind the shock. Here we present the experimental method, using measurements of polystyrene as an example.

Published
2018

27. X-ray diffraction of ramp-compressed aluminum to 475 GPa

Author

Polsin, D. N., primary, Fratanduono, D. E., additional, Rygg, J. R., additional, Lazicki, A., additional, Smith, R. F., additional, Eggert, J. H., additional, Gregor, M. C., additional, Henderson, B. J., additional, Gong, X., additional, Delettrez, J. A., additional, Kraus, R. G., additional, Celliers, P. M., additional, Coppari, F., additional, Swift, D. C., additional, McCoy, C. A., additional, Seagle, C. T., additional, Davis, J.-P., additional, Burns, S. J., additional, Collins, G. W., additional, and Boehly, T. R., additional

Published
2018
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28. Absolute Equation-of-State Measurement for Polystyrene from 25 to 60 Mbar Using a Spherically Converging Shock Wave

Author

Döppner, T., primary, Swift, D. C., additional, Kritcher, A. L., additional, Bachmann, B., additional, Collins, G. W., additional, Chapman, D. A., additional, Hawreliak, J., additional, Kraus, D., additional, Nilsen, J., additional, Rothman, S., additional, Benedict, L. X., additional, Dewald, E., additional, Fratanduono, D. E., additional, Gaffney, J. A., additional, Glenzer, S. H., additional, Hamel, S., additional, Landen, O. L., additional, Lee, H. J., additional, LePape, S., additional, Ma, T., additional, MacDonald, M. J., additional, MacPhee, A. G., additional, Milathianaki, D., additional, Millot, M., additional, Neumayer, P., additional, Sterne, P. A., additional, Tommasini, R., additional, and Falcone, R. W., additional

Published
2018
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29. High strain-rate plastic flow in Al and Fe.

Author

Smith, R. F., Eggert, J. H., Rudd, R. E., Swift, D. C., Bolme, C. A., and Collins, G. W.

Subjects
MATERIAL plasticity, ALUMINUM, IRON, METAL foils, LASERS, STATISTICAL correlation, PHONONS, ALLOYS
Abstract

Thin Fe and Al foils were ramp-compressed over several to tens of ns timescales to study the time-dependence associated with the onset of plastic flow. Peak stress states of 15-200 GPa were achieved through laser ramp-compression where the strain rate was varied, shot-to-shot, between 106 to 108 s-1. Our data combined with data from other dynamic compression platforms reveals a strong correlation between the peak elastic precursor stress, σE, and the strain rate at the onset of plastic flow, &eh;p. In fcc Al, phonon drag dislocation flow dominates above &eh;p~103s-1 and σE ∼ 0.03 GPa where σE scales as &eh;p0.43. By contrast, the Al alloy 6061-T6 exhibits a relatively weak dependency of σE with &eh;p up to strain rates of ∼107 s-1. Our Fe data, reveals a sharp increase in σE at &eh;p>5×106s-1. This is consistent with a transition in plastic flow to a phonon drag regime. [ABSTRACT FROM AUTHOR]

Published
2011
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30. Use of IR pyrometry to measure free-surface temperatures of partially melted tin as a function of shock pressure.

Author

Seifter, A., Furlanetto, M. R., Grover, M., Holtkamp, D. B., Macrum, G. S., Obst, A. W., Payton, J. R., Stone, J. B., Stevens, G. D., Swift, D. C., Tabaka, L. J., Turley, W. D., and Veeser, L. R.

Subjects
PYROMETRY, FREE surfaces (Crystallography), MECHANICAL shock, PRESSURE, SHOCK waves
Abstract

Equilibrium equation of state theory predicts that the free-surface release temperature of shock-loaded tin will show a plateau at 505 K in the stress range from 19.5 to 33.0 GPa, corresponding to the solid-liquid, mixed-phase region of tin. In this paper we report free-surface temperature measurements on shock-loaded tin from 15 to 31 GPa using multiwavelength optical pyrometry. The shock waves were generated by direct contact of detonating high explosive with a tin sample, and the stress in the sample was determined by free-surface velocity measurements using photon Doppler velocimetry. We measured the emitted thermal radiance in the near IR region at four wavelengths from 1.5 to 5.0 μm. Above 25 GPa the measured free-surface temperatures were higher than the predicted 505 K, and they increased with increasing stress. This deviation may be explained by hot spots and/or variations in surface emissivity, and it may indicate a weakness in the use of a simple analysis of multiwavelength pyrometry data for conditions, such as above the melt threshold, where hot spots or emissivity variations may be significant. We are continuing to study the discrepancy to determine its cause. [ABSTRACT FROM AUTHOR]

Published
2009
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32. Erratum: Measurement of Body-Centered-Cubic Aluminum at 475 GPa [Phys. Rev. Lett. 119 , 175702 (2017)]

Author

Polsin, D. N., primary, Fratanduono, D. E., additional, Rygg, J. R., additional, Lazicki, A., additional, Smith, R. F., additional, Eggert, J. H., additional, Gregor, M. C., additional, Henderson, B. H., additional, Delettrez, J. A., additional, Kraus, R. G., additional, Celliers, P. M., additional, Coppari, F., additional, Swift, D. C., additional, McCoy, C. A., additional, Seagle, C. T., additional, Davis, J.-P., additional, Burns, S. J., additional, Collins, G. W., additional, and Boehly, T. R., additional

Published
2018
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33. Modeling laser-driven high-rate plasticity in BCC lead

Author

Rudd, Robert E., primary, Yang, L. H., additional, Powell, P. D., additional, Graham, P., additional, Arsenlis, A., additional, Cavallo, R. M., additional, Krygier, A. G., additional, McNaney, J. M., additional, Prisbrey, S. T., additional, Remington, B. A., additional, Swift, D. C., additional, Wehrenberg, C. E., additional, and Park, H.-S., additional

Published
2018
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34. Measurement of Body-Centered-Cubic Aluminum at 475 GPa

Author

Polsin, D. N., primary, Fratanduono, D. E., additional, Rygg, J. R., additional, Lazicki, A., additional, Smith, R. F., additional, Eggert, J. H., additional, Gregor, M. C., additional, Henderson, B. H., additional, Delettrez, J. A., additional, Kraus, R. G., additional, Celliers, P. M., additional, Coppari, F., additional, Swift, D. C., additional, McCoy, C. A., additional, Seagle, C. T., additional, Davis, J.-P., additional, Burns, S. J., additional, Collins, G. W., additional, and Boehly, T. R., additional

Published
2017
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35. Shock equation of state of LiH6 to 1.1 TPa

Author

Lazicki, A., primary, London, R. A., additional, Coppari, F., additional, Erskine, D., additional, Whitley, H. D., additional, Caspersen, K. J., additional, Fratanduono, D. E., additional, Morales, M. A., additional, Celliers, P. M., additional, Eggert, J. H., additional, Millot, M., additional, Swift, D. C., additional, Collins, G. W., additional, Kucheyev, S. O., additional, Castor, J. I., additional, and Nilsen, J., additional

Published
2017
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38. X-ray scattering measurements on imploding CH spheres at the National Ignition Facility

Author

Kraus, D., primary, Chapman, D. A., additional, Kritcher, A. L., additional, Baggott, R. A., additional, Bachmann, B., additional, Collins, G. W., additional, Glenzer, S. H., additional, Hawreliak, J. A., additional, Kalantar, D. H., additional, Landen, O. L., additional, Ma, T., additional, Le Pape, S., additional, Nilsen, J., additional, Swift, D. C., additional, Neumayer, P., additional, Falcone, R. W., additional, Gericke, D. O., additional, and Döppner, T., additional

Published
2016
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40. Direct Observation of Melting in Shock-Compressed Bismuth With Femtosecond X-ray Diffraction

Author

Gorman, M. G., primary, Briggs, R., additional, McBride, E. E., additional, Higginbotham, A., additional, Arnold, B., additional, Eggert, J. H., additional, Fratanduono, D. E., additional, Galtier, E., additional, Lazicki, A. E., additional, Lee, H. J., additional, Liermann, H. P., additional, Nagler, B., additional, Rothkirch, A., additional, Smith, R. F., additional, Swift, D. C., additional, Collins, G. W., additional, Wark, J. S., additional, and McMahon, M. I., additional

Published
2015
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41. X-Ray Diffraction of Solid Tin to 1.2 TPa

Author

Lazicki, A., primary, Rygg, J. R., additional, Coppari, F., additional, Smith, R., additional, Fratanduono, D., additional, Kraus, R. G., additional, Collins, G. W., additional, Briggs, R., additional, Braun, D. G., additional, Swift, D. C., additional, and Eggert, J. H., additional

Published
2015
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42. Temperature Dependence of Dynamic Deformation in FCC Metals, Aluminum and Invar.

Author

Chen, Laura, Swift, D. C., Austin, R. A., Florando, J. N., Hawreliak, J., Lazicki, A., Saculla, M. D., Eakins, D., Bernier, J. V., and Kumar, M.

Subjects
*THERMISTORS, *HEAVY metals, *ALUMINUM silicates, *CHEMICAL elements, *SHOCK waves
Abstract

Laser-driven shock experiments were performed on fcc metals, aluminum and invar, at a range of initial temperatures from approximately 120-800 K to explore the e ect of initial temperature on dynamic strength properties at strain rates reaching up to 107 s-1. In aluminum, velocimetry data demonstrated an increase of peak stress of the elastic wave, σE, with initial temperature. Alternatively, for invar, σE exhibits little-to-no decrease over the same initial temperature range. Aluminum's unusual deformation behavior is found to primarily be due to anharmonic vibrational e ects. Di erences in the magnetic structure of aluminum and invar can account for discrepancies in high rate deformation behavior. [ABSTRACT FROM AUTHOR]

Published
2017
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43. X-ray continuum emission spectroscopy from hot dense matter at Gbar pressures

Author

Kraus, D., primary, Döppner, T., additional, Kritcher, A. L., additional, Bachmann, B., additional, Chapman, D. A., additional, Collins, G. W., additional, Glenzer, S. H., additional, Hawreliak, J. A., additional, Landen, O. L., additional, Ma, T., additional, Le Pape, S., additional, Neumayer, P., additional, Swift, D. C., additional, and Falcone, R. W., additional

Published
2014
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44. X-ray Thomson scattering as a temperature probe for Gbar shock experiments

Author

Döppner, T, primary, Kritcher, A L, additional, Kraus, D, additional, Glenzer, S H, additional, Bachmann, B L, additional, Chapman, D, additional, Collins, G W, additional, Falcone, R W, additional, Hawreliak, J, additional, Landen, O L, additional, Lee, H J, additional, Pape, S Le, additional, Ma, T, additional, Neumayer, P, additional, Redmer, R, additional, and Swift, D C, additional

Published
2014
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48. Production of Neutrons up to 18 MeV in High-Intensity, Short-Pulse Laser Matter Interactions

Author

LAWRENCE LIVERMORE NATIONAL LAB CA, Higginson, D P, McNaney, J M, Swift, D C, Petrov, G M, Davis, J, Frenje, J A, Jarrott, L C, Kodama, R, Lancaster, K L, Mackinnon, A J, LAWRENCE LIVERMORE NATIONAL LAB CA, Higginson, D P, McNaney, J M, Swift, D C, Petrov, G M, Davis, J, Frenje, J A, Jarrott, L C, Kodama, R, Lancaster, K L, and Mackinnon, A J

Abstract

The generation of high-energy neutrons using laser-accelerated ions is demonstrated experimentally using the Titan laser with 360 J of laser energy in a 9 ps pulse. In this technique, a short-pulse, high-energy laser accelerates deuterons from a CD2 foil. These are incident on a LiF foil and subsequently create high energy neutrons through the 7Li(d,xn) nuclear reaction (Q=15 MeV). Radiochromic film and a Thomson parabola ion-spectrometer were used to diagnose the laser accelerated deuterons and protons. Conversion efficiency into protons was 0.5%, an order of magnitude greater than into deuterons. Maximum neutron energy was shown to be angularly dependent with up to 18 MeV neutrons observed in the forward direction using neutron time-of-flight spectrometry. Absolutely calibrated CR-39 detected spectrally integrated neutron fluence of up to 8x10(exp 8) n sr(exp -1) in the forward direction, Published in the Physics of Plasmas v18 n10 article 10070; published online 24 October 2011. Prepared in collaboration with Naval Research Laboratory, Plasma Physics Division, Washington, DC.

Published
2011

49. Quenching of bcc-Fe from high to room temperature at high-pressure conditions : a molecular dynamics simulation

Author

Belonoshko, Anatoly B., Derlet, P. M., Mikhaylushkin, A. S., Simak, S. I., Hellman, O., Burakovsky, L., Swift, D. C., Johansson, Börje, Belonoshko, Anatoly B., Derlet, P. M., Mikhaylushkin, A. S., Simak, S. I., Hellman, O., Burakovsky, L., Swift, D. C., and Johansson, Börje

Abstract

The new high-temperature (T), high-pressure (P), body-centered cubic (bcc) phase of iron has probably already been synthesized in recent diamond anvil cell (DAC) experiments (Mikhaylushkin et al 2007 Phys. Rev. Lett. 99 165505). These DAC experiments on iron revealed that the high-PT phase on quenching transforms into a mixture of close-packed phases. Our molecular dynamics simulation and structural analysis allow us to provide a probable interpretation of the experiments. We show that quenching of the high-PT bcc phase simulated with the embedded-atom model also leads to the formation of the mixture of close-packed phases. Therefore, the assumption of the stability of the high-PT bcc iron phase is consistent with experimental observation., QC 20100525

Published
2009
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50. Molybdenum at high pressure and temperature : Melting from another solid phase

Author

Belonoshko, A. B., Burakovsky, L., Chen, S. P., Johansson, B., Mikhaylushkin, A. S., Preston, D. L., Simak, S. I., Swift, D. C., Belonoshko, A. B., Burakovsky, L., Chen, S. P., Johansson, B., Mikhaylushkin, A. S., Preston, D. L., Simak, S. I., and Swift, D. C.

Abstract

The Gibbs free energies of bcc and fcc Mo are calculated from first principles in the quasiharmonic approximation in the pressure range from 350 to 850 GPa at room temperatures up to 7500 K. It is found that Mo, stable in the bcc phase at low temperatures, has lower free energy in the fcc structure than in the bcc phase at elevated temperatures. Our density-functional-theory-based molecular dynamics simulations demonstrate that fcc melts at higher than bcc temperatures above 1.5 Mbar. Our calculated melting temperatures and bcc-fcc boundary are consistent with the Mo Hugoniot sound speed measurements. We find that melting occurs at temperatures significantly above the bcc-fcc boundary. This suggests an explanation of the recent diamond anvil cell experiments, which find a phase boundary in the vicinity of our extrapolated bcc-fcc boundary.

Published
2008
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