Bulletin of the American Physical Society
21st Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 64, Number 8
Sunday–Friday, June 16–21, 2019; Portland, Oregon
Session O6: GPS: Improving equations of state and models |
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Chair: June Wicks, Johns Hopkins University Room: Broadway III/IV |
Wednesday, June 19, 2019 11:00AM - 11:30AM |
O6.00001: Physics of matter at extreme conditions: insights from quantum mechanical calculations Invited Speaker: Shuai Zhang Knowledge about structures and properties of matter at high pressure, temperature conditions are extremely important for understanding planetary interiors, simulating post-giant impact processes, and the design and interpretation of high-energy-density (HED) experiments. By means of quantum mechanical calculations, we study chemical bond dissociation, phase transformation, and equations of state in representative materials or rock-forming minerals under dynamic compression. We characterize the physical processes from the atomistic and electronic levels, compare our findings with experiments and previous calculations, quantify fidelity of the results, and discuss implications for planetary and HED sciences. This is an effort toward unambiguous elucidation of extreme physics. [Preview Abstract] |
Wednesday, June 19, 2019 11:30AM - 11:45AM |
O6.00002: Iron Equation of State Measurements on the Z-Machine Sean Grant, Tommy Ao, Aaron Bernstein, Jean-Paul Davis, Todd Ditmire, Jung-Fu Lin, Andrew Porwitzky, Christopher Seagle We have measured the equation of state of iron along an elevated quasi-isentrope from 275 GPa to 400 GPa, reaching pressure and temperature conditions similar to the core of the Earth. This is enabled by the shock-ramp capability at Sandia National Laboratory's Z machine, a pulsed power facility which can probe off-Hugoniot P-T regions by shocking a material and subsequently driving a further shockless compression. The resulting unique parameter space is lower in temperature than a shock Hugoniot, but higher than the primary isentrope. We derive the EOS using an iterative backward integration -- forward Lagrangian technique on particle velocity traces from symmetrically-loaded sample pairs of differing thicknesses. Sandia National Labs is managed and operated by National Technology {\&} Engineering Solutions of Sandia, LLC, a subsidiary of Honeywell International, Inc., for the U.S Dept. of Energy's National Nuclear Security Administration under contract DE-NA0003525. SAND2019-1631 A [Preview Abstract] |
Wednesday, June 19, 2019 11:45AM - 12:00PM |
O6.00003: Global equation of state of a reactive, polyatomic system: application to carbon dioxide Philip C. Myint, Christine J. Wu, David A. Young, Philip A. Sterne An important topic in high-energy-density science involves developing a global equation of state (EOS) that spans a wide range of pressures and temperatures. One notorious challenge in building a global EOS is the inclusion of chemistry, yet this is essential for modeling many dissociative materials for which the chemical reactions constitute a sizable contribution to the total free energy. We present an EOS for carbon dioxide (CO$_2$) that accounts for dissociation by capturing the key physics/chemistry present in several relevant pressure--temperature regimes and interpolating between the regimes over the global range in pressure and temperature. We have extended the dissociation methodology proposed by Young and Corey over 25 years ago for diatomic molecules to polyatomic molecules. We use CO$_2$ as a prototypical polyatomic system, since it is one of the simplest molecular systems beyond diatomic materials, and since a CO$_2$ EOS would be useful for many applications, including organic synthesis, geochemistry, volcanism, and planetary interiors. We show that while there is still much room for further improvement, taking dissociation into account significantly improves the accuracy of the EOS compared to other global equations of state for CO$_2$ that neglect chemistry. [Preview Abstract] |
Wednesday, June 19, 2019 12:00PM - 12:15PM |
O6.00004: Dynamic Properties of Dragonshield BC\texttrademark , Polyurea 650, and Polyurea 250/1000 Lauren Edgerton, Susan Bartyczak, Willis Mock, Jeffry Fedderly, Edward Balizer A 40 mm bore gas gun was used to investigate the shock response of two viscoelastic polymer materials: Dragonshield BC$^{\mathrm{TM}}$, Versathane P650, and a blend of Versathane P250 and P1000. Sabots carrying Al or Cu metal disks were launched into target assemblies containing the polymer material. The target consisted of a thin metal disk on the impact side, a 6.5-mm-thick polymer disk, and a thick metal backup disk. 50 ohm manganin gauges were epoxied between the metal/polymer and polymer/metal interfaces to measure the interface stresses and shock transit time. Measured longitudinal stresses ranged from 2.9 to 34.8 kbar. The interface particle velocity, shock velocity, mean stress, and uniaxial strain were calculated for each experiment. The experimental technique, analysis methodology, and results will be presented. [Preview Abstract] |
Wednesday, June 19, 2019 12:15PM - 12:30PM |
O6.00005: Multiple shock reverberation compression of dense Ne up to the warm dense regime: Evaluating the theoretical models Qi-Feng Chen, Jun Tang, Yun-Jun Gu, Jun Zheng, Cheng-Jun Li, Yu-Feng Wang, Zhi-Guo Li Knowledge of thermodynamic properties of materials in warm dense matter (WDM) regime is especially important for understanding many high-energy density physics processes and phenomena, such as the interior structure of the earth, inertial confinement fusion, and the formation and evolution of gaseous giants. Neon is the primary constituent of planetary and stellar atmospheres. Its thermodynamic properties in WDM region are vital to construct the inner structure of these astrophysics objects and understand their formation and evolution. In this work, multiple shock reverberation compression experiments are designed and performed to determine the equation of state of neon ranging from the initial dense gas up to the warm dense regime where the pressure is up to 120 GPa and the temperature is up to above 20000 K. The wide region experimental data are used to evaluate the available theoretical models. It is found that, for neon below 1.1g/cm$^{\mathrm{3}}$, within the framework of density functional theory molecular dynamics, a van der Waals correction is meaningful. Under high pressure and temperature, results from the self-consistent fluid variational theory model are sensitive to the potential parameter. The new observations on neon under megabar pressure and 10$^{\mathrm{4}}$ K temperature enrich the understanding on properties of warm dense matter and have potential applications in revealing the formation and evolution of gaseous giants or mega-Earths. [Preview Abstract] |
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