Benchmarking boron carbide equation of state using computation and experiment

Journal Article · Tue Nov 03 00:00:00 EST 2020 · Physical Review. E

DOI:https://doi.org/10.1103/physreve.102.053203· OSTI ID:1775037

Zhang, Shuai  ^[1]; Marshall, Michelle C.  ^[2]; Yang, Lin H. ^[2]; Sterne, Philip A. ^[2]; Militzer, Burkhard ^[3]; Däne, Markus  ^[2]; Gaffney, James A. ^[2]; Shamp, Andrew ^[2]; Ogitsu, Tadashi ^[2]; Caspersen, Kyle ^[2]; Lazicki, Amy E. ^[2]; Erskine, David  ^[2]; London, Richard A. ^[2]; Celliers, Peter M. ^[2]; Nilsen, Joseph ^[2]; Whitley, Heather D. ^[2]

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1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of Rochester, NY (United States). Lab. for Laser Energetics
2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
3. Univ. of California, Berkeley, CA (United States)

Boron carbide ( ${\mathrm{B}}_4\mathrm{C}$) is of both fundamental scientific and practical interest due to its structural complexity and how it changes upon compression, as well as its many industrial uses and potential for use in inertial confinement fusion (ICF) and high-energy density physics experiments. Here, we report the results of a comprehensive computational study of the equation of state (EOS) of ${\mathrm{B}}_4\mathrm{C}$ in the liquid, warm dense matter, and plasma phases. Our calculations are cross-validated by comparisons with Hugoniot measurements up to 61 megabar from planar shock experiments performed at the National Ignition Facility (NIF). Our computational methods include path integral Monte Carlo, activity expansion, as well as all-electron Green's function Korringa-Kohn-Rostoker and molecular dynamics that are both based on density functional theory. We calculate the pressure-internal energy EOS of ${\mathrm{B}}_4\mathrm{C}$ over a broad range of temperatures ( $~6\times {10}^3$– $5\times {10}^8$ K) and densities (0.025–50 $\mathrm{g}/{\mathrm{cm}}^3$). We assess that the largest discrepancies between theoretical predictions are $\lesssim 5\%$ near the compression maximum at 1– $2\times {10}^6$ K. This is the warm-dense state in which the K shell significantly ionizes and has posed grand challenges to theory and experiment. By comparing with different EOS models, we find a Purgatorio model (LEOS 2122) that agrees with our calculations. The maximum discrepancies in pressure between our first-principles predictions and LEOS 2122 are $~18\%$ and occur at temperatures between $6\times {10}^3$– $2\times {10}^5$ K, which we believe originate from differences in the ion thermal term and the cold curve that are modeled in LEOS 2122 in comparison with our first-principles calculations. To account for potential differences in the ion thermal term, we have developed three new equation-of-state models that are consistent with theoretical calculations and experiment. We apply these new models to 1D hydrodynamic simulations of a polar direct-drive NIF implosion, demonstrating that these new models are now available for future ICF design studies.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344; SC0016248
• OSTI ID: 1775037
• Report Number(s): LLNL-JRNL-812984; 1020196; TRN: US2209296
• Journal Information: Physical Review. E, Vol. 102, Issue 5; ISSN 2470-0045
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
equations of state
high-energy-density plasmas
plasma ionization
shock waves
hot dense plasma
warm-dense matter
density functional calculations
path-integral Monte Carlo