Unraveling the Physics and Chemistry of Water-Rich Mixtures at Extreme Pressures and Temperatures

Project Overview

Our understanding of the formation and evolution of the solar system has been recently completely reshuffled by the discovery of a broad variety of extra-solar planetary systems which could not be explained by existing models. To build better planetary models that can match all existing observations (e.g. gravity and magnetic fields and planet luminosity), we need to understand how the constituent materials behave at the extreme conditions of pressure P (up to several TPa) and temperature T (several thousand K) inside large planets. The study of multicomponent systems at the relevant extreme P-T conditions has been out of reach for both experiments and first-principles numerical simulations for several decades due to the inability to produce high-compression states of planetary ices and to couple those conditions with insightful probes.

We developed three new, laser-driven, dynamic compression platforms, as well as unique sample preparation and metrology systems. We first coupled diamond anvil cells (DACs) and decaying shock calorimetry at both the Omega and National Ignition Facility (NIF) laser facilities. This enabled us to obtain equation of state (EOS) and optical property data to document the structure and bonding changes at the macroscopic and atomic scales in water-rich H2O-CH3OH-NH3 mixtures representative of the interior of Neptune and Uranus. We also successfully developed a new, highly reliable dynamic x-ray diffraction platform at the Omega EP laser and collected new data to document the atomic structure and the kinetics of crystallization of water ices at unprecedented extreme pressure and temperature conditions. Finally, we also developed a new Diamond Anvil Cell shock platform at the NIF paving the way towards news EOS and conductivity measurements at unprecedented conditions. In parallel, we launched a new collaborative effort to develop new large scale computer simulations using machine learning to reveal the atomic scale origin of macroscopic property changes. These new transformational capabilities will enable us for the first time to decipher the macroscopic thermodynamic properties of planetary constituents and understand their miscibility and phase changes.

Mission Impact

This LDRD successfully contributes new technology tools and capabilities to meet future national security challenges. We developed novel experimental techniques and computer models that probe gaseous and liquid systems applicable to enhance the fundamental understanding of aging nuclear weapons systems.

A corner stone of Stockpile Stewardship is a continued demonstration of our advanced understanding of simulations and applications of scientific knowledge to specific problems of weapons performance, Life Extension Programs and weapons aging. The advanced experimental techniques we developed at state-of-the-art facilities such as the NIF will contribute to expand LLNL and NNSAs focus on advancing our expertise in weapons science and sustained confidence in the nation's nuclear deterrent. The development of x-ray diffraction experiments to study the phase and EOS of fluids is relevant to the first Key Area of Interest on First Principles Understanding of Fundamental Science of the Mission Research Challenge on Nuclear Weapons Science. Since the physics of chemical segregation at the warm dense matter conditions within icy planets is analogous to the kinetics of carbon condensation in a detonating high explosive, our project also aligns well with the new Mission Research Challenge on High Explosive Physics, Chemistry, and Material Science. Finally, the recruitment of several staff scientists, the training of students and the development of a new international collaboration on machine-learning computer simulations also participate to the core competency of High-Energy-Density-Science (HEDS) goal to provide international leadership in the properties of matter under extreme conditions.

Publications, Presentations, and Patents

Reinhardt, A., M. Bethkenhagen, F. Coppari, M. Millot, S. Hamel, and B. Cheng. "Thermodynamics of High-Pressure Ice Phases Explored with Atomistic Simulations." Nat Commun 13, no.1 (2022): 4707. https://doi.org/10.1038/s41467-022-32374-1.

Kim, Y. J., B. Militzer, B. Boates, S. Bonev, P. M. Celliers, G. W. Collins, K. P. Driver, et al. "Evidence for Dissociation and Ionization in Shock Compressed Nitrogen to 800 Gpa." Phys Rev Lett 129, no.1 (2022): 015701. https://doi.org/10.1103/PhysRevLett.129.015701.

Wadas, Michael J., Griffin Cearley, Jon Eggert, Eric Johnsen, and Marius Millot. "A Theoretical Approach for Transient Shock Strengthening in High-Energy-Density Laser Compression Experiments." Physics of Plasmas 28, no. 8 (2021): 082708. https://doi.org/10.1063/5.0055414.

Kim, Y. J., P. M. Celliers, J. H. Eggert, A. Lazicki, and M. Millot. "Interferometric Measurements of Refractive Index and Dispersion at High Pressure." Sci Rep 11, no. 1 (2021): 5610. https://doi.org/10.1038/s41598-021-84883-6.

Cheng, Bingqing, Mandy Bethkenhagen, Chris J. Pickard, and Sebastien Hamel. "Phase Behaviours of Superionic Water at Planetary Conditions." Nature Physics 17, no. 11 (2021): 1228-32. https://doi.org/10.1038/s41567-021-01334-9.

Brygoo, S., P. Loubeyre, M. Millot, J. R. Rygg, P. M. Celliers, J. H. Eggert, R. Jeanloz, and G. W. Collins. "Evidence of Hydrogen-Helium Immiscibility at Jupiter-Interior Conditions." Nature 593, no. 7860 (2021): 517-21. https://doi.org/10.1038/s41586-021-03516-0.

Millot, Marius, Shuai Zhang, Dayne E. Fratanduono, Federica Coppari, Sebastien Hamel, Burkhard Militzer, Dariia Simonova, et al. "Recreating Giants Impacts in the Laboratory: Shock Compression of Bridgmanite to 14 Mbar." Geophysical Research Letters 47, no. 1 (2020): e2019GL085476. https://doi.org/10.1029/2019gl085476.

Crandall, L. E., J. R. Rygg, D. K. Spaulding, T. R. Boehly, S. Brygoo, P. M. Celliers, J. H. Eggert, et al. "Equation of State of CO2 Shock Compressed to 1 Tpa." Phys Rev Lett 125, no. 16 (2020):165701. https://doi.org/10.1103/PhysRevLett.125.165701.