Probing Liquid Phases and f-Electron Systems at the Dynamic Compression Sector

Project Overview

In this LDRD, the main aim was to develop the first quantitative measurements of the liquid structure factor and radial-distribution function of dynamically compressed materials. The high x ray energy (~ 25 kiloelectron-volts, keV) and high flux at the Advanced Photon Source (APS), coupled to the high energy laser at hutch C of the Dynamic Compression Sector (DCS), are ideally suited to perform these measurements. Experiments at DCS followed initial development of liquid structure determination under shock compression carried out at the Matter in Extreme Conditions (MEC) end-station of the Linac Coherent Light Source (LCLS), using a monochromatic x-ray source with very high flux near 11 keV. Over the three years of the LDRD, liquid scattering data has been collected at both DCS and MEC from dynamically compressed materials. First, shock compression experiments on tin demonstrated the ability to determine the liquid-structure, radial-distribution function and coordination number at extreme compression. The techniques developed were also applied to dynamic compression experiments on selenium, where a liquid–liquid phase transition was identified upon release from the shock-compressed liquid states, the first observation of a liquid–liquid phase transition on nanosecond timescales probed using x-ray diffraction. At DCS, we have developed an analytical approach to correct for pink-beam effects of the 25 keV x-ray source on the liquid scattering measurements, providing the ability to optimize and determine density directly from the x-ray scattering data. We probed the solid/liquid structures of gadolinium on the shock Hugoniot and obtained the liquid structure for an f-electron material, using techniques developed throughout the course of the LDRD. The liquid scattering measurements for gold on the Hugoniot represent an approximately three-fold increase in the maximum pressure that liquid structure has been determined for any material.

Mission Impact

Recently, the National Nuclear Security Administration sponsored the development of the Dynamic Compression Sector (DCS) at the Advanced Photon Source (APS), a user facility dedicated to dynamic compression science. DCS is an exciting and new visionary capability in support of Lawrence Livermore National Laboratory's scientific missions that we have now fully taken advantage of to complete the goals of this LDRD and to lay the foundation and analytical tools to continue important research critical to the Livermore mission goals. A grand challenge within the Stockpile Stewardship Program (SSP) is to develop accurate physical models that cover a wide range of phase space that extend beyond the solid phase space and into regions of dense liquids. A cornerstone of the SSP 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 weapon aging. We have worked closely with simulation groups at Livermore to aid with the validation of the liquid structures explored in this LDRD to help ensure reliable physics models for materials in the dense liquid phase space. The core competency of high-energy-density science (HEDS) aims to provide international leadership in the properties of matter under extreme conditions. The ability to now probe liquid structures in the multi-megabar pressure regimes, as well as the demonstration of the ability to extend liquid structures to the actinides fulfills many of those mission requirements and Livermore is at the forefront of these new experimental capabilities and scientific research areas.

Publications, Presentations, and Patents

Briggs, R., et al. 2020. Measurement of Body-Centered Cubic Gold and Melting under Shock Compression. Physical Review Letters, 123, 45701. LLNL-JRNL-782110.

Briggs, R., et al. 2020. Coordination changes in liquid tin under shock compression determined using in situ femtosecond x-ray diffraction. Applied Physics Letters, 115, 264101. LLNL-JRNL-797485.

Von Dreele, R. B. et al. 2020. "Pink" beam x-ray power diffraction profile and its use in Rietveld refinement. Journal of Applied Crystallography. 54, 1-4. LLNL-JRNL-813585.

Briggs, R. "Probing liquid-liquid phase transitions under dynamic compression: an X-ray diffraction and ab initio MD study of selenium," APS March Meeting, March 2020. (Invited talk) LLNL-PRES-805601.

Briggs, R. "Shock discoveries at X-ray light sources," Hopkins Extreme Materials Institute (HEMI), Johns Hopkins University, October 2019. (Invited talk) LLNL-PRES-804444.

Briggs, R. "Probing liquid-liquid phase transitions under dynamic compression," 7th High Power Laser workshop, SLAC. September 2019. (Invited talk) LLNL-PRES-791621.

Coleman, A.L. "Measurements of Dynamically Compressed Liquid Structure Beyond 3 Mbar Using X-ray Diffraction," 27th AIRAPT International Conference on High Pressure Science and Technology, Rio de Janeiro, August 2019. LLNL-PRES-784805.

Briggs, R. "Liquid-liquid phase transition observed in selenium under dynamic compression using femtosecond X-ray diffraction at LCLS" 27th AIRAPT International Conference on High Pressure Science and Technology, Rio de Janeiro, August 2019. (Invited talk) LLNL-PRES-784870.

Coleman, A.L. "Measurements of Dynamically Compressed Liquid Structure Beyond 3 Mbar Using X-Ray Diffraction,"  21st Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter, Portland, June 2019. LLNL-PRES-777988.

Briggs, R. "First observation of body-centered gold on the shock Hugoniot measured using x-ray diffraction," 21st Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter, Portland, June 2019. LLNL-PRES-777690.