Department of Chemistry Seminar: Multi-platform experiments studying materials under extreme compression
About the event
Presenter: Dr. Sakun Duwal
Host: Choong-Shik Yoo
Title: Multi-platform experiments studying materials under extreme compression
Abstract: Studying materials at extreme conditions is not only relevant to nuclear weapon conditions, but also to planetary interiors. Highly accurate equation of state data at extreme conditions provides a solid basis for models that enable predictive simulation of material properties. In this talk, I will cover the investigation of two different material categories at extreme conditions: pre-compressed H2-He gas-mixtures and lanthanides. Studying pre-compressed samples of H2-He mixtures under dynamic loading allows us to access unique P-T states off of the principal Hugoniot. The understanding of material behavior at these P-T states is crucial to comprehend the origin and evolution of gas planets. Furthermore, the validation of mixture models has been a long-standing topic of interest with numerous conflicting theoretical results, particularly for non-ideal hydrogen systems. In this talk, I’ll present the experimental results on the pre-compressed samples of H2-He mixtures using pulsed-power-driven flyer plates at the Sandia Z-facility, and impact studies on the two-stage light gas gun. The second portion of the talk will focus on the phase transitions and melting during the dynamic x-ray diffraction using the Dynamic Compression Sector, and temperature measurements on two different lanthanides members, Sm and Gd. This study highlights the underlying challenges and issues with melting studies and measuring temperature measurements under real-time conditions.
Bio: Sakun Duwal received her Ph.D. in Physical Chemistry in May 2018 from Washington State University, under the supervision of Prof. Choong-Shik Yoo. While at WSU, she studied chemistries of sulfides, azides, and oxides, and gained expertise in high-pressure spectroscopy and diffraction using light sources at APS in Argonne National Laboratory and SPring-8 in Japan. In August of 2018, she took a position as a Postdoctoral Appointee at Sandia National Laboratories in Albuquerque, NM. In 2019, she was converted to her current position as a Staff Scientist. Sakun leads the pre-compression studies of gas-mixtures at Sandia’s Z-machine and hyper velocity gas-guns. Sakun has pioneered multi-platform methods to study phase transitions and phase transition kinetics, including melting during dynamic compression. At Sandia, Sakun has expanded her abilities to include proficiency in laser shock experiments at the OMEGA facility at the University of Rochester, National Ignition Facility (NIF) and dynamic x-ray scattering at the Dynamic Compression Sector (DCS) at Argonne National Laboratories.