THE INSTITUTE FOR SHOCK PHYSICS Understanding Materials at Extreme Dynamic Compression

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1 THE INSTITUTE FOR SHOCK PHYSICS Understanding Materials at Extreme Dynamic Compression Yogendra M. Gupta Washington ate University Acknowledgements: 1. DOE/NNSA support 2. D. Lacina, M. Winey, M. Lucas, J. Hawreliak Presented at the SSAP Symposium Santa Fe, NM March 11,

2 Background Representative Scientific Activities Outline Multiply shocked liquid nitrogen molecular response Beryllium single crystals shock wave propagation: anisotropy effects Shock compressed HOPG acoustic measurements Warm dense matter research: plans for the future (Professor J. Hawreliak) Path Forward 2

3 Mission Institute Mission and Research Thrusts Innovative and exciting science Rigorous education and hands-on training Meaningful interactions with the NNSA Laboratories Research Thrusts (Condensed Matter) Phase Changes and EOS Chemical reactions and HE decomposition Inelastic deformation and fracture Novel developments and out-of-the-box thinking Address SSP needs by combining innovative science, rigorous education, and programmatic relevance 3

4 Institute s Scientific Theme and Approach Continuum-to-atomic scale understanding of the response of materials to extreme conditions: Multidisciplinary research (physics, chemistry, materials science, mechanics) to address relevant phenomena Fundamental understanding through real-time measurements at different length scales Novel experimental developments atic pressure research to complement shock work Warm dense matter; academic effort initiated Theory/computations at different length scales Understanding dynamic material response through real time, multiscale measurements and analysis 4 4

5 Major Research Facilities Impact Laboratory atic High Pressure Laboratory Theory and Computations Laser Shock Laboratory Pulsed Power Facility 5

6 Graduate udents (CY2014) Physics (4) Education and Outreach Mechanical Engineering (3) Materials Science (3) Chemistry (2) Involvement of Undergraduate udents Educational Collaboration Los Alamos (Dr. Ellen Cerreta) Summer Undergraduate Research Experience: Materials Under Extreme Conditions 10-week exposure to hands-on research, Physics, and Mechanical Engineering faculty mentors Physics 592 Course: Fundamentals of Shock Wave Propagation (Fall 2013); 43 Scientists from the NNSA Laboratories 6

7 Multiply Shocked Liquid Nitrogen Molecular response of liquid nitrogen previously examined at high and low temperatures High temperatures promote chemical changes in singly shocked liquid nitrogen Single Single Shock Shock Double Double Shock Shock This Work No nitrogen EOS to provide calculated temperatures Objective: atic atic atic atic Comprehensive description of HP-HT liquid nitrogen response, including region between static and single/double shock data Approach: Raman spectroscopy of multiply shocked liquid nitrogen to determine Raman shift and temperature Impactor atic LN 2 Front Window atic atic atic Laser Back Window Raman atic 7

8 Raman Shifts in Shocked LN Raman shifts measured for multiply shocked liquid nitrogen Comparison with previous measurements Liquid nitrogen response depends on pressure and temperature conditions Pressure and temperature play competing roles Description of Raman shift as a function of pressure and temperature Raman Shift = ω 0 + A*P + B*P 2 + C*T + D*T 2 Molecular response determined using P-T dependence of Raman shifts 8

9 Nitrogen Response at Different P-T Conditions Molecular response depends on temperature range Below 1500K: Bond strengthening due to high pressure K: Single Shock Double Shock Bond strengthening reduced by temperatureinduced bond weakening Above 4000K: Bond weakening despite compression at high pressure atic atic This Work atic atic atic Temperature measurements central to understanding HP-HT response Multiply shocked liquid nitrogen remains a molecular fluid Lacina and Gupta, JCP (2014) 9

10 Shocked Single Crystals: Low Symmetry Directions Single crystal experiments enable selective activation of inelastic deformation mechanisms Be single crystal ( ) ( 1012) c-axis 1122 Wave profiles for low symmetry directions are rich in mechanistic information Numerical simulations using anisotropic modeling framework required Case udy Shocked beryllium single crystals Approach a-axis low symmetry directions Shock wave compression VISAR Analyze measured wave profiles using anisotropic modeling framework [Winey and Gupta, JAP (2006)] Impactor Be Single Crystal VISAR Window Pope & evens (1973); Pope & Johnson (1975) 10

11 Shocked Be Single Crystals Previous measurements Seven crystal orientations Peak stresses from 1 7 GPa Multiple inelastic deformation mechanisms not accounted for in previous analysis Pope & evens (1973); Pope & Johnson (1975) Calculated results for a-axis compression Good overall match to measured wave profiles ( ) 1012 twinning needed to relax σ σ stress difference xx zz Both prismatic slip and deformation twinning contribute to inelastic deformation a-axis 11

12 Shocked Be: Low Symmetry Directions 46 deg. from c-axis Complex response: wave mode coupling due to highly anisotropic inelastic response Primary mechanism is basal slip Prismatic slip needed to relax stress difference σ Importance of prismatic slip and twinning grows with increasing angle from c-axis σ xx Key insight from shock compression along low symmetry directions yy Winey and Gupta, JAP (2014) 12

13 What is Warm Dense Matter? WDM occurs at the intersection of condensed matter and plasma physics Too hot to be condensed matter Too strongly coupled to be a plasma Hot enough that a large fraction of electrons are excited above the Fermi energy Murillo, M. S. Physics of Plasmas 11, 2964 (2004). warm dense matter is a malfunction junction that lies at the confluence of plasma, gas, liquid and solid... -Basic Research Needs for High Energy Density Laboratory Physics, Nov

14 Why udy WDM? It inspires our imagination WDM is a fertile ground for academic research: Newly discovered exoplanets, Solar system formation, Properties of giant planets, Pathways to achieving fusion energy 17

15 Exploring WDM using ate-of-the-art Facilities The focus at will be to span the length and timescales associated with WDM using stateof-the-art capabilities X-ray scattering to investigate ion and electron structure X-ray imaging to investigate dynamic properties NIF Conventional Shock techniques to investigate constitutive properties Z-Machine Ω/Ω EP MEC / LCLS DCS@APS 18

16 Institute for Shock Physics: Path Forward Continue as a national model for integrating scientific excellence, education, and strategic national interests in dynamic compression science Encourage scientific curiosity and risk taking Educate and train outstanding graduate and undergraduate students, and postdocs Interact with the DOE/NNSA Labs. to stay abreast of national priorities 19