Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session N15: Frontiers of High-Energy Density PhysicsInvited Live Streamed
|
Hide Abstracts |
Sponsoring Units: GSCCM Chair: Peter Celliers, Lawrence Livermore Natl Lab; Ivan Oleynik, University of South Florida Room: McCormick Place W-183C |
Wednesday, March 16, 2022 11:30AM - 12:06PM |
N15.00001: Structural evolution of f-electron systems under dynamic compression Invited Speaker: Sakun Duwal Rare earth, 4f elements play a key role in modern day technological applications, such as computer memories and permanent magnets. Additionally, rare-earth superhydrides have recently been discovered to have near room temperature Tc for superconductors above Mbar pressures. As such, understanding and predicting the material behavior of lanthanides is crucial. This can be done using equation of state information, however, f-electron lanthanides impose a unique challenge in performing first-principles calculations due to their complex electronic and lattice structures. Therefore, experimental equation of state measurements are paramount in providing benchmark data to tightly constrain the ab initio calculations. Here, we present direct evidence of phase transitions and melting along the principle Hugoniot in several lanthanide members using in-situ laser shock diffraction at the Dynamic Compression Sector. |
Wednesday, March 16, 2022 12:06PM - 12:42PM |
N15.00002: Shock compression of statically precompressed low-Z materials Invited Speaker: Yong-Jae Kim For advancing our understanding of the formation, evolution, and interior structure of icy planets (e.g. Uranus and Neptune), we performed accurate experimental measurements of the thermodynamic, optical, and transport properties and chemical bonds of low-Z systems and their mixtures at extreme conditions. To recreate the planetary conditions, static precompression with diamond anvil cells (DACs) is coupled to dynamic compression at laser facilities (Omega, NIF). We studied the shock pressure-density relation of precompressed nitrogen, revealing a gradual evolution in chemical bond; the dissociation of initial molecular nitrogen and L-shell ionization of dissociated atomic nitrogen. We also explored the shock pressure-density-temperature relation and optical property of water and water-based mixtures. Further, we have been developing a new DAC platform on NIF to explore unprecedented extreme conditions. With help from advanced quantum simulations, these results provide a more complete picture of the interior structure of giant planets and strong benchmark for future theoretical developments. |
Wednesday, March 16, 2022 12:42PM - 1:18PM |
N15.00003: Developing direct measurements of temperature and transport properties at hard X-ray FELs Invited Speaker: Emma McBride For extreme states of matter produced in the laboratory, direct and accurate measurements of thermodynamic and transport properties are vital to guide the development of theoretical models. One technique to create such systems is to couple dynamic laser-driven compression and laser heating techniques to access pressure and temperature similar to those found inside the core of planets. While it is possible to directly investigate the density and pressure of a material under dynamic compression, measuring the temperature of the bulk temperature remains a challenge. Common techniques such as streaked optical pyrometry, rely on a priori knowledge of the matter under investigation and give accurate measurements above 4,000 K. In contrast, inelastic X-ray scattering at an X-ray Free Electron Laser offers a unique capability to measure the bulk temperature from low energy collective oscillation of the electron density and the principle of detailed balance. Here, I will discuss the method and its validation from measurements taken at the High Energy Density end station at the European XFEL on resistively heated single crystal Diamond. Finally, I will present the application of this method to measure the ion temperature of shock compressed argon at the Matter in Extreme Condition at the Linac Coherent Light Source. |
Wednesday, March 16, 2022 1:18PM - 1:54PM |
N15.00004: Megajoule fusion yield produced from inertial fusion implosions at the National Ignition Facility Invited Speaker: Alex B Zylstra Thermonuclear fusion in the laboratory is a scientific grand challenge, a highly compelling problem because the fusion reactions can self-heat the fuel and continue the burn. Predominantly approaches use the fusion of deuterium and tritium nuclei, which generates 17.6 MeV of energy released in a neutron and alpha particle. The alpha particle, which carries 1/5 of the energy, can heat the plasma. A plasma in which the alpha self-heating is greater than external heating is termed a 'burning plasma', and one in which the self-heating dominates over all loss mechanisms, leading to a run-away increase in temperature, is termed 'ignited'. Inertial confinement fusion (ICF) has pursued these scientific milestones using large laser drivers, notably the National Ignition Facility (NIF) at LLNL. Here we use the laser energy, up to 1.9MJ, to generate a hot x ray bath, which creates ablation pressures of hundreds of Mbar at the outer surface of a fuel-containing capsule. The ablation pressure implodes the capsule, with fuel pressures of several hundred GBar generated as the fuel stagnates at the center. The combination of these extreme pressures and inertial confinement times from the surrounding material can lead to burning and ignited plasmas. Recent experiments on NIF in the last year have generated 25x higher fusion yields than previous records, up to 1.3MJ. The physical basis for this increase in performance relative to previous NIF results, as well as the scientific implications, will be discussed. The substantially higher level of fusion self-heating in these plasmas generates unprecedented conditions for experiments in the laboratory. |
Wednesday, March 16, 2022 1:54PM - 2:30PM |
N15.00005: Exploring metallic and superionic ammonia in ice giant interiors Invited Speaker: Alessandra Ravasio Mixtures of water, ammonia and methane are predicted to be the major components in the depths of the ice giant planets Uranus and Neptune. Their dynamics, evolution, and interior structure are insufficiently understood and models rely imperatively on data for equations of state and transport properties. The physical and chemical behavior of such systems at the extreme pressures and temperatures of planetary interiors is also extremely interesting on its own, since those conditions are characterized by a coexistence of dissociated atoms, atomic clusters, chains and superionic lattices. In spite of its great appeal, exploring these phenomena is a real challenge for both ab initio calculations and experiments so that dedicated studies remain very limited. Here we present our recent work obtained combining laser-driven shock experiments and state-of-the-art density functional theory molecular dynamics (DFT-MD) simulations, focusing on ammonia. We investigate the equation of state, the melting line, the optical properties and the electrical conductivity over a wide range of pressure and temperature conditions. We find experimental evidence of metallic ammonia, through a gradual transition from a liquid dominated by molecules to a plasma state at ~7000 K and 90 GPa. Shock compression of ammonia in solid phase III allows us to observe the melting of superionic ammonia between 70 and 125 GPa. The melting line is subsequently further constrained with DFT-MD up to 275 GPa and 4500K. The reflectivity data provide the first experimental evidence of electronic conduction in high pressure ammonia and are in excellent agreement with the reflectivity computed from atomistic simulations. Corresponding electrical conductivity values are found up to one order of magnitude higher than in water at conditions relevant to pertinent interior models, with possible implications on the generation of magnetic dynamos in large icy planets' interiors. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700