Bulletin of the American Physical Society
22nd Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 67, Number 8
Monday–Friday, July 11–15, 2022; Anaheim, California
Session L03: Platform DevelopmentFocus Recordings Available
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Chair: Minta Akin, Lawrence Livermore Natl Lab Room: Anaheim Marriott Platinum 1 |
Tuesday, July 12, 2022 2:00PM - 2:30PM |
L03.00001: Compressing Pre-Compressed Hydrogen-Helium Mixtures using Z-Machine and Hypervelocity Gas-Guns Invited Speaker: Sakun Duwal Hydrogen and helium are the most abundant elements in the universe. Understanding the properties of hydrogen-helium mixtures is essential to study the origin and structural evolution of Jovian planets. However, the equation of state of hydrogen-helium mixtures remains ill determined. While there has been extensive theoretical work on the phase diagram relevant for H+He demixing, there are to date few experimental studies exploring this important, yet, ill-determined region of the H+He equation of state. Here, we have measured the equation of state of pre-compressed hydrogen-helium (H2-He) mixtures using hypervelocity gas-guns and Sandia’s Z machine up to 86 GPa. We pre-compressed 50:50 molar mixtures of H2-He to 0.1 -0.2 GPa using a sapphire anvil cell. We directly measured particle velocity (in gas-gun experiments) and shock velocities (in Z-machine experiments). To complement experimental efforts, we have also computed the Hugoniots of pre-compressed hydrogen-helium samples using density functional theory based molecular dynamics. The current Hugoniot data can be used to distinguish between the proposed controversial mixing models. |
Tuesday, July 12, 2022 2:30PM - 2:45PM |
L03.00002: High pressure platform development for the Z Machine: compression of platinum to 650 GPa Andrew J Porwitzky, Justin L Brown, Sakun Duwal Effort in recent years has succeeded in developing a new high pressure, low uncertainty ramp compression platform for the Z Machine that is capable of driving high impedance materials to pressures approaching those achievable on the National Ignition Facility (NIF). Bayesian uncertainty quantification (UQ) techniques on a recent platinum experiment indicate that density uncertainties are less than 2% at 650 GPa. The peak pressure analyzed on this new platform is over 80% of the pressure recently achieved in platinum on NIF. We will discuss advances that made the platform realizable as well as UQ techniques employed. |
Tuesday, July 12, 2022 2:45PM - 3:00PM |
L03.00003: Laser-Driven Plate Impact Technique with Application to Al6061-T6 HEL, Spall, and EOS Isaias Chocron, Frederick M Heim, Thomas Z Moore, Roberto Enriquez-Vargas, Matt Barsotti, Eddie O'Hare, David Stevens Following work performed by the Dlott team (see, among others, [1]–[3]) and also recently by Mallick ([4]–[6]), Southwest Research Institute and Protection Engineering Consultants teamed to design and build a laser-driven plate-impact facility that allows obtaining Hugoniot Elastic Limit, spall stress, and equation of state for different materials. Although the system is in general terms similar to Dlott’s and Mallik’s, several improvements were implemented to obtain more consistent and clear signals, as well as increase throughput. The following differences are highlighted: 1) Sighting system using camera and software to precisely aim with the driving laser at the flyer, 2) System that allows precise alignment of PDV probe, flyer, and driving laser, 3) New algorithm to automatically analyze spectrograms. |
Tuesday, July 12, 2022 3:00PM - 3:15PM |
L03.00004: Design and first tests of an electrically-driven exploding foil hypervelocity launcher for study of material behaviour at Mbar conditions Mila Fitzgerald, James Pecover, Daniel Eakins, Nik Petrinic The conditions experienced by spacecrafts, lunar habitats and fusion reactors, to name a few examples, are unlike any found naturally on the earth's surface. The selection and design of resilient materials for such purposes therefore requires controlled access to these conditions, which in turn relies upon advancement of techniques to generate ever higher material pressures and temperatures. The electric gun projectile launcher is one such technique, which utilizes the rapid expansion of an ohmically heated exploding foil to accelerate thin flyers above 20 km/s. Though the launcher has the potential to access a largely unexplored thermodynamic space, the process of launching flyers above 0.25 mm thickness in this manner is highly variable, often resulting in uncontrolled launch characteristics and premature failure of the flyer. This behavior is challenging to diagnose experimentally, limiting the validation of numerical models and leaving uncertainties in material properties unresolved. This work presents the novel modelling, design, and experimental testing of the highest energy electric gun load in the world, powered by a 2.5 MJ capacitor bank. Preliminary results reveal the successful and repeatable launch of a 0.5 mm thick polymer flyer into a PMMA target block, generating impact pressures of 80 GPa. This advancement marks a stepping-stone towards optimizing the electric gun to achieve even higher pressures and shock durations, enabling it to probe a material phase space inaccessible to alternative projectile launchers. |
Tuesday, July 12, 2022 3:15PM - 3:30PM |
L03.00005: Shock Release Experiments (SRE) platform development for JASPER Yekaterina Opachich, Pat W Ambrose, Jeff H Nguyen, Stephen Sippel, Paul Benevento, Taren J Bowen, Jeff Cates, Elijah M Chamberlin, Pat Dohoney, John P Dressler, Dezi A Hatch, Russell A Howe, Michelle C Hawkins, Chan Hon Jung, Mark A Krubsack, James B Majdanac, Melissa Matthes, Dane C Ramos, Eduardo Rodriguez, Robert Shelton, Todd L Ware, Elida White, Sam Williams, Dayne E Fratanduono, Ricky Chau The Shock Release Experiments (SRE) platform on the Joint Actinide Shock Physics Experimental Research (JASPER) facility has been developed to investigate the off-Hugoniot release path of metals that are shocked to high pressure using plate impact. This simple and direct measurement provides a release isentrope of a shocked sample in a single experiment. The release path is determined by measuring the free surface velocity of six witness materials of lower impedance. We present the details of the shock release platform, and an example of the release behavior of tantalum. |
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