Bulletin of the American Physical Society
64th Annual Meeting of the APS Division of Plasma Physics
Volume 67, Number 15
Monday–Friday, October 17–21, 2022; Spokane, Washington
Session CO06: HEDP Laboratory AstrophysicsLive Streamed
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Chair: Hye-Sook Park, LLNL Room: Ballroom 111 C |
Monday, October 17, 2022 2:00PM - 2:12PM |
CO06.00001: Results from X-ray Opacity Experiments on the National Ignition Facility (NIF) Theodore S Perry, Robert F Heeter, Heather M Johns, Yekaterina P Opachich, Evan S Dodd, Natalia S Vinyard, Thomas H Day, Christopher J Fontes, Lynn Kot, Peter Hackel, Todd J Urbatsch, Brian G Wilson, Eric C Dutra, Matthew S Wallace, James M Heinmiller, Daniel C Mayes, Donald E Winget, Michael H Montgomery, Enac Gallardo Diaz, James E Bailey Since 2015 experiments on the NIF have been investigating the x-ray opacities that are used in the radiation-hydrodynamic simulations of the sun, stars, and other high-energy-density plasma. There is little spectrally resolved, experimental opacity data of plasma at the temperatures and densities involved in these calculations. Recent opacity experiments on the Sandia National Laboratories Z machine have shown up to factors of two discrepancies between theory and experiment. At NIF initial opacity data has been taken on iron and oxygen at temperatures around 150 eV and densities around 1022 electrons/cc. Like the Z opacity experiments, our preliminary data seem to indicate discrepancies between the measured and the theoretical opacities, but additional data analysis is needed to correct for known instrumental effects. This data may have implications for modeling the structure of the sun and for determining the age of white dwarf stars. |
Monday, October 17, 2022 2:12PM - 2:24PM |
CO06.00002: Mix Effects in Opacity-on-NIF Samples Ethan Smith, Todd J Urbatsch, Natalia Krasheninnikova Opacity-on-NIF uses layered targets to measure the x-ray transmission opacity on National Ignition Facility (NIF). Mix between different layers can alter target's opacity by increasing the width of the foil thus decreasing its density. Several mix models of the target foil and tamping material are considered alongside an unmixed and a homogeneously mixed case. The ability of the target to reach sufficient temperatures and densities and remain uniform and in local thermal equilibrium is evaluated. The effects of mix on the transmission opacity are quantified as a function of mix width and compared with experimental observations. |
Monday, October 17, 2022 2:24PM - 2:36PM |
CO06.00003: Use of MERL for Stark-broadening Analysis on Opacity-on-NIF Heather M Johns, Robert F Heeter, Theodore S Perry, Yekaterina P Opachich, David P Kilcrease, Roberto C Mancini, Eric C Dutra, Matthew S Wallace, Evan S Dodd, Natalia Krasheninnikova, Richard A London, Manolo Sherrill, Brian G Wilson, Carlos A Iglesias, Thomas H Day, Todd J Urbatsch, Sean M Finnegan, Taisuke Nagayama, Gregory A Rochau The Opacity-on-NIF campaign1,2 measures transmission to provide opacity data for Fe and other elements to help address the discrepancy between theory and Opacity-on-Z data3. The Opacity-on-NIF experiments have worked to improve reproducibility and correct for backgrounds, and have reached the point where comparison to Stark broadened line shapes4 (using MERL) can become reliable for extracting areal density. This can be compared to areal density from sample expansion measurements5,6,7. While an initial analysis has been previously shown, comparison to data at different stages of corrections will illustrate improved accuracy.
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Monday, October 17, 2022 2:36PM - 2:48PM |
CO06.00004: Radiographic studies of a shockwave interacting with a counter-propagating radiation flow Pawel Kozlowski, Heather M Johns, Shane X Coffing, Tom Byvank, Chris L Fryer, Christopher J Fontes, Harry F Robey, Suzannah R Wood, Andy S Liao, David D Meyerhofer, Todd J Urbatsch The Radishock platform studies the interaction between a radiation wave, produced via a halfraum, and a counter-propagating shockwave, produced via a directly driven ablator, within a Ti-laden silica aerogel foam. These experiments can provide insight into supernova shock breakout emission where the radiation flow breaking out of the star interacts with the circumstellar medium and the relative velocity between this breakout and the medium dictates the degree of heating in the shock. In our Radishock experiments, the radiation flow is not apparent in the radiographic diagnostic and can be directly observed only via the absorption spectroscopy diagnostic, which provides a measure of temperature and position. On the other hand, the shockwave launched from the ablator side of the target is observed in the radiographs, and we extract the full 2D shock front contour using computer vision techniques. In the course of this analysis, we found features present in the late time interaction shots which were not present in the radiation wave only, shockwave only, and early time interaction shots. These features appear to be a reflection of the shockwave off of the radiation front, and would provide an indirect means of probing the radiation wave radiographically. |
Monday, October 17, 2022 2:48PM - 3:00PM |
CO06.00005: Strongly coupled, radiative shock experiments on the Omega-60 laser facility relevant to type Ia supernova and neutron star envelopes Heath J LeFevre, Scott D Baalrud, Carolyn C Kuranz Compact objects are some of the most extreme environments in nature. The experiments described here is relevant to two of aspects of compact objects: the shock in double detonation type Ia supernova and the signatures of a neutron star envelope. The work of Shen et al. suggests that thermonuclear eruptions in helium layers on white dwarf surfaces could lead to converging shocks that ignite C/O white dwarf stars. Additionally, the envelopes of neutron stars can reach keV temperatures and densities of a few hundred g cm-3. |
Monday, October 17, 2022 3:00PM - 3:12PM |
CO06.00006: CRASH Simulations of a Radiative Shock Experiment Using the ZEUS Laser Matthew Trantham, Julian Kinney, Carolyn C Kuranz The ZEUS laser at the University of Michigan was developed to investigate non-linear quantum electrodynamics in relativistic plasmas. It also has a long pulse laser, which can be used to drive shocks is a radiative environment and use the short pulse laser to create a betatron source for imaging. This study uses CRASH, a radiation-hydrodynamics code developed at the University of Michigan to model radiative shocks, to design and optimize an experimental platform for ZEUS. We show the initial result of our design study driving a shock in gasses of different densities and opacities to explore the dynamics of both radiative and non-radiative shocks. |
Monday, October 17, 2022 3:12PM - 3:24PM |
CO06.00007: Hydrodynamic instabilities and mixing in high energy density settings on NIF Bruce A Remington Hydrodynamic instability experiments are being developed and carried out on the National Ignition Facility (NIF) laser at LLNL through the NIF Discovery Science (basic science) program and the high energy density (HED) science program. The motivations are many, including supernova explosion dynamics; supernova remnant evolution; planetary formation dynamics; and asteroid impact and breakup dynamics; as well as basic research and development for HED and inertial confinement fusion (ICF) science. Examples include single-mode and multimode classical (non-stabilized) Rayleigh-Taylor (RT) experiments in planar geometry; classical RT in cylindrically convergent geometry; RT mixing into the hot spot at high compression in ICF capsule implosions; and ablation front RT experiments in direct drive; in indirect drive; and in nonlinear RT bubble merger regimes. Radiative shock stabilized RT instability experiments have also been developed; as well as material strength stabilized RT experiments at high pressures and strain rates in solid-state ductile metals. Examples will be given, connections to astrophysical and planetary science settings made, and future directions discussed. [1-13] |
Monday, October 17, 2022 3:24PM - 3:36PM |
CO06.00008: Photoionization Front Laboratory Experiments at the OMEGA Laser Facility Kwyntero V Kelso, Carolyn C Kuranz, Heath J LeFevre, Paul A Keiter, Sallee R Klein, William J Gray, Joshua S Davis, R P Drake Photoionization fronts are meaningful drivers of transformation for astrophysical phenomena. Generating sufficiently intense x-rays in laboratory experiments has been a difficult challenge. We attempt to create an environment relevant to astrophysical systems in which intense photon fluxes drive ionization and dynamics. Experiments at the OMEGA Laser Facility can create relevant photoionization conditions. One can generate a backlighter X-ray source through the ablation of an 860 micron diameter spherical nickel lined CH capsule. A laser irradiated gold foil generates an intense, thermal X-ray source (80-90 eV) which propagates into a gas cell filled with argon for the investigation of the Ka-absorption edge (3.203 keV). We present the preliminary results from an analytical study of the cold argon gas K-shell edge line absorption, characterized with a streak x-ray spectrometer using an RbAP crystal. We measured the K-edge of X-ray absorption spectra of argon gas using 2-4keV continuum photon energy from the capsule implosion. |
Monday, October 17, 2022 3:36PM - 3:48PM |
CO06.00009: High Repetition Rate Study of Biermann Battery Generated Magnetic Fields in Laser Produced Plasmas Jessica J Pilgram, Carmen G Constantin, Marissa B Adams, Robert S Dorst, Peter V Heuer, Marietta Kaloyan, Sofiya Ghazaryan, Derek B Schaeffer, Petros Tzeferacos, Christoph Niemann The Biermann Battery effect is a mechanism of spontaneous magnetic field generation in both astrophysical phenomena and laser produced plasmas (LPPs). This effect is caused by non-parallel temperature and density gradients within a plasma, represented in the magnetohydrodynamic framework by the baroclinic term in the induction equation, c/(ene)▽Te Χ ▽ne. In this talk we present a high repetition rate (~1 Hz) laboratory astrophysics experiment examining the spatial structure and evolution of Biermann generated magnetic fields in LPPs. Our measurements show azimuthally symmetric magnetic fields with peak values of 60 G in our closest measurements, 0.7 cm from the target surface. Optical Thomson scattering measurements give values for the electron temperature and density of the LPP on axis of Te = 10 ± 2 eV and ne = (5.55 ± 1) Χ 1016 cm-3 respectively. The effects of background gasses on Biermann generated fields are also discussed. |
Monday, October 17, 2022 3:48PM - 4:00PM |
CO06.00010: Measurements of Anisotropic Electron Temperatures in Magnetized Gas-Jet Plasmas Zachariah E Barfield, Jonathan L Peebles, Joseph D Katz, Peter V Heuer, Dustin Froula Experiments at the Omega Laser Facility have utilized a magnetized gas-jet platform to infer anisotropic electron temperatures in a low-density nitrogen plasma (ne ~ 5 × 1018 cm–3). With a 15-T field, the magnetic-field pressure is comparable to the plasma electron pressure (β ≈ 2). Thomson-scattering analysis show the spectral density function changes relative to the axis of the magnetic field. This temperature anisotropy persists on a nanosecond time scale, well exceeding collision time scales at these conditions. These results suggest an adiabatic cooling mechanism is driving the anisotropy. |
Monday, October 17, 2022 4:00PM - 4:12PM |
CO06.00011: Experiments and simulations investigating filamentary instabilities in ns-duration-laser-driven expanding plasmas Graeme D Sutcliffe, Patrick J Adrian, Jacob A Pearcy, Tim M Johnson, Justin H Kunimune, Bradley B Pollock, John D Moody, Chikang Li Theoretically predicted to exist in plasmas with an anisotropic electron distribution function and later confirmed in computational studies, the electron Weibel instability is observed experimentally in an expanding high-energy-density (HED) plasma generated with a modest intensity ~2e14 W/cm2, ~1 ns laser. The observed structures have wavelengths ~150-220 μm and growth rates 0.4-1.0 1/ns, consistent with an electron-driven Weibel instability where the anisotropy in the electron distribution is small, A~0.002. This mechanism is found to be a better match to observations than other field generation mechanisms typically found in HED plasmas, including counter-streaming ion Weibel and magnetothermal instabilities. These observations show experimentally that the electron Weibel instability must be considered alongside other magnetic field generation and amplification mechanisms in expanding ablation plasmas ubiquitous in HED research, and possibly large-scale astrophysical plasmas. Additionally, inspection of the scaling of the magnetic power spectrum shows a possible scaling match to analytic gyrokinetic predictions of turbulence: B ∝ k-16/3, which motivates future investigation. Simulations of future experimental conditions are presented to guide design considerations. |
Monday, October 17, 2022 4:12PM - 4:24PM Not Participating |
CO06.00012: Behavior of the Thermal Cooling Instability at High-Energy-Density Scales Rachel Young, Matthew Trantham, Patrick Hartigan, Carolyn C Kuranz The thermal cooling instability has been the subject of one and two-dimensional numerical studies at astrophysical scales, but numerical simulations that directly capture its behavior at high-energy-density scales (L ∽ 1 mm, τ ∽ 1 ns) have been scarce. We have recently completed a series of studies of the thermal cooling instability using CRASH, the University of Michigan's predictive radiative hydrodynamic code. We will present the results of study of the thermal cooling instability using artificial cooling functions of the form Λ ∝ Teα and varied α (Λ has units energy per volume per time). This was intended to test an analytic prediction: systems are expected to transition from unstable to stable at α > αcrit, where αcrit = 2. At incoming velocities above 300 km/s, we found αcrit ≈ 2.3. However, as the incoming velocity dropped, αcrit shifted to higher values, suggesting that the thermal cooling instability may be occurring in regimes where it was previously thought impossible. |
Monday, October 17, 2022 4:24PM - 4:36PM |
CO06.00013: Laboratory study of the initial stages of quasi-parallel collisionless shocks relevant to supernova remnants (SNR) Simon Bolaños, Mario Manuel, Marissa B Adams, Mathieu Bailly-Grandvaux, Alemayehu Bogale, David Michta, Petros Tzeferacos, Farhat N Beg Collisionless shocks are ubiquitous in astrophysics and a possible source of the highest-energy cosmic rays in our universe. Over the last decade, experimental and numerical efforts have shown that ion-Weibel instability is a leading candidate mechanism for collisionless shock formation in unmagnetized astrophysical objects. In a magnetized environment, ion streaming instabilities, such as the non-resonant instability (NRI), can dominate the dynamics and mediate the development of collisionless shocks. This mediation occurs in a quasi-parallel configuration, meaning that the plasma flow is parallel to the ambient magnetic field. |
Monday, October 17, 2022 4:36PM - 4:48PM |
CO06.00014: Using Optical Thomson Scattering to Determine Transport Properties in a Turbulent Plasma Hannah Poole, Charlotte A Palmer, Archie F Bott, Petros Tzeferacos, Dustin Froula, Joseph D Katz, James S Ross, Hye-Sook Park, Yingchao Lu, Adam Reyes, George F Swadling, Sam Iaquinta, Jena Meinecke, Alexander A Schekochihin, Don Q Lamb, Sean P Regan, Gianluca Gregori Dynamo in astrophysical turbulence is a key process for the amplification of magnetic fields. The advent of high-power laser systems, such as the Laboratory for Laser Energetics' OMEGA and Lawrence Livermore National Laboratory's National Ignition Facility (NIF), has made it possible to recreate these astrophysical conditions in terrestrial laboratories. Presented here are data obtained from an experimental campaign conducted on OMEGA that aimed to demonstrate dynamo amplification. This work focuses on the optical Thomson scattering data collected to investigate the transport properties of the turbulent plasma. By time-resolving the ion-acoustic wave and electron plasma wave scattering, their autocorrelation can be used to extract relevant transport properties, such as diffusion and thermal conductivity. We intend to extend this analysis to the NIF where significant modification of heat transport is expected to occur. |
Monday, October 17, 2022 4:48PM - 5:00PM |
CO06.00015: A platform to investigate collisionless pair beam-plasma instabilities at CERN Charles D Arrowsmith, Pascal Simon, Nikolaos Charitonidis, Raspberry A Simpson, Daniel J Haberberger, Pablo J Bilbao, Tom Hodge, Jon T Gudmundsson, Jessica L Shaw, Dustin Froula, Hui Chen, Luis O Silva, Brian Reville, Subir Sarkar, Raoul M Trines, Brian T Huffman, Robert Bingham, Gianluca Gregori We report updates on a new experimental platform being developed at the HiRadMat facility at CERN. Beams of 440 GeV protons will be used to produce electron-positron pair beams, and a plasma cell used to study collisionless kinetic electron-positron beam-plasma instabilities. The experiment aims to reproduce in the laboratory, processes relevant to the propagation and stability of relativistic pair plasmas associated with extreme relativistic phenomena such as Gamma-ray Bursts. In fact, Weibel and oblique streaming instabilities are believed to drive the generation of magnetic fields, which are only indirectly inferred by the observed synchrotron emission. Here we present the results of an inductive radio-frequency plasma discharge which has been constructed to simulate the propagation of the pair beam through the interstellar medium. Measurements using a Langmuir probe have confirmed that the plasma cell parameters are well-suited to a laboratory study of beam-plasma instabilities of relativistic electron-positron beams. HiRadMat is ideally placed to provide a new platform for laboratory astrophysics. |
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