Bulletin of the American Physical Society
62nd Annual Meeting of the APS Division of Plasma Physics
Volume 65, Number 11
Monday–Friday, November 9–13, 2020; Remote; Time Zone: Central Standard Time, USA
Session JO06: HED: Laboratory Astrophysics IILive
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Chair: Derek Schaeffer, Princeton |
Tuesday, November 10, 2020 2:00PM - 2:12PM Live |
JO06.00001: Nuclear astrophysics experiments at high-energy-density conditions Alex Zylstra, Dan Casey, Chris Weber, Justin Jeet, Jeff Burggraf, Charlie Cerjan, Dieter Schneider, Maria Gatu Johnson, Johan Frenje, Neel Kabadi, Hans Herrmann, Yongho Kim High-energy-density plasmas are an excellent surrogate for astrophysical conditions under which nucleosynthesis occurs. Recent examples of astrophysically-relevant experiments include measurements of the p+D fusion cross section relevant to big-bang nucleosynthesis [A.B. Zylstra et al., Phys. Rev. C 101, 042802(R) (2020)]. Future experiments are being developed to pursue measurements of specific processes occurring in plasmas, including modifications of the cross section due to electron screening effects, which are important for stellar nucleosynthesis models. Work on developing an implosion platform on NIF for electron screening measurements will be presented, in addition to an overview of other nuclear astrophysics work on cross-section measurements and reactions on excited states in the plasma. [Preview Abstract] |
Tuesday, November 10, 2020 2:12PM - 2:24PM Live |
JO06.00002: Recent measurements of iron opacity on the National Ignition Facility (NIF) T.S. Perry, H.M. Johns, E.S. Dodd, N.S. Vinyard, C.J. Fontes, J.P. Colgan, K.A. Flippo, T. Cardenas, T.H. Day, L. Kot, T.J. Urbatsch, M.R. Douglas, M.E. Sherrill, R.F. Heeter, Y.P. Opachich, R.A. London, B.G. Wilson, C.A. Iglesias, M.B. Schneider, J.M. Heinmiller, M.S. Wallace, E.C. Dutra, J.E. Bailey Radiation transport in high energy density experiments is highly dependent on the x-ray opacity of the material. An experimental platform on the National Ignition Facility has been developed to measure the opacity of materials at densities and temperatures that are comparable to those found in the interior of the sun. The platform consists of a hohlraum to heat the material, a source of x-rays to backlight the sample, and a spectrometer to measure the spectrally resolved transmission of the sample. Experiments in the past year have focused on making measurements at different temperatures and densities. The results of these experiments on iron will be presented and compared to past results and to theoretical calculations. [Preview Abstract] |
Tuesday, November 10, 2020 2:24PM - 2:36PM Live |
JO06.00003: DANTE as a Primary Temperature Diagnostic for the NIF Iron Opacity Campaign. Y.P. Opachich, R.F. Heeter, C.D. Harris, H. M. Johns, E. S. Dodd, J. L. Kline, N. S. Krasheninnikova, M. J. May, A. S. Moore, M. S. Rubery, M. B. Schneider, T. J. Urbatsch, K. Widmann, T. S. Perry The Opacity Platform on the National Ignition Facility (NIF) has been developed to measure iron opacities at varying densities and temperatures relevant to the solar interior, and to verify recent experimental results obtained at the Sandia Z-machine, which diverge from theory. The first set of NIF experiments collected iron opacity data at \textasciitilde 150-160 eV, and an electron density of \textasciitilde 7x10$^{\mathrm{21}}$ cm$^{\mathrm{-3}}$, with a goal to study temperatures up to \textasciitilde 210 eV, with electron densities of up to \textasciitilde 3x10$^{\mathrm{22}}$ cm$^{\mathrm{-3}}$. Among several techniques used to infer the temperature of the heated Fe sample, the absolutely calibrated DANTE-2 filtered diode array provides measurements of the hohlraum temperature near the sample. However, the DANTE-2 temperatures are consistently low compared to pre-shot LASNEX simulations for a range of laser drive energies. It has previously been shown that an uncertainty of \textpm 5{\%} or better, can be achieved with appropriate spectral coverage and channel participation. We present the results and future plans of an effort to reevaluate the estimated uncertainty in the reported DANTE-2 temperature measurements. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. [Preview Abstract] |
Tuesday, November 10, 2020 2:36PM - 2:48PM Live |
JO06.00004: Characterization of KAP and RbAP Crystals Using Soft X-Rays for NIF Opacity Spectrometer Alice Durand, R. Lara, EC Dutra, MS Wallace, RA Knight, JM Heinmiller, RF Heeter, J Emig, T Archuletta, TS Perry, K Flippo, TJ Urbatsch Accurate characterization of the Opacity Spectrometer (OpSpec) crystals is paramount in ensuring high-quality data from soft X-ray opacity experiments performed at the National Ignition Facility (NIF). Such data addresses the discrepancy between opacity theory and experiments. The Henke X-ray diffractometer at the Nevada National Security Site is being used for high-fidelity crystal characterization. The procedure provides detailed crystal spectra, accommodating a range of different tests, for advances in crystal and spectrometer design. Potassium acid phthalate (KAP) and rubidium acid phthalate (RbAP) crystals are typically characterized at operating voltage and current of 2.5 kV, 15 mA or 15 kV, 20 mA. Image plates are used to record the spectra and are used for identification of crystal defects both before and after NIF shots. Further characterization improvements are underway regarding crystal shape, anode choice, and analysis procedure. [Preview Abstract] |
Tuesday, November 10, 2020 2:48PM - 3:00PM Live |
JO06.00005: Calibration of AGFA D4 and D3sc X-Ray Films in the 0.7 to 4.6 keV Energy Range for NIF Opacity Spectrometer. Eric Dutra, Alice Durand, Russell Knight, Raul Lara, Gabriel Torres, Matthew Wallace, Jim Emig, Robert Heeter, Joe Cowan, Ted Perry, James Knauer X-ray films still remain a key asset for high-resolution X-ray spectral imaging in High-Energy Density (HED) experiments conducted at the National Ignition Facility (NIF). The soft X-ray Opacity Spectrometer (OpSpec) fielded at the NIF has an elliptically shaped crystal design that measures X-rays in the 900-2100 eV range and currently uses image plates as the detecting medium. However, the higher spatial resolution of AGFA D4 and D3sc X-ray films provides increased spectral resolution to the data over the current IP-TR image plates, which drives the new iteration of OpSpec to include X-ray film as a detecting medium. The calibration of AGFA D4 and D3sc X-ray films used in new iterations of the OpSpec is communicated here. These calibration efforts are vital to the NIF opacity measurements and are conducted in a previously un-studied X-ray energy range under a new film development protocol required by NIF. The absolute response of AGFA D4 and D3sc X-ray films from 705 to 4620 eV is being measured using the Nevada National Security Site Manson X-ray source with select anodes and filters to produce well-defined X-ray line energies. [Preview Abstract] |
Tuesday, November 10, 2020 3:00PM - 3:12PM Live |
JO06.00006: An Extended X-Ray Absorption Fine Structure Spectroscopy Study of Iron and Iron Oxide David Chin, Phil Nilson, JJ Ruby, Danae Polsin, Xuchen Gong, Mary Kate Ginnane, J. Ryan Rygg, Gilbert Collins, Dustin Trail, Yuan Ping, Federica Coppari, Alexis Amouretti, Marion Harmand To increase our understanding of the formation and evolution of the Earth and iron-rich exoplanets, extended x-ray absorption fine structure (EXAFS) spectroscopy was used to characterize iron and iron oxides dynamically compressed to core Earth and super-Earth conditions. At the Omega Laser Facility, iron and iron oxides were ramp compressed to above 500 GPa and probed with a broadband x-ray source. The spatial and spectral behavior of the x-ray source was characterized using time integrating and time-resolved diagnostics. A new x-ray spectrometer was developed to improve the spectral resolution of the EXAFS measurement. By using a silicon mirror and new target geometry, EXAFS and VISAR (velocity interferometer system for any reflector) measurements were successfully carried out on the same shot, allowing for a complete and simultaneous equation-of-state measurement of pressure, density, and temperature. The temperature in the sample was determined from the EXAFS data by characterizing the ion positions in the crystal lattice. [Preview Abstract] |
Tuesday, November 10, 2020 3:12PM - 3:24PM Live |
JO06.00007: Simulations of Marshak Wave Through Iron Oxide Foam Kyle McLean, Steve Rose Past experiments carried out in Sandia National Laboratory have shown severe discrepancies between opacity models and experimentally measured opacity, particularly in Iron under conditions similar to those found in the solar tachocline. To provide further investigation into existing models, an experiment was performed on the National Ignition Facility whereby a Marshak wave, formed from the interaction of an X-ray blackbody drive with an iron oxide (Fe$_{\mathrm{2}}$O$_{\mathrm{3}})$ foam, was allowed to propagate through the material until emerging as a measurable flux from the far end of the foam. By measuring this flux, one can deduce information about the inner opacity profile of Iron. In this talk, I will discuss the work carried out using a bespoke multigroup diffusion solver designed to simulate this experiment, probing specific sensitivity to properties such as equation of state and underlying opacity models. [Preview Abstract] |
Tuesday, November 10, 2020 3:24PM - 3:36PM Live |
JO06.00008: Radiative shock properties using x-ray Thomson scattering and self-emission measurements on the National Ignition Facility Heath LeFevre, Kevin Ma, Michael MacDonald, Tilo Doeppner, Marius Millot, Channing Huntington, Paul Keiter, Eric Johnsen, Carolyn Kuranz Radiative shocks are relevant to a variety of astrophysical phenomena, such as supernova remnants and accretion shocks. Experiments to understand the structure and radiation transport in radiative shocks inform the interpretation of observational data and improve simulation codes. A recent Discovery Science campaign measured radiative shocks using x-ray Thomson scattering and streaked self-emission from the heated material to extract quantitative information about the temperature profile and radiation transport. The experiment uses a halfraum to drive a radiative shock into a 20 mg cm$^{-3}$ CH foam and a Zn probe foil to produce 9 keV emission for the scattering measurement. The self-emission diagnostic determined the average shock velocity is 130 $\mu$m ns$^{-1}$. This presentation will present the analysis of the scattering and self-emission data collected during the recent discovery science campaign. [Preview Abstract] |
Tuesday, November 10, 2020 3:36PM - 3:48PM Live |
JO06.00009: A Photoionized Plasma Experiment Driven by a Long Duration X-Ray Flux at OMEGA EP Roberto Mancini, D Mayes, R Schoenfeld, J Rowland, R Heeter, D Liedahl, S Regan Achieving photoionization equilibrium in the laboratory is a standing challenge of photoionized plasma experiments and key for testing physics models employed in the interpretation of x-ray astronomy observations. An experimental platform has been developed at the OMEGA EP laser in which a tamped silicon sample is driven by a three-Cu hohlraum source that produces a 30ns-duration, broadband x-ray flux with a radiation temperature of 90eV. The long duration x-ray flux is critical for producing a photoionized plasma in steady-state in the laboratory. The x-ray source performance is monitored with VISAR and its spectral distribution is characterized with a grating spectrometer. The silicon plasma is diagnosed with L-shell self-emission and K-shell absorption spectroscopy. The latter is afforded by using a laser beam to drive a separate short-duration source of backlighting photons. Probing the silicon plasma at different times provides an experimental check of the steady-state condition in the photoionized plasma. We will discuss modeling simulations done to design the experiment and the observations recorded during the first series of shots at OMEGA EP. This work is supported by DOE NNSA NLUF Grant DE-NA0003936. [Preview Abstract] |
Tuesday, November 10, 2020 3:48PM - 4:00PM Live |
JO06.00010: A Laboratory Astrophysical Jet Validation Test of the Radiation Hydrodynamics Capabilities of the FLASH Code Chris Orban, Milad Fatenejad, Don Q. Lamb The potential for laser-produced plasmas to yield fundamental insights into HEDP can be frustrated by uncertainties in modeling these plasmas using radiation-hydrodynamics codes. In an effort to overcome this and to corroborate the accuracy of the HEDP capabilities that have been added to the publicly available FLASH radiation-hydrodynamics code, we present detailed code-to-code comparisons between FLASH and the HYDRA code developed at Lawrence Livermore National Laboratory using previously published HYDRA simulations from Grava et al. 2008. That study describes a laser experiment that produced a jet-like feature that the authors compare to astrophysical jets. Importantly, the Grava et al. 2008 experiment included interferometric measurements of electron number densities. Despite radically different methods for treating the computational mesh, and different equation of state and opacity models, the FLASH results greatly resemble the results from HYDRA and, most importantly, the experimental measurements of electron density. Having validated the FLASH code in this way, we use the code to further investigate and understand the formation of the jet seen in the Grava et al. (2008) experiment and discuss its relation to the Wan et al. (1997) experiment at the NOVA laser. [Preview Abstract] |
Tuesday, November 10, 2020 4:00PM - 4:12PM Live |
JO06.00011: A Simple Monte-Carlo Model of the Late-Time Evolution of Laser-Produced Plasmas for Laboratory Astrophysics Peter Heuer, Robert Dorst, Martin Weidl, Derek Schaeffer, Carmen Constantin, Christoph Niemann Laboratory astrophysics experiments that employ large scale (>10 cm) laser-produced plasmas (LPPs) often depend strongly on the LPP density, but the computational cost of modeling the time evolution of the LPP density presents challenges when designing experiments. Large ion gyroradii relative to experimental scales preclude fluid approximations, while large experimental volumes make particle-in-cell (PIC) and 3D hybrid models computationally expensive. In some cases, this problem can be made tractable by using a simple model in which ion interactions are collectively modelled as a single cross-field diffusion process such that ions follow cyclotron orbit trajectories with diffusing gyrocenters. Under this approximation, a Monte-Carlo approach can be applied to numerically estimate the evolution of the LPP density. The computational diffusion coefficient can be adjusted to match experimental results, improving the accuracy of the model and giving physical insight into the experimentally-relevant diffusion processes. In this presentation we discuss this model in depth, present an example application of this technique to model the expansion of a LPP over ten meters through a background plasma, and show how the model can be used to inform the design of future experiments. [Preview Abstract] |
Tuesday, November 10, 2020 4:12PM - 4:24PM Live |
JO06.00012: Exploring the universe through Discovery Science on the National Ignition Facility (NIF) Bruce Remington Highlights from the NIF Discovery Science program will be presented. Examples include nuclear reactions relevant to stellar nucleosynthesis [1]; equations of state at high pressures relevant to planetary interiors [2, 3, 4] and white dwarf envelopes [5]; Rayleigh-Taylor instabilities relevant to supernovae and supernova remnant evolution [6, 7, 8]; relativistically hot plasmas [9] and target normal sheath acceleration of protons on NIF ARC [10]; magnetic reconnection at high energy densities [11]; and high velocity interpenetrating plasmas that generate collisionless astrophysical shocks, magnetic fields, and accelerate particles relevant to cosmic ray generation [12, 13]. [1] M. Gatu Johnson, PoP 24, 041407 (2017) [2] P.M. Celliers, Science 361, 677 (2018) [3] R.F. Smith, Nat. Astron. 2, 452 (2018) [4] T. Döppner, PRL 121, 025001 (2018) [5] A.L. Kritcher, Nature, in press (2020) [6] C.C. Kuranz, Nat. Com. 9, 1564 (2018) [7] J.P. Sauppe, PRL 124, 185003 (2020) [8] S. Palaniyappan, PoP 27, 047208 (2020) [9] G.J. Williams, PRE 101, 031201 (2020) [10] D. Mariscal, PoP 26, 043110 (2019) [11] W. Fox, PRL, submitted (2020) [12] F. Fiuza, Nat. Phys. in press (2020) [13] D.P. Higginson, PoP 26, 012113 (2019) [Preview Abstract] |
Tuesday, November 10, 2020 4:24PM - 4:36PM Live |
JO06.00013: Modeling the Thermal Cooling Instability with CRASH Rachel Young, Matthew Trantham, Carolyn Kuranz We will present the results of one and two-dimensional simulations of the thermal cooling instability using CRASH, the University of Michigan’s radiation hydrodynamics code. The thermal cooling instability has long been a subject of interest in astrophysics, where it is credited with altering a wide variety of phenomena, ranging from accretion shocks on white dwarf stars (length scale $10^8$ cm) to colliding stellar wind bubbles (length scale $10^{20}$ cm). Astrophysicists have done a great deal of work understanding their own parameter space and how incoming velocity and density affect the instability. Our work extends their approach to the high-energy-density parameter space. As time allows, we will discuss the implications for building high-energy-density experiments. This work is funded by the U.S. Department of Energy NNSA Center of Excellence under cooperative agreement number DE-NA0003869 and the National Science Foundation through the Basic Plasma Science and Engineering program NSF 16-564, grant number 1707260. [Preview Abstract] |
Tuesday, November 10, 2020 4:36PM - 4:48PM On Demand |
JO06.00014: Sound Velocity in Shocked Iron to \textasciitilde 2700 GPa Margaret Huff, Linda Crandall, J.R. Rygg, Brian Henderson, Mohamed Zaghoo, G.W. Collins, Chad McCoy, Dayne Fratanduono, Peter Celliers, Jon Eggert Measurements of the sound speed in a shock-compressed material have long been sought because they provide important information about the thermodynamic derivative in the equation of state of that material at high pressure. Specifically, constraining the sound speed in iron at high pressures can be useful to planetary science and geophysics to understand core formation and dynamo physics. We present measurements of shock{\-}compressed iron sound speed to pressures of $\sim $400 to 2700 GPa. A novel nonsteady wave-analysis technique\footnote{ D. E. Fratanduono \textit{et al.}, J. Appl. Phys. \textbf{116}, 033517 (2014).} allows us to infer sound speed from the relative arrival times of pressure perturbations that transited the shocked sample material and an adjacent reference material.~This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944. [Preview Abstract] |
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