Bulletin of the American Physical Society
55th Annual Meeting of the APS Division of Plasma Physics
Volume 58, Number 16
Monday–Friday, November 11–15, 2013; Denver, Colorado
Session CO6: WDM, EOS, RAD Shocks |
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Chair: Dustin Froula, University of Rochester Room: Governor's Square 11 |
Monday, November 11, 2013 2:00PM - 2:12PM |
CO6.00001: Molecular systems under shock compression into the dense plasma regime: carbon dioxide and hydrocarbon polymers Thomas R. Mattsson, Kyle R. Cochrane, Seth Root, John H. Carpenter Density Functional Theory (DFT) has proven remarkably accurate in predicting properties of matter under shock compression into the dense plasma regime. Materials where chemistry plays a role are of interest for many applications, including planetary science and inertial confinement fusion (ICF). As examples of systems where chemical reactions are important, and demonstration of the high fidelity possible for these both structurally and chemically complex systems, we will discuss shock- and re-shock of liquid carbon dioxide (CO2) in the range 100 to 800 GPa [1] and shock compression of hydrocarbon polymers, including GDP (glow discharge polymer) which is used as an ablator in laser ICF experiments. Experimental results from Sandia's Z machine validate the DFT simulations at extreme conditions and the combination of experiment and DFT provide reliable data for evaluating existing and constructing future wide-range equations of state models for molecular compounds. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.\\[4pt] [1] S. Root et. al Phys. Rev. B {\bf 87}, 224102 (2013) [Preview Abstract] |
Monday, November 11, 2013 2:12PM - 2:24PM |
CO6.00002: Proton Stopping Power in Warm Dense Hydrogen Drew Higginson, Sophia Chen, Stefano Atzeni, Maxence Gauthier, Feliciana Mangia, Jean-Rapha\"el Marqu\`es, Rapha\"el Riquier, Julien Fuchs Warm dense matter (WDM) research is fundamental to many fields of physics including fusion sciences, and astrophysical phenomena. In the WDM regime, particle stopping-power differs significantly from cold matter and ideal plasma due to free electron contributions, plasma correlation effects and electron degeneracy. The creation of WDM with temporal duration consistent with the particles probes is difficult to achieve experimentally. The short-pulse laser platform allows for the production of WDM along with relatively short bunches of protons compatible of such measurements, however, until recently, the intrinsic broadband proton spectrum was not well suited to investigate the stopping power directly. This difficulty has been overcome using a novel magnetic particle selector ($\Delta $E/E$=$ 10{\%}) to select protons (in the range 100-1000 keV) as demonstrated with the ELFIE laser in LULI, France. These protons bunches probe high-density (5 $\times$ 10$^{20}$ cm$^{-3})$ gases (H, He) heated by a nanosecond laser to reach estimated temperatures above 100 eV. Measurement of the proton energy loss within the heated gas allows the stopping power to be determined quantitatively. The experimental results in cold matter are compared to preexisting models to give credibility to the measurement technique. The results from heated matter show that the stopping power of 450 keV protons is dramatically reduced within heated hydrogen plasma. [Preview Abstract] |
Monday, November 11, 2013 2:24PM - 2:36PM |
CO6.00003: X-ray Thomson Scattering Development for Z E.C. Harding, T. Ao, J.E. Bailey, S.B. Hansen, R.W. Lemke, D.B. Sinars, G.A. Rochau, M.P. Desjarlais, L.P. Mix, I.C. Smith, J. Reneker, G. Gregori X-ray Thomson Scattering experiments were recently conducted on Sandia's Z machine using a newly developed experimental platform. This platform exploits Z's unique capability to generate large volumes of uniformly shocked warm dense matter. The scattering target is CH$_{2}$ foam (0.1 g/cc), and is designed to reach a temperature (pressure) of 2.4 eV (0.3 Mbar). X-rays generated from a laser heated Mn foil probe the foam in the non-collective regime. An imaging spectrometer collects the scattered x-rays with a spherically-bent Germanium crystal that provides spatial resolution across the shocked and unshocked foam. We present the results and analysis from several fully integrated Z experiments. The resulting spectra are compared to various bound-free scattering models. [Preview Abstract] |
Monday, November 11, 2013 2:36PM - 2:48PM |
CO6.00004: Thermal conductivity measurements of CH and Be by refraction-enhanced x-ray radiography Yuan Ping, Jim King, Otto Landen, Jeff Koch, Russell Wallace, Rick Freeman, Tom Boehly, Glibert Collins A novel technique, time-resolved refraction-enhanced x-ray radiography, is developed to study thermal conductivity at an interface. Experiments using OMEGA laser have been carried out for CH/Be targets isochorically heated by x-rays to measure the evolution of the density gradient at the interface due to thermal conduction. The sensitivity of this radiographic technique to discontinuities enabled observation of shock/rarefraction waves propagating away from the interface. The radiographs provide enough constraints on the temperatures, densities and scale lengths in CH and Be, respectively. Preliminary data analysis suggests that the thermal conductivities of CH and Be at near solid density and a few eV temperature are higher than predictions by the commonly used Lee-More model. Detailed analysis and comparison with various models will be presented. [Preview Abstract] |
Monday, November 11, 2013 2:48PM - 3:00PM |
CO6.00005: Thermoelectric transport properties of warm dense molybdenum from first-principles simulations Martin French, Thomas Haill, Michael Desjarlais, Thomas Mattsson Molybdenum, with its high melting point, significant electrical conductivity, and high material strength, is a technologically important material in general and has in particular recently been proposed as a driver material in high-pressure strength experiments on Sandia's Z-machine [1]. To simulate and understand the processes in these experiments with magneto-hydrodynamic simulations, accurate models for the electrical and thermal conductivity are needed for a wide range of thermodynamic parameters. Here, we present novel results for the electrical and thermal conductivity of molybdenum in various states ranging from the solid to the dense plasma phase. The results were obtained with first-principles simulation techniques that combine density functional theory with molecular dynamics and linear response theory. We find good agreement between our theoretical results and available experimental data. Sandia National Laboratories is a multiprogram laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under Contract No. DE-AC04-94AL85000.\\[4pt] [1] C. S. Alexander, J. R. Asay, T. A. Haill, J. Appl. Phys. 108, 126101 (2010) [Preview Abstract] |
Monday, November 11, 2013 3:00PM - 3:12PM |
CO6.00006: A Strongly-Coupled Average Atom Model for Warm Dense Mixtures Liam Stanton, Michael Murillo We present a new average atom model to determine the properties of dense, multi-component plasmas. Strong ion correlations are taken into account through the quantum Ornstein-Zernike relations and hypernetted-chain closures, while an orbital-free density functional theory is employed to calculate electronic structure. The formalism is derived without reference to a mean ionization state of the system which allows for a more consistent generalization to mixtures. Applications to EOS and XRTS are discussed, and numerical simulations are compared with other methods and experimental data. [Preview Abstract] |
Monday, November 11, 2013 3:12PM - 3:24PM |
CO6.00007: Spectrally and angularly resolved x-ray scattering measurements of shock-compressed aluminum Luke Fletcher Measurements of the strength in the ionic structure factor at various scattering angles is important for accurate first-principle calculations of material properties in the high pressure and temperature phase. In this study, spectrally resolved XRTS measurements in combination with proof-of-principle, single shot 2D angularly resolved x-ray scattering measurements of changes in the ion-ion correlation peak for both single and double (counter-propagating) shocks have been observed in Al foils. A binary 527 nm, 2 GW laser system available at the MEC station of the LCLS facility has been used to compress 25 $\mu $m and 50 $\mu $m thick Al targets approximately 2x and 3x the solid density respectively. A drive intensity of 6x10$^{14}$ W/cm$^{2}$ on each irradiated surface was used to generate high pressure shock waves into the sample while 8 keV x-rays from the LCLS were used to probe the compressed targets for both single and double shocked geometries. The results will show that the elastic x-ray scattering amplitude, angularly resolved, shifts to higher wave numbers with increasing density, while the width and peak amplitude provide information on the temperature and ionization state. [Preview Abstract] |
Monday, November 11, 2013 3:24PM - 3:36PM |
CO6.00008: Quantifying uncertainty in high-energy-density radiative shock experiments Carolyn Kuranz, R.P. Drake, M.J. Grosskopf, M.R. Trantham, J.P. Holloway, D. Bingham, J. Goh Radiative shocks, which are in a regime where most of the incoming energy flux is converted into radiation, occur in astrophysical systems as well as inertial confinement fusion experiments. We have performed radiative shock experiments on the Omega laser facility that irradiate a thin Be disk with a laser irradiance of $\sim$ 10$^{15}$ W/cm$^{2}$. The ablation pressure creates a 40 Mbar shock in the Be, which breaks out into Xe gas at 1.1 atm. The shock can reach velocities of over 130 km/s. At such high velocities the radiative fluxes become significant, which leads to extensive radiative cooling. Experimental results to be presented include observations ranging from about 0.5 ns until 26 ns after the laser pulse is initiated. Experiments were performed over multiple shot days and this presentation will address the variation and uncertainty in these experiments. Data will be compared to results from the 3D radiation-hydrodynamic code developed at our Center for Radiative Shock Hydrodynamics. This work is funded by the PSAAP in NNSA-ASC via grant DEFC52- 08NA28616, by the NNSA-DS and SC-OFES Joint Program in HEDLP, grant number DE-FG52-09NA29548, and by the NLUF Program, grant number~DE-NA0000850. [Preview Abstract] |
Monday, November 11, 2013 3:36PM - 3:48PM |
CO6.00009: Exotic hollow atom states pumped by relativistic laser plasma in a radiation dominant regime Nigel Woolsey, S.A. Pikuz, A. Ya Faenov, R.J. Dance, E. Wagenaars, N. Booth, O. Culfa, R.G. Evans, R.J. Gray, T. Kaempfer, K.L. Lancaster, P. McKenna, A.L. Rossall, I. Yu Skobelev, K.S. Schulze, I. Uschmann, A.G. Zhidkov, J. Abdallah Jr., J. Colgan In high-spectral resolution experiments with the petawatt Vulcan laser, strong x-ray radiation of KK hollow atoms (atoms without n $=$ 1 electrons) from aluminium targets was observed at high laser contrast, for intensities of 3x10$^{20}$ Wcm$^{-2}$ and micron thick targets. These spectral observations are interpreted using detailed atomic kinetics calculations suggesting these exotic hollow atom states occur at near solid density and are driven by an intense polychromatic x-ray field. We estimate that this x-ray radiation field has energy in the kilovolt range and has an intensity exceeding 10$^{18}$ Wcm$^{-2}$. The field may arise through relativistic electron Thomson scattering and bremsstrahlung in the electrostatic fields at the target surface. [Preview Abstract] |
Monday, November 11, 2013 3:48PM - 4:00PM |
CO6.00010: Improvements and modeling calculations for a laboratory photoionized plasma experiment at Z relevant to astrophysics T.E. Lockard, D.C. Mayes, T. Durmaz, R.C. Mancini, G. Loisel, J.E. Bailey, G.A. Rochau, D.A. Liedahl, R.F. Heeter Creating a photoionized plasma in a controlled laboratory environment is difficult due to the intense x-ray flux needed to drive the plasma. This is overcome by the intense flux of x-ray photons produced by the pulsed power Z-machine at Sandia National Laboratories. We discuss improvements to a gascell experiment at Z including new ultrathin windows and window plates, and lower filling pressures that permit producing photoionized plasmas of larger ionization parameters. To understand the radiation environment, constrained view-factor calculations have been performed to model the x-ray flux at the gascell. Radiation-hydrodynamic simulations were also done to provide information on the overall evolution of the plasma and, in particular, the radiation heating of the plasma including non-equilibrium effects. We will also discuss a series of collisional-radiative atomic kinetics calculations that were done using a collection of laboratory and astrophysics codes. These results are useful to understand the relative importance of photon- and particle-driven atomic processes in the plasma. [Preview Abstract] |
Monday, November 11, 2013 4:00PM - 4:12PM |
CO6.00011: Laboratory photoionized plasma experiments at Z - Comparison with modeling D. Mayes, T. Lockard, T. Durmaz, I. Hall, R. Mancini, J. Bailey, G. Rochau, G. Loisel, R. Heeter, D. Liedahl Photoionized plasmas are common in astrophysical environments, such as x-ray binaries and active galactic nuclei. We discuss an experimental and modeling effort to study the atomic kinetics in plasmas of this type via K-shell line absorption spectroscopy. Results from a first pass thru our 2nd-generation dataset are compared with results of several modeling codes attempting to simulate our experimental conditions. The experiment employs the intense x-ray flux emitted by the collapse of a z-pinch to produce and backlight a Neon photoionized plasma in a cm-scale gas cell at various distances from the z-pinch. The filling pressure is monitored in situ providing the plasma particle number density. High-resolution spectra from a TREX spectrometer are processed with a suite of specially designed IDL tools to produce transmission spectra, which show absorption in several ionization stages of Neon. Analysis independent of atomic kinetics calculations yields the charge state distribution and ion areal densities used to benchmark atomic kinetics codes. In addition, the electron temperature, extracted from a level population ratio, is used to test heating models. [Preview Abstract] |
Monday, November 11, 2013 4:12PM - 4:24PM |
CO6.00012: Equation of state measurements of CH plastic at Gbar pressures using the National Ignition Facility Tilo Doeppner, A. Kritcher, D. Swift, J. Hawreliak, G. Collins, C. Keane, O. Landen, T. Ma, S. Le Pape, H.J. Lee, S. Glenzer, P. Neumayer, D. Chapman, S. Rothman, R. Falcone We have used the National Ignition Facility (NIF) to conduct absolute equation of state and opacity measurements of plastic CH along the principal Hugoniot at unprecedented pressures, approaching 1 Gbar. A 5 ns long, 1.3 MJ laser pulse at 351 nm, generating a hohlraum drive with 290 eV peak radiation temperature, launches a strong shock wave into a 2.2 mm diameter plastic ball. The induced pressures by the spherical shock wave increase as the shock converges, accessing a range of Hugoniot states in a single experiment. We measure compression from the radiography contrast at the shock front with a powerful Zn He-alpha backlighter. The opacity along the Hugoniot is also deduced, which is essential as it changes significantly from its initial value. We will present results of first NIF experiments where we obtained absolute measurements of Hugoniot states from 120-650 Mbar, which is an order of magnitude greater than previously measured in CH (Cauble et al., PRL 1998). The measured EOS locus is consistent with previous data, and significantly stiffer than the theoretical EOS used for comparison. [Preview Abstract] |
Monday, November 11, 2013 4:24PM - 4:36PM |
CO6.00013: Material Release at High-Energy Densities P.M. Nilson, R. Betti, D.D. Meyerhofer, A. Shvydky, A.A. Solodov, P.A. Jaanimagi, D.H. Froula High-energy-density matter releases after an inertial time, creating nonideal plasmas with unique thermodynamic properties. Picosecond-resolution x-ray radiography and flash (100-ps) x-ray penumbral imaging were used to measure the release of metal targets heated by a powerful flux of energetic electrons or protons generated by the OMEGA EP Laser System. The data show target decompression over a nanosecond period after the initial target-heating phase. The measured plasma density profiles and target-release speeds were used to infer the pressure-density release isentropes. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944. [Preview Abstract] |
Monday, November 11, 2013 4:36PM - 4:48PM |
CO6.00014: Hydrodynamic Tunneling of 440 GeV SPS protons in Solid Material: Production of Warm Dense Matter at CERN HiRadMat Facility Naeem Ahmad Tahir, Juan Blanco Sancho, Ruediger Schmidt, Alaxander Shutov, Florian Burkart, Daniel Wollmann, Antonio Roberto Piriz Numerical simulations have shown that the range of 7 TeV LHC protons in solid matter will be significantly increased due to hydrodynamic tunneling [1-3]. For example, in solid copper and solid carbon, these protons and the shower can penetrate up to 35 m and 25 m, respectively. However, their corresponding static range in the two materials is 1 m and 3 m, respectively. This will have important implications on machine protection design.In order to validate these simulation results, experiments have been performed at the CERN HiRadMat facility using the 440 GeV SPS proton beam irradiating solid copper cylindrical target [4]. The phenomenon of hydrodynamic tunneling has been experimentally confirmed and good agreement has been found between the simulations and the experimental results. A very interesting outcome of this work is that the HiRadMat facility can be used to generate High Energy Density matter including Warm Dense Matter and strongly coupled plasmas in the laboratory.\\[4pt] References: [1] N.A. Tahir et al., J. Appl. Phys. 97 (2005) 083532. [2] N.A. Tahir et al., Phys. Rev. E 79 (2009) 046410. [3] N.A. Tahir etal., Phys. Rev. Special Topics Accel. Beams 15 (2012) 051003. [4] J. Blanco Sancho et al., Proceedings of IPAC 2013 Conf., Shanghai, China, 2013. [Preview Abstract] |
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