Bulletin of the American Physical Society
58th Annual Meeting of the APS Division of Plasma Physics
Volume 61, Number 18
Monday–Friday, October 31–November 4 2016; San Jose, California
Session UO8: Warm Dense Matter |
Hide Abstracts |
Chair: Luke Fletcher, Stanford University Room: 212 CD |
Thursday, November 3, 2016 2:00PM - 2:12PM |
UO8.00001: X-Ray Opacity Measurements of Solid Density Plasmas Justin Wark, Thomas Preston, Orlando Ciricosta, Sam Vinko, Patrick Hollebon, Hyun-Kyung Chung, Thomas Burian, Jaromir Chalupsky, Vojtech Vozda, Frank Hall, Christopher Spindloe, Ulf Zastrau, Georgi Dakovski, Michael Minitti Accurate opacity measurements of dense plasmas are scarce, in part owing to the difficulty in creating samples that are uniform in density and temperature, and the associated undertaking of an opacity measurement on a time-scale short compared with disassembly. Here we demonstrate that x-ray opacity information can be obtained from emissivity measurements of solid-density targets of varying but known thickness, irradiated by a sub-100-fsec x-ray pulse from LCLS. As the emission is generated by the creation of core-holes created by the FEL, and they are rapidly filled on a femtosecond time-scale, information is gleaned before any hydrodynamic motion. Comparision with simulations based on the SCFLY atomic-kinetics code reveal that the time-integrated emission data can provide a strong constraint on the opacity under well-defined conditions of density and temperature, and further demonstrate that the technique is relatively insensitive to x-ray pulse-length and spatial distribution. As an example we present measurements of the K-shell opacity of a solid-density magnesium plasma for all ion stages up to helium-like. [Preview Abstract] |
Thursday, November 3, 2016 2:12PM - 2:24PM |
UO8.00002: Ionic Transport Coefficients of Dense Plasmas without Molecular Dynamics J. Daligault, S.D. Baalrud, C.E. Starrett, D. Saumon, T. Sjostrom We present a theoretical model that allows a fast and accurate evaluation of ionic transport properties of realistic plasmas spanning from warm and dense to hot and dilute conditions, including mixtures [1]. This is achieved by combining a recent kinetic theory based on effective interaction potentials with a model for the equilibrium radial density distribution based on an average atom model and the integral equations theory of fluids. The model should find broad use in applications where nonideal plasma conditions are traversed, including inertial confinement fusion, compact astrophysical objects, solar and extrasolar planets, and numerous present-day high energy density laboratory experiments. [1] J. Daligault, S.D. Baalrud, C.E. Starrett, D. Saumon and T. Sjostrom, Phys. Rev. Lett. 116, 075002 (2016) [Preview Abstract] |
Thursday, November 3, 2016 2:24PM - 2:36PM |
UO8.00003: Thermal conduction study of warm dense aluminum by proton differential heating Y. Ping, G. Kemp, A. Mckelvey, A. Fernandez-Panella, R. Shepherd, G. Collins, H. Sio, J. King, R. Freeman, R. Hua, C. Mcguffey, J. Kim, F. Beg A differential heating platform has been developed for thermal conduction study (Ping et al. PoP 2015), where a temperature gradient is induced and subsequent heat flow is probed by time-resolved diagnostics. An experiment using proton differential heating has been carried out at Titan laser for Au/Al targets. Two single-shot time-resolved diagnostics are employed, SOP (streaked optical pyrometry) for surface temperature and FDI (Fourier Domain Interferometry) for surface expansion. Hydrodynamic simulations show that after \textasciitilde 15ps, absorption in underdense plasma needs to be taken into account to correctly interpret SOP data. Comparison between simulations with different thermal conductivity models and a set of data with varying target thickness will be presented. [Preview Abstract] |
Thursday, November 3, 2016 2:36PM - 2:48PM |
UO8.00004: First-principles calculations of dynamic transport properties for x-ray Thomson scattering experiments on warm dense aluminum Bastian B. L. Witte, Philipp Sperling, Siegfried H. Glenzer, Ronald Redmer X-ray Thomson scattering (XRTS) is an effective tool to determine plasma parameters, e.g., temperature and density, in the warm dense (WD) matter regime. Furthermore, transport coefficients are relevant for modeling, e.g., fusion experiments or the magnetic field generation in planets. Recently, the electrical conductivity was extracted for the first time from XRTS experiments on aluminum, isochorically heated by the Linac Coherent Light Source (LCLS) [1]. The measured spectrally resolved scattering signal shows a strong dependence on the electron interactions, which have to be treated beyond perturbation theory. We present results for the dynamic transport properties in WD aluminum using density-functional-theory molecular dynamics (DFT-MD) simulations. The choice of the exchange-correlation (XC) functional, describing the interactions in the electronic subsystem, has significant impact on the ionization potential and the thermal and electrical conductivity. The calculation of the XRTS signal from the DFT-MD simulations shows very good agreement with the LCLS data [1] if hybrid functionals are applied, i.e., XC functionals within the generalized gradient approximation are not suitable for the description of WD aluminum. [1] P. Sperling et al., Phys. Rev. Lett. 115, 115001 (2015) [Preview Abstract] |
Thursday, November 3, 2016 2:48PM - 3:00PM |
UO8.00005: Non-Drude conductivities in isochorically heated warm dense aluminum observed by inelastic x-ray scattering Philipp Sperling, Bastian Witte, Luke B. Fletcher, Eric Galtier, Eliseo J. Gamboa, Hae Ja Lee, Ulf Zastrau, Ronald Redmer, Siegfried H. Glenzer We have performed highly-resolved inelastic x-ray measurements in warm dense aluminum isochorically heated by 8~keV Linac Coherent Light Source (LCLS) photons. The inelastic forward scattering spectra resolve electronic density fluctuations (plasmons) that allow an accurate determination of the electron density, electron temperature, and for the first time the electrical conductivity [1]. The plasmon spectrum is strongly affected by the electron interaction that show plasmon damping smaller than calculated by Landau damping. We present density functional theory molecular dynamic (DFT-MD) simulations of the electrical conductivity of warm dense aluminum that show non-Drude conductivities and a reduced plasmon damping indicating electron-particle collisions as well as electron excitation. Translated into a plasmon spectrum we find a very good agreement with our measurements previously not achieved by standard perturbative theories due to an insufficient description of dissipative processes in strongly coupled plasmas. [1] P. Sperling {\it et al.}, Phys. Rev. Lett. {\bf 115}, 115001 (2015). [Preview Abstract] |
Thursday, November 3, 2016 3:00PM - 3:12PM |
UO8.00006: Isochoric heating of solid gold targets with the PW-laser-driven ion beams Sven Steinke, Qing Ji, Stepan Bulanov, John Barnard, Thomas Schenkel, Eric Esarey, Wim Leemans We present an end-to-end simulation for isochoric heating of solid gold targets using ion beams produced with the BELLA PW laser at LBNL: (i) 2D Particle-In-Cell (PIC) simulations are applied to study the ion source characteristics of the PW laser-target interaction at the long focal length (f/{\#}65) beamline at laser intensities of \textasciitilde 5x10$^{\mathrm{19}}$W/cm$^{\mathrm{2}}$ at spot size of $\omega _{\mathrm{0}}=$52 $\mu $m on a CH target. (ii) In order to transport the ion beams to an EMP-free environment, an active plasma lens [1] will be used. This was modeled by calculating the Twiss parameters of the ion beam from the appropriate transport matrixes using the source parameters obtained from the PIC simulation. Space charge effects were considered as well. (iii) Hydrodynamic simulations indicate that these ion beams can isochorically heat a 1 mm$^{\mathrm{3}}$ gold target to the Warm Dense Matter state. Ref: [1] J. van Tilborg \textit{et al}, Phys. Rev. Lett. \textbf{115}, 184802 (2015). [Preview Abstract] |
Thursday, November 3, 2016 3:12PM - 3:24PM |
UO8.00007: The generation of warm dense matter samples using pulsed-power generators P. A. Gourdain, C. E. Seyler, P. F. Knapp Warm dense matter (WDM) bridges the gap between plasma and condensed matter, with densities similar to that of a solid, but temperature on the order of 1 eV. WDM is key to understanding the formation of gaseous giants, Mega-Earths, planetary collisions and inertial fusion implosions. Yet, the quantum properties of WDM and how they are expressed at the macroscopic level are mostly unknown. This paper uses 3-dimensional numerical simulations to show that cm-scale WDM samples can be generated by pulsed-power machines using a \textit{fast }plasma closing switch, which virtually eliminates the mixing of WDM with other states of matter, allowing the measurement of its physical properties using line average diagnostics. A pre-ionized gas puff is imploded onto a central metal rod. Initially, most of the discharge current flows inside the gas shell. When the shell reaches the rod the full current switches to the rod in less than 10 ns. The subsequent compression produces WDM. We will discuss how an existing platform to generate cm-scale WDM at 20MA on the Z-machine at Sandia National Laboratories. [Preview Abstract] |
Thursday, November 3, 2016 3:24PM - 3:36PM |
UO8.00008: Ionic transport in strongly asymmetric mixtures: A crossover between classical and Lorentz diffusion Alexander White, Christopher Ticknor, Joel Kress, Lee Collins, Jean Clerouin, Alain Decoster, Nicolas Desbiens, Philippe Arnault We study how concentration changes transport properties along isobars-isotherms for a mixture of hydrogen and heavier elements, representative of turbulent layers relevant to inertial confinement fusion (ICF) and astrophysics. We perform large first principles orbital free molecular dynamics (OFMD) simulations and analyze the transport properties. Comparisons are made with transport theory in the kinetic and coupled regime. We demonstrate that the addition of a small amount of the heavy element in a light material has a dramatic effect on the correlation structure and on viscosity and diffusion in the mixture. This effect is explained through kinetic theory as a manifestation of a crossover between classical diffusion and Lorentz diffusion. [Preview Abstract] |
Thursday, November 3, 2016 3:36PM - 3:48PM |
UO8.00009: Atomistic study of mixing at high Z / low Z interfaces at Warm Dense Matter Conditions Tomorr Haxhimali, James Glosli, Robert Rudd We use atomistic simulations to study different aspects of mixing occurring at an initially sharp interface of high Z and low Z plasmas in the Warm/Hot Dense Matter regime. We consider a system of Diamond (the low Z component) in contact with Ag (the high Z component), which undergoes rapid isochoric heating from room temperature up to 10\textasciitilde eV, rapidly changing the solids into warm dense matter at solid density. We simulate the motion of ions via the screened Coulomb potential. The electric field, the electron density and ionizations level are computed on the fly by solving Poisson equation. The spatially varying screening lengths computed from the electron cloud are included in this effective interaction; the electrons are not simulated explicitly. We compute the electric field generated at the Ag-C interface as well as the dynamics of the ions during the mixing process occurring at the plasma interface. Preliminary results indicate an anomalous transport of high Z ions (Ag) into the low Z component (C); a phenomenon that is partially related to the enhanced transport of ions due to the generated electric field. These results are in agreement with recent experimental observation on Au-diamond plasma interface. (\textit{W. Bang et al., Sci. Rep. }\textbf{\textit{5}}\textit{, 14318 (2015) }) [Preview Abstract] |
Thursday, November 3, 2016 3:48PM - 4:00PM |
UO8.00010: Comprehensive Studies of Ultrafast Laser Excited Warm Dense Gold Zhijiang Chen, Mianzhen Mo, Brandon Russell, Ying Tsui, Xijie Wang, Andrew Ng, Siegfried Glenzer Isochoric excitation of solids by ultrafast laser pulses is an important approach to generate warm dense matter in laboratory. Electrical conductivity, structural dynamics and lattice stabilities are the most important properties in ultrafast laser excited warm dense matter. To investigate these properties, we have developed multiple advanced capabilities at SLAC recently, including the measurement of semi-DC electrical conductivity with ultrafast THz radiation, the study of solid and liquid structural dynamics by ultrafast electron diffraction (UED), and the investigation of lattice stability using frequency domain interferometry (FDI) on both front and rear surfaces. Due to the non-reversible nature in exciting solid to warm dense matter, all these diagnostics are implemented with single-shot approaches, reducing the uncertainties due to shot-to-shot fluctuations. In this talk, we will introduce these novel capabilities and present some highlighted studies in warm dense gold, which was uniformly excited by ultrafast laser pulses at 400nm. We appreciate the supports from DOE FES under FWP {\#}100182. [Preview Abstract] |
Thursday, November 3, 2016 4:00PM - 4:12PM |
UO8.00011: Path Integral Monte Carlo Simulations of Warm Dense Plasmas with mid-Z Elements Kevin Driver, Francois Soubiran, Shuai Zhang, Burkhard Militzer Theoretical studies of warm dense plasmas are crucial for improving our knowledge of giant planets, astrophysics, shock physics, and new plasma energy technologies, such as inertial confined fusion. Path integral Monte Carlo (PIMC) and density functional theory molecular dynamics (DFT-MD) provide consistent, first-principles descriptions of warm, dense matter over a wide range of density and temperature conditions. Here, we report simulation results for a variety of first- and second-row elements. DFT-MD algorithms are well-suited for low temperatures, while PIMC has been restricted to relatively high temperatures due to the free-particle approximation of the nodal surface. For heavier, second-row elements, we have developed a new, localized nodal surface, which allows us to treat bound states within the PIMC formalism. By combining PIMC and DFT-MD pressures and internal energies, we produce a coherent, first-principles equation of state, bridging the entire warm dense matter regime. Pair-correlation functions and the density of electronic states reveal an evolving plasma structure. The degree of ionization is affected by both temperature and density. Finally, shock Hugoniot curves show an increase in compression as the first and second shells are ionized. [Preview Abstract] |
Thursday, November 3, 2016 4:12PM - 4:24PM |
UO8.00012: Electrical and thermal properties of warm dense water created by isochoric heating of a submicron water sheet at FLASH. Jongjin Kim, Philipp Sperling, Zhijiang Chen, Sven Toleikis, Chandra Curry, Mianzhen Mo, Ronald Redmer, DePonte Daniel, Siegfried Glenzer The advent of XUV and x-ray free electron lasers has allowed for the development of crystallographic scattering experiments of aqueous species with high brilliance. The hydrodynamic expansion of water heated by an FEL was only recently demonstrated, but processes at shorter time scales have not been studied experimentally. Our research group uses time-resolved optical transmission and reflection measurements to determine fundamental electron transport properties of warm dense matter. This technique has been combined with a recently developed water sheet target. Isochoric heating by FLASH and optical probing requires a flat and windowless water target, with a thickness below a few microns. We describe the development and characterization of a water sheet jet target with thickness down to 200 nm, along with preliminary results with isochoric heating with FLASH operating near the water window. [Preview Abstract] |
Thursday, November 3, 2016 4:24PM - 4:36PM |
UO8.00013: Density measurements of dynamically-compressed, melting phase silicon via simultaneous in-situ x-ray diffraction and x-ray contrast imaging using the LCLS x-ray free electron laser at MEC Shaughnessy Brennan Brown, Hae Ja Lee, Bob Nagler, Eric Galtier, Zhou Xing, Arianna Gleason, Eduardo Granados, Inhhyuk Nam, Frank Seiboth, Andreas Schropp, Andrew Higginbotham, Akel Hashim, Brice Arnold, Alan Fry Studies of compressed silicon have extracted lattice parameters from in situ x-ray diffraction data [1, 2]. However, density measurements during high-pressure liquid melt remain difficult as the sample becomes amorphous and enters the warm dense matter regime. X-ray contrast imaging offers a powerful tool to resolve changes in density during laser-driven shock compression and enables imaging of regions before, between, and after elastic and plastic waves [3, 4]. This experiment utilizes the LCLS x-ray free electron laser and the Matter in Extreme Conditions instrument to obtain simultaneous x-ray diffraction and x-ray contrast imaging during dynamic shock loading. VISAR measurements on LiF and Si show the accessible pressure exceeding 1MBar. In this talk, we will present images of the elastic and plastic waves and discuss determination of the density profile of high-pressure melting phase silicon following the plastic deformation wave. [1] Wark et al. Phys. Rev. B 40(8) (1989) [2] Daisenberger et al. Phys. Rev. B 75(22) (2007) [3] Nagler et al. J. Synchrotron Rad. 22 (2015) [4] Schropp et al. Scientific Reports 5, 11089 (2015) [Preview Abstract] |
Thursday, November 3, 2016 4:36PM - 4:48PM |
UO8.00014: WDM production with intense relativistic electrons Josh Coleman, Heather Andrews, Mark Klasky, James Colgan, Trevor Burris-Mog, Dan Creveling, Craig Miller, Dale Welch, Mike Berninger The production of warm dense matter (WDM) through collisional heating with intense relativistic electrons is underway. A 100-ns-long monochromatic bunch of electrons with energies of 19.1-19.8 MeV and currents of 0.2-1.7 kA is used to heat 100-$\mu $m-thick foils with Z \textless 29. The principal objective of these experiments is to develop a controlled method of measuring the equation of state with particle beams and benchmark numerical models. Measurements indicate the formation of a warm dense plasma near the end of the pulse, which is on the order of the beam size. These plasmas expand 5 mm in the first microsecond and slow down to \textless 0.5 mm/$\mu $s over the next 10 $\mu $s. These plasmas also produce both emitted and absorbed spectra amongst a continuum for Ti, Fe, and Cu. Cu-I spectra is dominated by stark broadening, indicating a cool plasma with n$_{\mathrm{e}}$ \textgreater 10$^{\mathrm{18}}$ cm$^{\mathrm{-3}}$. At these densities our plasma is collisionally dominated making it possible to spectrally model the density and temperature in LTE. Preliminary density gradient measurements will also be presented indicating the spatial extent of the solid density cutoff. [Preview Abstract] |
Thursday, November 3, 2016 4:48PM - 5:00PM |
UO8.00015: Electron and ion dynamics study of iron in warm dense matter regime by time-resolved XAS measurements and from first-principles T. Ogitsu, A. Fernandez-PaƱella, A. Correa, K. Engelhorn, B. Barbrel, D. G. Prendergast, D. Pemmaraju, M. Beckwith, D. Kraus, S. Hamel, B. I. Cho, L. Jin, J. Wong, P. Heinman, G. W. Collins, R. Falcone, Y. Ping We present a study of the electron-phonon coupling of warm dense iron upon femtosecond laser excitation by time-resolved x-ray absorption near edge spectroscopy (XANES). The dynamics of iron in electron-ion non-equilibrium conditions was studied using ab-initio density-functional-theory (DFT) simulations combined with the Two Temperature Model (TTM) where spatial inhomogeneity of electron (and ion) temperature(s) due to short ballistic electron transport length in iron was explicitly taken into consideration. Detailed comparison between our simulation results and experiments indicates that the ion temperature dependence on specific heat and on electron-phonon coupling also plays a relevant role in modeling the relaxation dynamics of electrons and ions. These results are the first experimental evidence of the suppression of the electron-phonon coupling factor of a transition metal at electron temperatures ranging 5000-10000 K. This work was performed under DOE contract DE-AC52-07NA27344 with support from OFES Early Career program and LLNL LDRD program [Preview Abstract] |
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