Bulletin of the American Physical Society
50th Annual Meeting of the Division of Plasma Physics
Volume 53, Number 14
Monday–Friday, November 17–21, 2008; Dallas, Texas
Session UO4: High Energy Density Plasmas and Warm Dense Matter |
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Chair: Alexander Velikovich, Naval Research Laboratory Room: Reunion B |
Thursday, November 20, 2008 2:00PM - 2:12PM |
UO4.00001: Initial Experiments Using the OMEGA EP Laser System D.D. Meyerhofer, T.R. Boehly, R. Betti, V.Yu. Glebov, J.H. Kelly, J.P. Knauer, S.J. Loucks, R.L. McCrory, S.F.B. Morse, J.F. Myatt, P.M. Nilson, S.P. Regan, T.C. Sangster, V.A. Smalyuk, C. Stoeckl, W. Theobald The OMEGA EP Laser System was completed in April 2008 as a significant enhancement of the OMEGA Laser System. It consists of four NIF-like beamlines, two of which can be operated as high-energy petawatt laser beams. The initial experimental plan includes developing bright backlighter sources (line and bremsstrahlung), isochoric heating, hot-electron conversion-efficiency measurements (to compare with results from other systems), long-pulse LPI at NIF-relevant scale lengths, and fast-ignition integrated experiments using cone-in-shell targets. Backlighter experiments are designed to optimize the fluence for cryogenic implosion core radiography. This talk will describe the current status of the OMEGA~EP Laser System and some initial target-physics experiments. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302. [Preview Abstract] |
Thursday, November 20, 2008 2:12PM - 2:24PM |
UO4.00002: Isentropic-Compression Equation-of-State Experiments Using the OMEGA Laser D.E. Fratanduono, M.A. Barrios, T.R. Boehly, D.D. Meyerhofer, D.G. Hicks, J.H. Eggert, R. Smith Quasi-isentropic compression of materials can improve the understanding of equation of state (EOS) by providing off-Hugoniot measurements.~ Quasi-isentropic compression was used on the OMEGA Laser System to achieve peak pressures $>$10 Mbar in diamond and at relatively low temperatures of $<$1 eV. We report on a technique that uses this compression to study structural and optical properties of materials' high pressures. The reflectivity of aluminum samples is observed to dramatically decrease when compressed to $\sim $1 Mb. Several explanations for this will be discussed. This work was supported by U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302. [Preview Abstract] |
Thursday, November 20, 2008 2:24PM - 2:36PM |
UO4.00003: Precision Equation-of-State (EOS) Measurements Using Laser-Driven Shock Waves Using the OMEGA Laser M.A. Barrios, D.E. Fratanduono, T.R. Boehly, D.D. Meyerhofer, D.G. Hicks, J.H. Eggert, P.M. Celliers Recent advances in diagnostics and analysis enables highly precise measurements of material properties at very high pressures. When quartz is used as a standard (reference) material for impedance-matched experiments with transparent samples, VISAR is able to track the shock velocity throughout the experiment. This enables the velocities at the impedance-matched point to be determined with an uncertainty of $\sim $1{\%}. Similarly, the effects of steadiness and curvature can readily be evaluated. These refinements provide precision EOS data previously unattainable at these high pressures. We report on EOS measurements (at 1 to 10 Mbar) performed at the OMEGA Laser Facility. This work was supported by U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302. [Preview Abstract] |
Thursday, November 20, 2008 2:36PM - 2:48PM |
UO4.00004: Conductivity measurements of multi-shock compressed deuterium J.R. Rygg, D.G. Hicks, R.F. Smith, G.W. Collins, O.L. Landen, T.R. Boehly The transport properties of compressed hydrogenic materials affect the stability of accelerating inertial confinement fusion targets and the structure of gas-giant planets. Calculation of the electrical and thermal conductivities of hydrogen and deuterium is particularly challenging in the region of transition from an insulating molecular to a metallic state (near 1 MBar and several thousand K), because in this region the conductivities change by several orders of magnitude. Deuterium samples were compressed through this region up to multiple MBar by a sequence of laser-driven shocks. Results of simultaneous pressure, temperature, and optical reflectivity measurements of these samples will be reported. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. IM {\#}LLNL-ABS-405478. [Preview Abstract] |
Thursday, November 20, 2008 2:48PM - 3:00PM |
UO4.00005: Study of material properties under extreme pressure and strain rates using laser driven ramped drives Hye-Sook Park, Bruce Remington, Joel Bernier, Richard Becker, Robert Cavallo, Steve Pollaine Material properties under extreme pressure ($>$1 Mbar) are of great interest to the material science community as well as the astro-planetary sciences. We are developing an experimental technique that can compress materials quasi-isentropically at very high pressures and ultrahigh strain rates using high power lasers such as the Omega laser system at Rochester, NY and eventually on NIF at Livermore, CA. Omega lasers can reach up to 2 Mbar and we expect to achieve $>$10 Mbar with NIF [H. S. Park et al., JPCS, \textbf{112}, 042024 (2008)]. We have studied the material properties by measuring the growth factors on the artificially induced sinusoidal target samples via Rayleigh-Taylor hydrodynamic instabilities. We utilize face-on radiography taken with the laser-driven x-ray backlighters. This paper will present our recent work on vanadium especially focusing on the grain boundary effects on the growth rate. Our results will be compared to the crystal plasticity model and the various material strength models. [Preview Abstract] |
Thursday, November 20, 2008 3:00PM - 3:12PM |
UO4.00006: Simulations of a 5 Mbar, indirect-drive strength platform for use on the National Ignition Facility Shon T. Prisbrey, Robert M. Cavallo, Hye-Sook Park, Bruce A. Remington A key component of being able to measure the strength of materials at high strain rates and pressures is the ability to create the necessary environment. One viable platform that places material into a solid state at high pressures and strain rates is that of a shock unloading from a reservoir and piling up against a sample (Edwards et al., \textbf{92} PRL 2004). We will present simulation results from a proposed indirectly-driven reservoir for the National Ignition Facility that unloads across a gap to create a ramped pressure in a tantalum sample with a peak pressure of over 5 Mbar. We will also present calculated X-ray transmission radiographs of simulated Rayleigh-Taylor growth of rippled Ta with different strength models applied to the Ta. [Preview Abstract] |
Thursday, November 20, 2008 3:12PM - 3:24PM |
UO4.00007: Time-resolved x-ray scattering measurements of shock propagation in laser-driven CH foils Benjamin Barbrel, Michel Koenig, Alessandra Benuzzi-Mounaix, Erik Brambrink, Colin Brown, Fida Khattak, Bob Nagler, Marc Rabec-le-Gloaec, Chris Spindloe, Marc Tolley, Samuel Vinko, David Riley, Justin Wark, Gianluca Gregori We have performed time-resolved x-ray scattering measurements in the warm dense matter regime at the LULI 2000 laser facility (Ecole Polytechnique, France). The laser-driven shocked CH samples were probed with 30ps, 8keV Cu Kalpha radiation, delayed with respect to the shock propagation. The angularly resolved scattered x-ray signal, collected over a wide angle range (25-55 degrees), gives access to the plasma structure factor. For the first time, the use of a short pulse x-ray source allows ourselves to probe the microscopic properties of WDM at different plasma conditions as the shock travels. Spectrum shows evidence of strong coupling behaviour in the CH plasma. Results are compared to simulations taking account strong coupling effect and appropriate multi ionic-species treatment. The data analysis and the models used will be presented and discussed. [Preview Abstract] |
Thursday, November 20, 2008 3:24PM - 3:36PM |
UO4.00008: X-ray sources for radiography of warm dense matter Alessandra Benuzzi-Mounaix, Erik Brambrink, Benjamin Barbrel, Michel Koenig, Chris Gregory, B\'er\'enice Loupias, Alessandra Ravasio, Marc Rabec le Gloahec, Tommaso Vinci, Tom Boehly, Takashi Endo, Tomoaki Kimura, Norimasa Ozaki, Huigang Wei, Yefim Aglitskiy, Anatoly Faenov, Tatiana Pikuz The knowledge of Warm Dense Matter is important in different domains such as inertial confinement fusion, astrophysics and geophysics. The development of techniques for direct probing of this type of matter is of great interest. X-ray radiography is one of the most promising diagnostic to measure density directly. Here we present some results of low-Z material radiography and an experiment devoted to characterize a short pulse laser driven hard x-ray source for the radiography of medium and high Z matter. Experiments have been performed on LULI2000 and TW facilities at the Ecole Polytechnique. [Preview Abstract] |
Thursday, November 20, 2008 3:36PM - 3:48PM |
UO4.00009: Ab initio benchmarking of the thermal conductivity models for hydrogen under ICF conditions Jean Clerouin, Vanina Recoules, Flavien Lambert, Benoit Canaud, Alain Decoster We present the first ab initio evaluation of the thermal conductivity of hydrogen for a density ($\rho$ = 80 g/cc) and in a range of temperatures (50 eV $<$ T $<$ 1000 eV) which corresponds to the Inertial Confinement Fusion regime. Such simulations are made possible by the use of nearly coulombic pseudo-potentials whith a high cutoff in energy, and by the high density which translates into a moderate T/T$_F$ ratio (where T$_F$ is the Fermi temperature), and thus a moderate number of electronic orbitals to consider. With rising temperature, the hydrogen plasma evolves from the strongly coupled degenerate regime ($\Gamma=14$) to the kinetic semi-degenerate regime. The thermal conductivity is computed from the general Kubo-Geenwood expression of the Onsager relations for transport coefficients. Results are compared with the usual Lee-More and Spitzer-Hubbard formulations. [Preview Abstract] |
Thursday, November 20, 2008 3:48PM - 4:00PM |
UO4.00010: Characterization of warm dense matter produced by laser-accelerated high-energy protons M. Nakatsutsumi, J. Fuchs, A. Mancic, J. Robiche, P. Renaudin, P. Combis, F. Dorchies, M. Harmand, G. Maynard, J. Vassaux, P. Mora, P. Antici, S. Fourmaux, P. Audebert Producing warm dense plasmas (WDM: solid density, few eV $\sim $ few 10s eV) is of interest for fundamental plasma physics or ICF. Laser-produced proton heating is of interest since they are short ($<$1ps) and deposit their energy volumetrically. Experiments were performed using the LULI 100 TW facility to create and characterize WDM. We used, (i) 2D time-resolved optical self-emission of the heated target, (ii) surface expansion velocity measurement through phase measurements of a reflecting probe beam, and (iii) x-ray absorption spectroscopy. We showed that we could produce quasi-uniform heating of solids, as suited for e.g. EoS measurements. Time-resolved solid-liquid-plasma transition has been measured, as well as energy-loss of MeV protons in warm dense plasmas. [Preview Abstract] |
Thursday, November 20, 2008 4:00PM - 4:12PM |
UO4.00011: Photoionized Plasmas Created by Soft X-Ray Laser Irradiation of Solid Targets Mark Berrill, Fernando Brizuela, Benjamin Langdon, Herman Bravo, Carmen Menoni, Jorge J. Rocca We report the first study of warm plasmas created by photoionization of solid targets with focused soft x-ray laser pulses, in which single photon photoionization is the dominant energy absorption mechanism. Laser pulses of 1 ns duration from a 46.9 nm capillary discharge laser were focused on low absorption (silicon), and high absorption (chromium, and silver) targets. The emitted plasma radiation was spectroscopically analyzed and compared to simulations using a 1 1/2 D hydrodynamic/atomic model. Spectra agree with simulations in showing that the Si plasmas are significantly colder and less ionized, confirming that in contrast to plasmas created by optical lasers the plasma properties are largely determined by the absorption coefficient of the target material. Work supported by the NNSA SSAA program through U.S. DOE Grant No. DE-FG52-06NA26152, using facilities from the NSF ERC Center for Extreme Ultraviolet Science and Technology, NSF Award Number EEC-0310717. M.B. was supported by DOE CSGF Grant No. DE-FG02-97ER25308. [Preview Abstract] |
Thursday, November 20, 2008 4:12PM - 4:24PM |
UO4.00012: Single-Shot Optical Conductivity Measurements of Dense Aluminum Plasma Irina Churina, Byoung-ick Cho, Aaron Bernstein, Todd Ditmire The dielectric function of dense aluminum in the 0.1-1.5eV range was measured using frequency-domain interferometry with chirped pulses, by simultaneously measuring the optical probe reflectivity and phase shift from the rear surface of femtosecond heated aluminum foils. The optical conductivity of dense warm aluminum was extracted, based on the sharp interface at a dense plasma surface, and found to agree with calculations based on a model by Lee and More. Both free and bound electron contributions to the optical conductivity were taken into account in our calculation. The measured imaginary part of optical conductivity in this temperature range showed Ohmic like behavior. Using direct laser heating of a metal film we were able to generate electron thermal conduction waves that allowed us to create and measure the state of warm but still dense aluminum. [Preview Abstract] |
Thursday, November 20, 2008 4:24PM - 4:36PM |
UO4.00013: High Energy Density Physics Research Using Intense Ion Beams: the HEDgeHOB Collaboration N.A. Tahir, A. Shutov, I.V. Lomonosov, A.R. Piriz, D.H.H. Hoffmann, C. Deutsch Intense particle beams provide a novel tool to generate large samples of HED matter with uniform physical conditions [1]. Theoretical studies have shown that an ion beam can be employed using different experimental schemes to study HED states in matter. These include {\bf HIHEX}~[2,3] and {\bf LAPLAS}~[4,5]. The former involves isochoric and uniform heating of matter by an ion beam that is followed by isentropic expansion of the heated material. This allows one to access the entire phase diagram including those regions which can not be accessed by traditional methods of shock waves. The latter considers a multiple shock reflection technique that leads to a low-entropy compression of a test material like H or water which generates physical conditions that are expected to exist in the interior of giant planets. Interesting problems like Rayleigh-Taylor and Richtmyer-Meshkov instabilities have also been investigated in detail.This work has provided the necessary basis for the {\bf HEDgeHOB} proposal for future experiments at the {\bf FAIR} facility at Darmstadt. [1] N.A. Tahir et al., PRE 60 (1999) 4715. [2] D.H.H. Hoffmann et al., PoP 9 (2002) 3652. [3] N.A. Tahir et al., PRL 95 (2005) 035001. [4] N.A. Tahir et al., PRE 62 (2001) 016402. [5] N.A. Tahir et al., Nucl. Instr. Meth. A 577 (2007) 238. [Preview Abstract] |
Thursday, November 20, 2008 4:36PM - 4:48PM |
UO4.00014: Measurements of Radiative Shock Properties using Xray Thomson Scattering A. Visco, R.P. Drake, M.J. Grosskopf, S.H. Glenzer, D.H. Froula, A.B. Reighard Radiative shocks are shock waves whose structure has been altered by radiation transport from the shock-heated matter. Such shocks are present in numerous astrophysical systems, including supernova remnants, supernovae, and accretion disks. Recent experiments have used the Omega laser to study radiative shock systems that are optically thin upstream and optically thick downstream. A thin slab of low-Z material is driven into a 1.1 atm. cylinder of high-Z gas at speeds $>$ 100 km/s, producing strong radiative effects. Energy lost to radiation escaping upstream causes the shock to collapse spatially, producing a thin dense shell. X-ray Thomson scattering is employed, in the Compton scattering regime, to measure the electron temperature and ionization in the shocked matter. The experiment used emission from a Mn x-ray source at 6.15 and 6.18 keV, oriented to produce scattering at angles near 100 degrees. The x-ray spectrum was detected using a crystal spectrometer and a gated, multi-strip, microchannel-plate detector. Measured results will be shown, and the inferred properties will be compared with results of simulations and analytic estimates. [Preview Abstract] |
Thursday, November 20, 2008 4:48PM - 5:00PM |
UO4.00015: Novel Condensed Matter Cluster High Reaction Rate ICF Target George Miley Recent research has developed a technique for imbedding high density condensed matter deuterium ``clusters'' (50-100 atoms per cluster) in various metals such as Palladium (Pd), Boron (B) and Lithium (Li) [1]. Experiments have shown that these condensed matter clusters approach metallic conditions, exhibiting super conducting properties. An ICF target is proposed where a central core is designed with a material containing these clusters. A conventional ablator-tamper surrounds the core. Preliminary computations indicate that a large percentage of the clusters should reach compressed densities exceeding that of conventional cryogenically-fueled deuterium targets. The reaction rate from the compressed clusters then becomes very high while the total yield depends upon the cluster packing fraction achieved. Such a target potentially offers higher reaction rates and higher fractional burns than possible with conventional targets. Key issues under study are whether adequate cluster density per unit volume can be fabricated in the target core, cluster stability during compression, and radiation losses due to the high Z. [1] G. H. Miley, ``Novel High Performance Cluster Type ICF Target'', DOE ICC Workshop, Reno NV, June 2008. [Preview Abstract] |
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