Bulletin of the American Physical Society
2006 48th Annual Meeting of the Division of Plasma Physics
Monday–Friday, October 30–November 3 2006; Philadelphia, Pennsylvania
Session QO3: High-Energy-Density Science |
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Chair: Mike Desjarlais, Sandia National Laboratories Room: Philadelphia Marriott Downtown Grand Salon KL |
Wednesday, November 1, 2006 2:00PM - 2:12PM |
QO3.00001: Shock waves in solids driven by ultra-fast laser heating Yasuhiko Sentoku, Andreas Kemp, Radu Presura, Michael Bakeman, Thomas Cowan We are studying heating of thin foils by ultra-intense laser irradiation using collisional two-dimensional particle-in-cell simulations. We find that the laser-generated hot electron population is confined laterally by resistive magnetic fields and heats the target beyond keV electron temperatures isochorically. Using this confinement one can excite controlled shock waves that compress the plasma even beyond solid density. Such shocks can be launched at material interfaces inside the target where jumps in the average ionization state and thus electron density lead to Gigabar pressure. They can propagate stably over picoseconds, and the ion thermal energy after the shocks can exceed 1 keV at compressed solid density. A significant enhancement of the thermal neutron yield compared to uniform targets can be expected. This mechanism might provide thermal neutron sources for fusion studies and such extreme plasmas have the potential to be a good testbed for high energy density physics. [Preview Abstract] |
Wednesday, November 1, 2006 2:12PM - 2:24PM |
QO3.00002: Observation of ionization shifts in K-shell emission from short-pulse laser irradiated micro-dot targets Paul Neumayer, Andrea Kritcher, Otto Landen, Haeja Lee, Dustin Offerman, Eric Shipton, Siegfried Glenzer X-ray Thomson scattering using short pulse laser generated intense line radiation has a great potential as a time-resolved temperature and density diagnostic for high-energy density states of matter. We present recent results characterizing Chlorine K-alpha and K-beta line emission obtained by irradiating Saran foil with 50 Terawatt laser pulses from the Callisto laser (Jupiter Laser Facility, Lawrence Livermore National Laboratory). Spectra from front and rear side emission are recorded simultaneously with high resolution HOPG spectrometers employing imaging plate detectors. Conversion efficiencies of laser pulse energy into x-ray line emission of several 10$^{-5}$ are achieved and are maintained throughout up to 7 J of laser energy, thus constituting a short pulsed narrow band x-ray source of more than 10$^{11}$ photons. When the target size is reduced to 50 micrometer (``micro-dot'') a significant blue-shift of up to 5 eV is clearly observed. This can be attributed to higher ionization states of the target atoms indicating achievement of a high-temperature solid density state. This work was performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48 and LDRD 05-ERI-003. [Preview Abstract] |
Wednesday, November 1, 2006 2:24PM - 2:36PM |
QO3.00003: Intense Laser Cluster Interaction: Quasi-monoenergetic High Energy Ion Production Ayush Gupta, Thomas Antonsen, John Palastro, T. Taguchi We investigate the production of energetic ions in the interaction of intense short laser pulses with gases of van der Waals bound nanoscale atomic clusters using a 2-D electrostatic particle-in-cell (PIC) code [1-2]. The clustered gas strongly absorbs the laser pulse energy efficiently producing x-rays, extreme ultraviolet radiation, energetic particles and fusion neutrons. Cluster heating in an intense field is dominated by a collision-less resonant absorption process that involves energetic electrons transiting through the cluster. Cluster ions are accelerated by the space charge field created by the extraction of energetic electrons. Our simulations show that strong electron heating is accompanied by the generation of a quasi mono-energetic high-energy peak in the ion kinetic energy distribution function. We will present the mechanism for emergence of a beam-like ion energy distribution with high-energy ions. \newline [1] Taguchi, T., et al., Physical Review Letters, 2004. \textbf{92}(20) \newline [2] Antonsen, T.M., et al., Physics of Plasmas, 2005. \textbf{12}(5) [Preview Abstract] |
Wednesday, November 1, 2006 2:36PM - 2:48PM |
QO3.00004: Asymmetric explosion of laser-irradiated Hydrogen gas cluster plasmas Yu-hsin Chen, Sanjay Varma, Vinod Kumarappan, Howard Milchberg We present the results of an experiment in which we irradiate small clusters of Hydrogen gas molecules with intense, variable width sub-picosecond laser pulses. The hydrogen clusters are thought to undergo coulomb explosion after laser electric field ionization, and therefore should emit ions in a uniform angular distribution. However, using time-of-flight measurements, we have found that ions are emitted preferentially in the direction of polarization of the laser pulse. This asymmetric behavior is characteristic of much larger inert gas clusters with highly charged ions. We explore the dependence of the asymmetry on pulse duration, laser energy and cluster size. We also use a new two-arm time-of-flight detector setup to examine angular distributions for fixed laser polarization. Finally, we use Single-shot Supercontinuum Spectral Interferometry [1] to measure pump-induced transient index change for much greater hydrogen cluster densities in order to extract anisotropies in the real and imaginary cluster polarizabilities. \newline [1] K.Y. Kim, I. Alexeev, and H.M. Milchberg, Appl. Phys. Lett. 81, 4124 (2002). [Preview Abstract] |
Wednesday, November 1, 2006 2:48PM - 3:00PM |
QO3.00005: Enhanced Third Harmonic Generation from Anisotropically Expanding Clusters. Bonggu Shim, Greg Hays, Rafal Zgadzaj, Todd Ditmire, Michael Downer We report controlled enhancement of optical third harmonic generation (THG) from hydrodynamically expanding Ar clusters (6 x 10$^{5}$ atoms per cluster) several hundred femtoseconds following ionization and heating by ultrashort pump pulses. A 400 nm, 100 fs pump beam ionized a gas jet composed of Ar clusters and residual gas. An 800 nm, 100 fs probe then generated third harmonic radiation from expanding clusters at controlled delays. Simulations show that the nonlinear third order susceptibility of individual clusters and the THG coherence length of the clustered plasma medium were optimized nearly simultaneously as the pre-heated clusters expanded, and both contributed to the observed THG enhancement. When resonantly enhanced, THG developed temporary polarization anisotropy, showing that the clusters expanded faster along the pump polarization. By contrast, the linear optical response was isotropic. The physical mechanisms contributing to enhanced THG are scalable to relativistic probe intensity and to high-order harmonics extending to the soft x-ray regime. [Preview Abstract] |
Wednesday, November 1, 2006 3:00PM - 3:12PM |
QO3.00006: Low Velocity Ion Stopping for Warm Dense Matter Production Claude Deutsch In order to identify the basic interaction mechanisms underlying the production of strongly coupled plasmas with solid density and eV temperature through thin foils heating by intense and heavy ion beams with 0.3$<$E/A$<$3 MeV/amu we first confirm with a harmonic oscillator model of bound target electrons that maximum energy transfer occurs around 100 keV/amu beam energy.Plasma stopping is considered by including high velocity stopping on target ions and exact connections between low velocity stopping and particule diffusion. Magnetized targets are also considered. Multiple ion beam scattering on target particles is seen to play an important role in the evaluation of beam penetration depth into target. [Preview Abstract] |
Wednesday, November 1, 2006 3:12PM - 3:24PM |
QO3.00007: Shock-induced melting of crystalline carbon P.M. Celliers, J.H. Eggert, T.R. Boehly, J.E. Miller, A.V. Hamza, R.J. Wallace, D.K. Bradley, G.W. Collins, D.G. Hicks One of the ablator candidates for the capsule in the NIF Ignition Campaign is chemical vapor deposited crystalline carbon with nanocrystalline grain structure. Modeling of this ablator material requires accurate knowledge of the Hugoniot equation of state and of the location of the melt transition under shock. Using a line-imaging VISAR and a streaked optical pyrometer we have measured the luminosity of laser-driven shocks as a function of shock strength in CVD crystalline carbon in the pressure range 0.6 -3 TPa. There is a clear discontinuity in the shock emission when the shock amplitude decays into the solid-liquid mixed-phase coexistence region. From these data, along with previously measured Hugoniot data, we find that shock melting occurs between 700 and 1040 GPa along the Hugoniot at temperatures 8000 -10000 K, and that the Clapeyron slope, dP/dT is negative along the melt. The latter result indicates that liquid-phase carbon is denser than solid-phase carbon at these conditions. [Preview Abstract] |
Wednesday, November 1, 2006 3:24PM - 3:36PM |
QO3.00008: Thermal and Kinematic Equation-of-State Experiments Using Decaying Shock Waves J.E. Miller, T.R. Boehly, A. Melchoir, D.D. Meyerhofer, P.M. Celliers, J.H. Eggert, D.G. Hicks Thermal (temperature) measurements have been related to kinematic properties (pressure, density, and internal energy) over a wide range of pressures using decaying shocks. Unsupported laser-generated shocks from OMEGA are launched into a transparent material, and the evolution of the shock velocity and self-emission from the shock are measured. Using an absolutely calibrated pyrometer for the temperature and the known principal Hugoniot for the material, the shock velocity is related to the kinematic and thermal properties of the material. The relationship between these measurements and material models will be discussed. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-92SF19460. [Preview Abstract] |
Wednesday, November 1, 2006 3:36PM - 3:48PM |
QO3.00009: X-ray scattering measurements of Plasmons in solid density plasmas Siegfried Glenzer, O.L. Landen, P. Neumayer, R.W. Lee, K. Widmann, S.W. Pollaine, G. Gregori, A. Hoell, T. Bornath, V. Schwarz, R. Thiele, W.-D. Kraeft, R. Redmer We have developed a novel collective x-ray scattering technique to measure the physical properties of dense matter including temperature, density, and ionization state. The forward scattering spectrum of a laser-produced narrow-band x-ray line from isochorically heated solid-density beryllium has shown the plasmon resonance whose frequency position is a sensitive measure of the electron density. Moreover, dynamic structure calculations indicate that collisions, detailed balance, and Landau damping affect the shape of the plasmon spectrum. This technique will enable new applications to determine the equation of state and compressibility of dense matter. [Preview Abstract] |
Wednesday, November 1, 2006 3:48PM - 4:00PM |
QO3.00010: HEDgeHOB: High Energy Density Matter Generated by Heavy Ion Beams at the Future Facility for Antiprotons and Ion Research at Darmstadt Naeem Tahir, A. Shutov, I.V. Lomonosov, V. Kim, V.E. Fortov, A.R. Piriz, G. Wouchuk, D.H.H. Hoffmann A novel method for studying high-energy-density (HED) matter that involves isochoric and uniform heating of matter by intense ion beams has been proposed. The Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt is a unique laboratory world wide whose heavy ion synchrotron (SIS-18) delivers intense heavy ion of different species including uranium. The construction of the new Facility for Antiprotons and Ion Research (FAIR) will lead to an increase in beam intensity by two orders of magnitude and it will deposit hundreds of kJ/g specific energy in solid material. This will open up the way to study equation-of-state (EOS) properties of different phases of HED matter including strongly coupled plasmas$^{1,2}$. Use of a hollow beam with an annular focal spot$^3$ will allow low entropy compression of materials like hydrogen to create physics conditions that are expected to exist in the interiors of giant planets$^{4,5}$. References $^1$N.~A.~Tahir et al., Phys. Rev. Lett. 95, 035001 (2005). $^2$N.~A.~Tahir et al., High Energy Density Physics 2, 21 (2006). $^3$A.~R.~Piriz et al., Plasma Phys. Controlled Fusion 45, 1733 (2003). $^4$N.~A.~Tahir et al., Phys. Rev. E 62, 016402 (2001). $^5$A.~R.~Piriz et al.,Phys. Rev. E 66, 056403 (2002). [Preview Abstract] |
Wednesday, November 1, 2006 4:00PM - 4:12PM |
QO3.00011: Equation of state and Electrical resistivity of hot expanded Al-Au mixture Jean Clerouin, Vanina Recoules, Stephane Mazevet, Patrick Renaudin, Pierre Noiret The equation of state and the electrical resistivity of hot expanded Al-Au mixture are obtained in the internal energy range 5-50 MJ/kg. The experimental data were measured using a homogeneous and thermally equilibrated media produced inside an isochoric plasma closed-vessel, allowing an unequivocal test of the validity of the equation of state and transport coefficients modelling in warm dense matter regime. Experimental results were compared with quantum molecular dynamics simulations. The theoretical results match well the experimental data allowing a detailed interpretation of the theoretical thermodynamic properties and frequency-dependant conductivities, depending on the relative proportion of the mixture. [Preview Abstract] |
Wednesday, November 1, 2006 4:12PM - 4:24PM |
QO3.00012: Density Functional Theory simulations of water: phase-diagram and electrical conductivity Thomas R. Mattsson, Michael P. Desjarlais Knowledge of the properties of water is essential for correctly describing the physics of giant planets as well as shock waves in water. By using finite temperature density functional theory (DFT) we have investigated the structure and electronic conductivity of water across three phase transitions (molecular liquid/ ionic liquid/ superionic/ electronic liquid). There is a rapid transition to ionic conduction at 2000 K and 2 g/cm$^3$ while electronic conduction dominates at temperatures at and above 6000 K. We predict that the fluid bordering the superionic phase is conducting above 4000 K and 100 GPa [1]. Earlier work instead has the superionic phase bordering an insulating fluid, with a transition to metallic fluid not until 7000 K and 250 GPa. The LDRD office at SNL supported this work. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. \newline [1] T.R. Mattsson and M.P. Desjarlais, Phys. Rev. Lett. 97, 017801 (2006). [Preview Abstract] |
Wednesday, November 1, 2006 4:24PM - 4:36PM |
QO3.00013: Recent Dynamic Materials Experiments at the Trident Laser Facility Eric Loomis, Damian Swift, Shengnian Luo, Richard Kraus, Scott Greenfield, Dennis Paisley, Randy Johnson The Trident laser facility is the primary workhorse for conducting laser-induced shock physics experiments at Los Alamos National Laboratory (LANL). The pulse shaping flexibility of the Trident laser allows us to investigate dynamic material response through different material state and timescale regimes. Recent experiments were conducted on Be foils at low to moderate pressures to investigate shock front roughening of Be for usage as an inertial confinement fusion (ICF) ablator. Simultaneous line imaging Doppler velocimetry (VISAR) and surface displacement interferometric measurements were used to observe grain motion in the direction of the shock and to calibrate numerical models. Confined laser ablation studies have also been conducted to demonstrate and refine an alternate method to direct laser ablation. In the confined laser ablation technique the laser light is shined through a transparent substrate and deposited in a thin ablating medium such as C. The expansion of the ablating material is constrained on one side by the substrate providing a greater push into the target material. Ramped and square pulses have been used to induce isentropic compression and shock waves into the target respectively. \textit{In-situ} line VISAR measurements were made to quantify the loading history and to compare to simulations. [Preview Abstract] |
Wednesday, November 1, 2006 4:36PM - 4:48PM |
QO3.00014: Isochoric Heating of Reduced Mass Targets by Ultra-Intense Lasers as a Means of Creating Kilovolt Plasmas at Solid Densities Scott Wilks, Richard Klein, Steven Moon, Pravesh Patel, Bruce Remington, Ronnie Shepherd, Hyun-Kyung Chung, Gianlucca Gregori, Sophia Chen, Sigfried Glenzer, Stephanie Hansen, Andrew Mackinnon, Richard Snavely, Mike Key Recent results using a novel target design that allows material high temperature ($\sim $ 1 keV) solid density plasmas to be created using ultra-intense laser pulses will be presented. Targets composed of titanium and tamped with aluminum were irradiated with $\sim $ 100 Joule, 1 and 10 picosecond laser pulses. Significant increases in temperature over standard foil targets were observed. Using refined energy conservation arguments presented last year at this meeting, theoretical predictions of achievable temperatures are compared against temperatures inferred from experimental data. Predictions for plastic, titanium, and copper targets irradiated by a wide range of laser parameters will also be presented. [Preview Abstract] |
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