Bulletin of the American Physical Society
56th Annual Meeting of the APS Division of Plasma Physics
Volume 59, Number 15
Monday–Friday, October 27–31, 2014; New Orleans, Louisiana
Session NO6: HEDP Hydrodynamics |
Hide Abstracts |
Chair: Stephanie Hansen, Sandia National Laboratories Room: Galerie 3 |
Wednesday, October 29, 2014 9:30AM - 9:42AM |
NO6.00001: Perturbation Growth Seeded by a Metal Foam S.G. Glendinning, K.L. Baker, A.W. Cook, D.M. Doane, T.R. Dittrich, S.A. Felker, R.M. Seugling, S.A. Maclaren, A.S. Moore, S. McAlpin We have designed experiments for the Omega laser investigating the growth of pertubations between a Cu foam (density $\sim$ 1 g/cc) and a carbonized resorcinol formaldehyde (CRF) foam (density $\sim$ 0.05 g/cc). The interface between the two foams is impulsively accelerated by a 1 ns (7.5 kJ) laser drive in a gold hohlraum (peak T$_{\mathrm{R}}$ $\sim$ 185 eV). The growth is seeded by internal structures in the Cu foam that are characterized by x-ray tomography. Because of the strong dependence of viscosity on ionization, the Cu plasma is expected to have a much lower viscosity (and higher Reynolds number) than a comparable experiment with plastic in place of the Cu, and the Cu experiment is predicted to quickly become turbulent. We have simulated this experiment with the radiation-hydrodynamics code LASNEX (integrated hohlraum simulations). Various void structures were then simulated using the codes KULL and MIRANDA to test the effect of differing initial conditions. [Preview Abstract] |
Wednesday, October 29, 2014 9:42AM - 9:54AM |
NO6.00002: Mix Width Measurements of Accelerated Copper Foam Danielle Doanne, Kevin Baker, Gail Glendinning, Tom Dittrich, Sean Felker, Steve MacLaren, David Martinez, Rich Seugling, Alastair Moore, Stuart McAplin, Chuck Sorce, Nicholas Whiting We present results from a mix experiment conducted on the OMEGA laser, where a reduced density copper (Cu) foam, 1 g/cc, was accelerated into a low density material, carbonized resorcinol formaldehyde (CRF) at 50 mg/cc. The Cu foams, which could contain voids as large as 5 to 10 $\mu$m, were characterized via x-ray computed tomography. The mixing in the experiment is predicted to rapidly become turbulent. The experiment addresses whether the mix width is determined by the void structure in the foam itself. For these experiments the OMEGA laser is used to drive a halfraum up to a radiation temperature of $\sim$ 190 eV using a 1 ns flat top drive with 5 kJ of total laser energy to provide the ablation pressure for the foam. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344. [Preview Abstract] |
Wednesday, October 29, 2014 9:54AM - 10:06AM |
NO6.00003: Predictions of radiative shock experiments on the Omega Laser Carolyn Kuranz, R.P. Drake, J.P. Holloway, D. Bingham, J. Goh, M.J. Grosskopf, M. Trantham, S.R. Klein Radiative shocks, which are exist 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] |
Wednesday, October 29, 2014 10:06AM - 10:18AM |
NO6.00004: Diagnosing Turbulent Shear in HED Experiments on NIF K.A. Flippo, J.L. Kline, F.W. Doss, T.S. Perry, B. Devolder, T.J. Murphy, E.C. Merritt, I.A. Tregillis, E.N. Loomis, D. Schmidt, D. Capelli, S.P. Regan, M.A. Barrios, C.M. Huntington, S.A. MacLaren We report on experiments planned for and performed at the NIF to investigate turbulent mix in and HED r\'{e}gime using a platform scaled from the Omega laser facility. We are investigating turbulence-driven mix from the shear induced Kelvin-Helmholtz instability, like those experienced in an ICF capsule with instabilities present. Two shocks are generated at either end of cylinder, inside CH foams act as a light fluid and the evolution of an Al tracer layer heavy fluid in the center plane is observed using the Big Area Backlighter (BABL), an especially large area backlighter developed for this project. Simulations of the BABL were carried out to optimize spatial profile. Another backlighter, the Long Duration Backlighter (LDBL) a variation of the BABL has also been developed and shot on NIF. The LDBL has been tuned spatially and temporally to emit x-rays in a very flat profile over a 7 ns time frame. Comparison of this data with simulations using the Besnard-Harlow-Rauenzahn (BHR) model is used. BHR is intended for turbulent transport in fluids with large density variations and has the ability to improve our predictive capability of mix in ICF experiments. [Preview Abstract] |
Wednesday, October 29, 2014 10:18AM - 10:30AM |
NO6.00005: Examining the evolution towards turbulence through spatio-temporal analysis of multi-dimensional structures formed by instability growth along a shear layer Elizabeth Merritt, Forrest Doss, Eric Loomis, Kirk Flippo, Barbara Devolder, Leslie Welser-Sherrill, James Fincke, John Kline The counter-propagating shear campaign is examining instability growth and its transition to turbulence relevant to mix in ICF capsules. Experimental platforms on both OMEGA and NIF use anti-symmetric flows about a shear interface to examine isolated Kelvin-Helmholtz instability growth. Measurements of interface (an Al or Ti tracer layer) dynamics are used to benchmark the LANL RAGE hydrocode with BHR turbulence model. The tracer layer does not expand uniformly, but breaks up into multi-dimensional structures that are initially quasi-2D due to the target geometry. We are developing techniques to analyze the multi-D structure growth along the tracer surface with a focus on characterizing the time-dependent structures' spectrum of scales in order to appraise a transition to turbulence in the system and potentially provide tighter constraints on initialization schemes for the BHR model. To this end, we use a wavelet based analysis to diagnose single-time radiographs of the tracer layer surface (w/ low and amplified roughness for random noise seeding) with observed spatially non-repetitive features, in order to identify spatial and temporal trends in radiographs taken at different times across several experimental shots. [Preview Abstract] |
Wednesday, October 29, 2014 10:30AM - 10:42AM |
NO6.00006: Release and recompression measurements of multiple component reservoirs for strength drive experiments on the NIF S.T. Prisbrey, H.-S. Park, C.E. Wehrenberg, C.M. Huntington, B. Maddox, R. Benedetti, P. Graham, T. Baumann, M. Wilson, R. Rudd, A. Arsenlis, B.A. Remington The ability to infer strength in materials driven with staged shocks requires the development and accurate measurement of a multiple-shock drive. We have developed such a drive for use in Ta strength experiments up to $\sim$ 5 Mbar [1], which utilizes an initial shock which is large enough to theoretically generate dislocations within the Ta itself. Our desire to investigate other materials, which melt at a lower pressure on their principle Hugoniot, along with the desire to have a drive with an initial shock below the homogeneous nucleation threshold of $\sim$ 660 kbar [2] has prompted us to design and develop a different $\sim$ 5 Mbar drive with a different initial shock. We report here on the proposed design and experimental results achieved at the National Ignition Facility of several of the new components of the drive -- specifically the lower density foam layer, an iodinated plastic layer, and an aluminum layer. \\[4pt] [1] PoP \textbf{19}, 056311 (2012).\\[0pt] [2] AIP Conf. Proceedings \textbf{1426}, 1379 (2012). [Preview Abstract] |
Wednesday, October 29, 2014 10:42AM - 10:54AM |
NO6.00007: Developing a 3-shock, low-adiabat drive for high pressure material science experiments on NIF Christopher Wehrenberg, Shon Prisbrey, Peter Graham, Hye-Sook Park, Channing Huntington, Brian Maddox, Robin Benedetti, Robert Rudd, Tom Arsenlis, Bruce Remington We describe a series of experiments for basic materials science on NIF to develop a planar, 3-shock, low-adiabat drive to reach peak pressures of 5 Mbar, while keeping the physics samples well below their melt temperatures. The primary diagnostic is VISAR, which measures the compression waves as they travel through a Ta witness plate. X-ray ablation from an indirect drive launches a strong (\textgreater 10 Mbar) shock through a precision fabricated ``reservoir,'' consisting of a CH ablator, followed by layers of Al, CH(18.75{\%}I), 350 mg/cc CRF foam, and a final layer of 10-30 mg/cc foam. This reservoir releases as plasma across a 1.5 mm vacuum gap, then stagnates on the 15 micron thick Ta witness plate, which is backed by a LiF or quartz window. The lowest density reservoir layer sets the strength of the leading shock, which needs to be controlled to keep the physics samples solid, and to control the dislocation density created by this leading shock. We will describe an extensive series of experiments done on NIF to develop this drive. \\[4pt] [1] S. Prisbrey, PoP 19, 056311 (2012). [Preview Abstract] |
Wednesday, October 29, 2014 10:54AM - 11:06AM |
NO6.00008: Experimental Results of Tantalum Flow Stress at 5 Mbar from NIF Hye-Sook Park, A. Arsenlis, L.R. Benedetti, R. Cavallo, C.M. Huntington, B.R. Maddox, J.M. McNaney, S. Prisbrey, R.E. Rudd, S.V. Weber, C.E. Wehrenberg, B.A. Remington We present our first experimental results from the NIF laser to test Ta strength models at high pressures ($\sim$ 5 Mbar), high strain rates ($\sim$ 10$^{7}$ s$^{-1})$ and high strains (\textgreater 30{\%}). We use 800 kJ of laser energy to create a ramped drive via a 4-layer reservoir - gap configuration. The target package includes sinusoidal Ta surface ripples that are used to infer the plastic flow stress of the sample from a measurement of the Rayleigh-Taylor instability ripple growth. The inferred flow stress is approximately twice greater than predictions by the multiscale strength model. It is conjectured that homogeneous nucleation behind the leading shock at $\sim$ 1 Mbar promptly generates a very high dislocation density, thus increasing the strength through the work hardening term. It was also observed that larger initial amplitude ripples grow more than smaller initial amplitude ripples at the same wavelength, suggesting the so-called Drucker effect for solid-state flow due to the Rayleigh-Taylor instability [D. C. Drucker, Mechanics Today, 5, 36 (1980)]. [Preview Abstract] |
Wednesday, October 29, 2014 11:06AM - 11:18AM |
NO6.00009: Laser Shock-Induced Spalling in Tantalum Tane Remington, Christopher Wehrenberg, Brian Maddox, Bruce Remington, Marc Meyers The process of dynamic failure by spalling was established in nano, poly, and mono crystalline tantalum in recovery experiments following laser compression and release. Samples were compressed over a range of pressures between 5-13 GPa. The waves were allowed to reflect at the back surface (specimen thickness ranged from 50-250 $\mu$m) and the process of separation was characterized by SEM. Spall strength was measured by the shock breakout and pull back signal using VISAR. The spall strength increases with increasing strain rate and grain size. In the nano and polycrystals, spalling occurred by ductile fracture favoring grain boundaries. In the monocrystals, the process was of ductile failure by void initiation, growth and coalescence. Work performed at the Jupiter Laser Facility (JLF), Lawrence Livermore National Laboratory (LLNL). This research is funded by the UC Research Laboratories Grant (09-LR-06-118456-MEYM) and the National Laser Users Facility (NLUF) Grant (PE-FG52-09NA-29043). [Preview Abstract] |
Wednesday, October 29, 2014 11:18AM - 11:30AM |
NO6.00010: Experimental observation of Rayleigh-Taylor growth as a function of wavelength in the warm dense matter regime C.M. Huntington, A. Arsenlis, B.R. Maddox, H.-S. Park, S.T. Prisbrey, S.V. Weber, C.E. Wehrenberg, B.A. Remington ``Classical'' Rayleigh-Taylor (RT) growth is characterized by a growth rate $\gamma=\sqrt{k g A_n }$, where $k$ is the wavelength of the unstable mode, $g$ is the acceleration, and the Atwood $A_n$ number characterizes the magnitude of the density jump at the interface. Here we present the results of a set of experiments using face-on x-ray radiography to measure RT growth in a plastic rippled sample. Acceleration of the sample is provided by the stagnation of a releasing shocked plastic ``reservoir,'' which is directly driven by approximately 1 kJ of laser energy at the OMEGA facility. The growth of pre-imposed ripples is recorded using transmission x-ray radiography of a vanadium He$_\alpha$ source, where the opacity of the sample is calibrated to the ripple amplitude. We report the results of experiments at 30 $\mu$m and 60 $\mu$m initial wavelengths, and compare the data to 2D hydrodynamic simulations. [Preview Abstract] |
Wednesday, October 29, 2014 11:30AM - 11:42AM |
NO6.00011: Numerical study of shock-driven cavity collapse using the front tracking method Brett Tully, Nicholas Hawker, Matthew Betney, Yiannis Ventikos The front tracking method, including a tabular equation of state framework, has been previously used by the authors to numerically study the conditions generated during shock-driven cavity collapse. The dominant dynamics involve the formation of a high-speed transverse jet and the subsequent impact of this jet on the leeward bubble wall. The process of jet formation can be interpreted via the same driving mechanism as Richtmyer-Meshkov instability; the reflection of the shockwave causes a focusing of the flow. During impact a small amount of the gas in the cavity is trapped against the leeward wall and is strongly compressed and heated. This jet impact also produces a strong point source shockwave which propagates outwards, further collapsing the now toroidal cavity. The termination of the collapse of the torus corresponds to minimum volume. There are thus two key moments during the collapse where the cavity contents form an inertially confined plasma: first jet impact and second toroidal minimum volume. The present paper elucidates these dynamics with numerical simulations and demonstrates a preliminary comparison to experiments. Basic metrics such as the first phase collapse time are compared, with good agreement. [Preview Abstract] |
Wednesday, October 29, 2014 11:42AM - 11:54AM |
NO6.00012: Experimental study of shock-driven cavity collapse with a single-stage gas gun driver Phillip Anderson, Matthew Betney, Hugo Doyle, Nicholas Hawker, Ronald Roy This paper explores experimental studies of shock-driven cavity collapse using a single-stage gas gun. Shocks of up to 1 GPa are generated in a hydrogel with the impact of a planar-faced projectile (50 mm dia.). Within the hydrogel, a pre-formed cavity (5 mm dia.) is cast, which is collapsed by the interaction with the shockwave. The basic collapse process involves the formation of a high-speed transverse jet and then a second collapse phase driven from jet impact. Single-shot multi-frame schlieren imaging is used to show the position and timing of optical emission in relation to the collapse hydrodynamics. Further, temporally and spectrally-resolved measurements of the optical emission are made through simultaneous use of multiple band-passed PMTs and an integrating spectrometer. This reveals three distinct pulses of emission possessing different frequency content. The first corresponds to the trapping of gas during jet impact; the second and third correspond to the further inertial collapse of the now toroidal cavity. Plasma models are used to provide the first indication of the temperature of these inertially confined plasmas. [Preview Abstract] |
Wednesday, October 29, 2014 11:54AM - 12:06PM |
NO6.00013: Experimental and numerical study of shock-driven collapse of multiple cavity arrays Matthew Betney, Phillip Anderson, Brett Tully, Hugo Doyle, Nicholas Hawker, Yiannis Ventikos This study presents a numerical and experimental investigation of the interaction of a single shock wave with multiple air-filled spherical cavities. The 5 mm diameter cavities are cast in a hydrogel, and collapsed by a shock wave generated by the impact of a projectile fired from a single-stage light-gas gun. Incident shock pressures of up to 1 GPa have been measured, and the results compared to simulations conducted using a front-tracking approach. The authors have previously studied the collapse dynamics of a single cavity. An important process is the formation of a high-speed transverse jet, which impacts the leeward cavity wall and produces a shockwave. The speed of this shock has been measured using schlieren imaging, and the density has been measured with a fibre optic probe. This confirmed the computational prediction that the produced shock is of a higher pressure than the original incident shock. When employing multiple cavity arrays, the strong shock produced by the collapse of one cavity can substantially affect the collapse of further cavities. With control over cavity placement, these effects may be utilised to intensify collapse. This intensification is experimentally measured via analysis of the optical emission. [Preview Abstract] |
Wednesday, October 29, 2014 12:06PM - 12:18PM |
NO6.00014: Direct Shock-Timing Measurements in CH Using Streaked X-Ray Radiography P.M. Nilson, M. Lafon, C.R. Stillman, C. Mileham, R. Boni, T.R. Boehly, D.H. Froula, D.D. Meyerhofer One-dimensional streaked x-ray radiography is used to measure shock coalescence in multishocked plastic. A two-shock system was generated using a ramped drive on the OMEGA EP Laser System. The data show the first shock wave propagating into solid material, followed 2 ns later by the second shock wave. The measured shock trajectories were used to track the system dynamics and determine the shock-coalescence times for different initial shock strengths. The measured shock timings are compared to radiation--hydrodynamic model predictions. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944. [Preview Abstract] |
Wednesday, October 29, 2014 12:18PM - 12:30PM |
NO6.00015: Use of Laser-Generated Ion Beams for Isochoric Heating to Study Plasma-Phase Mix at Heterogeneous Interfaces B.J. Albright, J.C. Fern\'andez, W. Bang, P.A. Bradley, D.C. Gautier, C.E. Hamilton, C.-K. Huang, S. Palaniyappan, M.A. Santiago Cordoba, E. Vold, L. Yin, G. Dwyer, B.M. Hegelich, R. Roycroft The evolution and mixing of high-Z/low-Z plasma interfaces in high energy density plasmas is a problem of profound importance to understanding plasma-phase mix in settings of thermonuclear burn. Recent experiments at the LANL Trident laser facility have used laser-generated aluminum ion beams created under conditions of relativistic induced transparency to heat solid-density, multi-material targets isochorically to temperatures of several eV and observations have been made of the subsequent evolution of the plasma media. Experiments such as these present a new path for the controlled preparation and study of high energy density physics and warm dense matter. This presentation will discuss recent results from these experiments, including supporting radiation-hydrodynamics and kinetic simulations and theory. [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