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 PO8: HED Opacity and Magnetized Plasmas |
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Chair: Bhuvana Srinivasan, Virginia Tech University Room: 212 CD |
Wednesday, November 2, 2016 2:00PM - 2:12PM |
PO8.00001: Opacity Experiments At The National Ignition Facility (NIF) T.S. Perry, J.L. Kline, K.A. Flippo, M.E. Sherrill, E.S. Dodd, B.G. DeVolder, T.J. Urbatsch, R.F Heeter, M.B. Schneider, D.A. Liedahl, B.G. Wilson, C.A. Iglesias, Y.P. Opachich, P.W. Ross, J.E. Bailey, G.A. Rochau X-ray opacities are essential to the radiation-hydrodynamic simulations used to model astrophysical systems or inertial confinement fusion experiments. Recent opacity experiments have shown up to a factor of two discrepancy between theory and experiment. To address this issue a new experimental opacity platform is being developed on the NIF to crosscheck the recent results. The first experiments, starting in 2017, will begin by measuring the opacity of iron at a temperature of \textasciitilde 160 eV and an electron density of \textasciitilde 7x10$^{\mathrm{21}}$ cm$^{\mathrm{-3}}$. This and several following presentations will describe this effort. [Preview Abstract] |
Wednesday, November 2, 2016 2:12PM - 2:24PM |
PO8.00002: Design of Initial Opacity Platform at the National Ignition Facility R.F. Heeter, M.F. Ahmed, S.L. Ayers, J.A. Emig, C.A. Iglesias, D.A. Liedahl, M.B. Schneider, B.G. Wilson, E.J. Huffman, J.A. King, Y.P. Opachich, P.W. Ross, J.E. Bailey, G.A. Rochau, R.S. Craxton, E.M. Garcia, P.W. McKenty, R. Zhang, T. Cardenas, B.G. DeVolder, E.S. Dodd, J.L. Kline, M.E. Sherrill, T.S. Perry The absorption and re-emission of x-rays by partly stripped ions plays a critical role in stars and in many laboratory plasmas. A NIF Opacity Platform has been designed to resolve a persistent disagreement between theory and experiments on the Sandia Z facility, studying iron in conditions closely related to the solar radiation-convection transition boundary. A laser heated hohlraum ``oven'' will produce iron plasmas at temperatures \textgreater 150 eV and electron densities $\ge $7x10$^{\mathrm{21}}$/cm$^{\mathrm{3}}$, and be probed with continuum X-rays from a capsule implosion backlighter source. The resulting X-ray transmission spectra will be recorded on a specially designed Opacity Spectrometer. [Preview Abstract] |
Wednesday, November 2, 2016 2:24PM - 2:36PM |
PO8.00003: Iron Opacity Platform Performance Characterization at the National Ignition Facility Y.P. Opachich, P.W. Ross, R. F. Heeter, M. A. Barrios, D. A. Liedahl, M.J. May, M.B. Schneider, R.S. Craxton, E.M. Garcia, P.W. McKenty, R. Zhang, J.L. Weaver, K.A. Flippo, J.L. Kline, T.S. Perry A high temperature opacity platform has been fielded at the National Ignition Facility (NIF). The platform will be used to study opacity in iron at a temperature of \textasciitilde 160 eV. The platform uses a \textasciitilde 6 mm diameter hohlraum driven by 128 laser beams with 530 kJ of energy in a \textasciitilde 3 ns pulse to heat an iron sample. Absorption spectra of the heated sample are generated with a broadband pulsed X-ray backlighter produced by imploding a vacuum-filled CH shell. The shell is 2~mm in diameter and \textasciitilde 20 microns thick, driven by 64 beams with 250 kJ in a 2.5 ns pulse. The hohlraum and backlighter performance have both been investigated recently and will be discussed in this presentation. * This work was performed by National Security Technologies, LLC, under Contract No. DE-AC52-06NA25946 with the U.S. Department of Energy. DOE/NV/25946--2892. [Preview Abstract] |
Wednesday, November 2, 2016 2:36PM - 2:48PM |
PO8.00004: Design And First Use of the NIF Opacity Spectrometer J.A. King, P.W. Ross, E.J. Huffman, Y.P. Opachich, R.F. Heeter, M. Ahmed, D.A. Liedahl, M.B. Schneider, E. Dodd, K.A. Flippo, J.L. Kline, F.E. Lopez, T.N. Archuleta, T.S. Perry Recent experiments at the Sandia Z facility have raised questions about models used in calculating L-shell opacities of mid-Z elements. A platform is being developed to check these results at the National Ignition Facility (NIF). The NIF experiments require a new X-ray opacity spectrometer (OpSpec) for the iron L-shell X-ray band, spanning photon energies from 540 eV -- 2100 eV with a resolving power E/$\Delta $E \textgreater 700. The design of the OpSpec and photometric calculations based on expected opacity data are also presented. First use on NIF is expected in September 2016. [Preview Abstract] |
Wednesday, November 2, 2016 2:48PM - 3:00PM |
PO8.00005: Systematic measurements of opacity dependence on temperature, density, and atomic number at stellar interior conditions. James Bailey, T. Nagayama, G.P. Loisel, G.A. Rochau, C. Blancard, J. Colgan, Ph. Cosse, G. Faussurier, C.J. Fontes, I. Golovkin, S.B. Hansen, C.A. Iglesias, D.P. Kilcrease, J.J. MacFarlane, R.C. Mancini, S.N. Nahar, C. Orban, A.K. Pradhan, M. Sherrill, B.G. Wilson, J.C. Pain, F. Gilleron Model predictions for iron opacity are notably different from measurements performed at conditions similar to the boundary between the solar radiation and convection zone [J.E. Bailey et al., \textit{Nature} \textbf{517}, 56 (2015)]. New measurements at the Sandia Z facility with chromium, iron, and nickel are providing a systematic study of how opacity changes with temperature, density, and atomic number. These measurements help further evaluate possibilities for experiment errors and help constrain hypotheses for opacity model refinements. $++$Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000. [Preview Abstract] |
Wednesday, November 2, 2016 3:00PM - 3:12PM |
PO8.00006: Observation of subsonic and supersonic radiation fronts on OMEGA utilizing radiation transport through Sc-doped aerogels H. M. Johns, J Kline, N Lanier, T Perry, C Fontes, C Fryer, C Brown, J Morton, J Hager The propagation of a heat front in an astrophysical or inertial confinement fusion plasma involves both the equation of state and the opacity of the plasma, and is therefore an important and challenging radiation transport problem. Past experiments have used absorption spectroscopy in chlorinated foams to measure the heat front. (D. Hoarty \textit{et al} PRL \textbf{82}, 3070, 1999). Recent development of Ti-doped cylindrical aerogel foam targets (J. Hager et al submitted to RSI) results in a more suitable platform for higher temperatures on NIF than Cl dopant. Ti K-shell absorption spectra can be modeled with PrismSPECT to obtain spatially resolved temperature profiles between 100-180eV. Sc dopant has been selected to characterize the heat front between 60-100eV. Improved understanding of non-planckian x-ray drives generated by hohlraums will advance characterization of the radiation transport. Prior work demonstrates PrismSPECT with OPLIB is more physically complete for Sc (H. Johns et al submitted to RSI). We will present the first application of spectroscopic analysis of the Sc-doped aerogels utilizing this method. [Preview Abstract] |
Wednesday, November 2, 2016 3:12PM - 3:24PM |
PO8.00007: Design Parameter Studies of Emission-Based Iron Opacity Measurements Madison E. Martin, Richard A. London, Sedat Goluoglu, Heather D. Whitley Opacity is a critical parameter in the transport of radiation in systems such as inertial confinement fusion capsules and stars. The resolution of current disagreements between solar models and helioseismological observations would benefit from experimental validation of theoretical opacity models. Short pulse lasers can be used to heat targets to higher temperatures and densities than long pulse lasers and pulsed power machines, thus potentially enabling access to x-ray emission spectra at conditions relevant to solar models. The radiation-hydrodynamic code HYDRA[1] is used to investigate the effects of modifying laser energy, laser pulse length, and target dimensions on the plasma conditions, x-ray emission, and inferred opacity of a buried layer iron target. The accuracy of the opacity inference is sensitive to tamper emission and optical depth effects. An example design that reaches temperatures and densities relevant to the radiative zone of the sun while reducing optical depth and tamper emission effects will be discussed. [1] M. M. Marinak, et. al. Physics of Plasmas 8, 2275 (2001). [Preview Abstract] |
Wednesday, November 2, 2016 3:24PM - 3:36PM |
PO8.00008: Demonstration of combined radiography and x-ray scattering measurements of shocked foam Patrick Belancourt, Wolfgang Theobald, Paul Keiter, Timothy Collins, Mark Bonino, Sean Regan, Pawel Kozlowski, Paul Drake High-energy-density physics experiments often use foams due to their low, tunable densities and being machinable. Simulating these experiments can be difficult due to the equation of state being largely unknown for shocked foams. This talk will focus on an experiments dedicated to measuring the temperature, ionization and density of shocked foams from simultaneous x-ray Thomson scattering and radiography measurements. The foam used in this experiment is carbonized resorcinol formaldehyde foam with an initial density of 0.1 g/cc. One OMEGA EP beam drives a shock into the foam, while the remaining three beams irradiate a nickel foil coated with titanium to create the x-ray backlighter.. The primary diagnostic for this platform, the imaging x-ray Thomson spectrometer (IXTS), spectrally resolves the scattered x-ray beam while imaging in one spatial dimension. The IXTS is ideally suited to measure plasma conditions upstream, downstream and at the shock front in the foam. Preliminary results from this experiment will be shown. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944, the University of Rochester, and the New York State Energy Research and Development Authority. [Preview Abstract] |
Wednesday, November 2, 2016 3:36PM - 3:48PM |
PO8.00009: Formation of a bifurcated current layer by the collision of supersonic magnetized plasmas Lee Suttle, Jack Hare, Sergey Lebedev, Andrea Ciardi, Nuno Loureiro, Guy Burdiak, Jerry Chittenden, Thomas Clayson, Jiming Ma, Nicolas Niasse, Timothy Robinson, Roland Smith, Nicolas Stuart, Francisco Suzuki-Vidal We present detailed experimental data showing the formation and structure of a current layer produced by the collision of two supersonic and well magnetized plasma flows. The pulsed-power driven setup provides two steady and continuous flows, whose embedded magnetic fields mutually annihilate inside the interaction region giving rise to the current layer. Spatially resolved measurements with Faraday rotation polarimetry, Thomson scattering and laser interferometry diagnostics show the detailed distribution of the magnetic field and other plasma parameters throughout the system. We show that the pile-up of magnetic field ahead of the annihilation gives rise to the multi-layered / bi-directional nature of the current sheet, and we discuss pressure balance and energy exchange mechanisms within the system. [Preview Abstract] |
Wednesday, November 2, 2016 3:48PM - 4:00PM |
PO8.00010: Precision Mapping of Laser-Driven Magnetic Fields and Their Evolution in High-Energy-Density Plasmas* Lan Gao, P. Nilson, I. Igumenshchev, M. G. Haines, D. H. Froula, R. Betti, D. D. Meyerhofer The magnetic fields generated at the surface of a laser-irradiated planar solid target are mapped using ultrafast proton radiography. Thick (50 $\mu $m) plastic foils are irradiated with 4-kJ, 2.5-ns laser pulses focused to an intensity of 4 x 10$^{\mathrm{14}}$ W/cm$^{\mathrm{2}}$. The data show magnetic fields concentrated at the edge of the laser-focal region, well within the expanding coronal plasma. The magnetic-field spatial distribution is tracked and shows good agreement with 2D resistive magnetohydrodynamic simulations using the code DRACO when the Biermann battery source, fluid and Nernst advection, resistive magnetic diffusion, and Righi-Leduc heat flow are included. The work provides significant insight into the generation and transport of Biermann fields in laser-produced plasmas, particularly those used in laser-driven magnetic reconnection and laboratory astrophysics experiments. *L. Gao \textit{et al}., Phy. Rev. Lett. 114, 215003 (2015) [Preview Abstract] |
Wednesday, November 2, 2016 4:00PM - 4:12PM |
PO8.00011: Interaction of laser radiation with plasma under the MG external magnetic field V. V. Ivanov, A. V. Maximov, R. Betti, H. Sawada, Y. Sentoku Strong magnetic fields play an important role in many physical processes relevant to astrophysical events and fusion research. Laser produced plasma in the MG external magnetic field was studied at the 1 MA pulsed power generator coupled with the laser operated in ns and ps regimes. Rod loads and coils under 1 MA current were used to produce a magnetic field of 2-3 MG. In one type of experiments, a 0.8 ns laser pulse was focused on the load surface with intensity of 3x10$^{\mathrm{15}}$ W/cm$^{\mathrm{2}}$. Laser diagnostics showed that the laser produced plasma expands in the transversal magnetic field and forms a thin plasma disc with a typical diameter of 3-7 mm and thickness of 0.2-0.4 mm. A magnetosonic-type wave was observed in the plasma disc and on the surface of the rod load. The plasma disc expands radially across the magnetic field with a velocity of the order of the magnetosonic velocity. Physical mechanisms involved in the formation of the plasma disc may be relevant to the generation of plasma loops in sun flares. Other experiments, with a 0.4 ps laser pulse were carried for investigation of the isochoric heating of plasma with fast electrons confined by the strong magnetic field. The laser beam was focused by the parabola mirror on a solid target in the magnetic field of the coil. [Preview Abstract] |
Wednesday, November 2, 2016 4:12PM - 4:24PM |
PO8.00012: On the magnetized disruption of inertially-confined plasma flows Mario Manuel, Carolyn Kuranz, Alexander Rasmus, Sallee Klein, Michael MacDonald, Matt Trantham, Jeff Fein, Patrick Belancourt, Rachel Young, Paul Keiter, R Paul Drake, Brad Pollock, Jaebum Park, Andrew Hazi, Jackson Williams, Hui Chen The creation and disruption of inertially-collimated plasma flows is investigated through experiment, simulation, and analytical modeling. Laser-generated plasma-jets are shown to be disrupted by an applied 5T B-field along the jet axis. An analytical model of the system describes the disruption mechanism through the competing effects of B-field advection and diffusion. These results indicate that for $Re_m\sim$10-100, the ratio of inertial to magnetic pressures plays an important role in determining whether a jet is formed, but at high enough $Re_m$, axial B-field amplification prevents inertial collimation altogether. This work is funded by the U.S. DOE, through the NNSA-DS and SC-OFES Joint Program in HED Laboratory Plasmas, grant number DE-NA0001840 and in collaboration with LLNL under contract DE-AC52-07NA27344. Support for this work was provided by NASA, under contract NAS8-03060, through Einstein Postdoctoral Fellowship grant number PF3-140111. Software used in this work was developed in part by the DOE NNSA ASC- and DOE Office of Science ASCR-supported Flash Center. [Preview Abstract] |
Wednesday, November 2, 2016 4:24PM - 4:36PM |
PO8.00013: Magnetised bow shocks and oblique shock interactions: HEDLA experiments on the Magpie pulsed-power facility G.C. Burdiak, S.V. Lebedev, J.P. Chittenden, T. Clayson, C. Garcia, J.D. Hare, N. Niasse, L.G. Suttle, F. Suzuki-Vidal, A. Frank, A. Ciardi We present results from magnetised shock experiments performed on the Magpie ($\sim $1 MA, 250 ns) pulsed-power facility. Shocks are formed around cylindrical and oblique planar obstacles positioned in a supersonic, super-Alfvenic plasma flow (M$_{\mathrm{S}}=$5, M$_{\mathrm{A}}=$2.5, v$_{\mathrm{f}}=$70 km/s). The plasma flow is produced by an inverse, exploding wire array z-pinch and carries an embedded magnetic field that is well frozen in (Re$_{\mathrm{M}} \quad =$ 20). We show how the structure of bow and oblique shocks is dramatically affected by the orientation of the advected magnetic field with respect to the obstacles. More complex obstacle geometries allow us to study the interaction of multiple magnetised oblique shocks. These systems can cause the annihilation of magnetic flux and the generation of shear flow along a slip layer. [Preview Abstract] |
Wednesday, November 2, 2016 4:36PM - 4:48PM |
PO8.00014: Magnetohydrodynamics of high-energy-density-plasma in strong magnetic field Kazuki matsuo, Hideo Nagatomo, Takayoshi Sano, Zhe Zhang, Youichi Sakawa, Yukiko Hara, Hiroshi Shimogawara, Yasunobu Airikawa, Shouhei Sakata, KingFaiFarley Law, SeungHo Lee, Sadaoki Kojima, Hiroki Katou, Keisuke Shigemori, Shinsuke Fujioka, Hiroshi Azechi The magneto-hydrodynamics (MHD) of a high-energy-density-plasma (HEDP) in a strong external magnetic field contains a lot of fundamental and essential physics related to astro- and solar- physics and B-assisted inertial confinement fusion energy development. Especially, hydrodynamic instability in a strong magnetic field is a key physics for success of B-assisted inertial confinement fusion. Hydrodynamic instability growth is affected by strong magnetic field as a result of non-uniform heat flow. Experiments were conducted with a corrugated plastic target that is set between a pair of capacitor-coil. A pair of capacitor-coil targets was used to generate spatially uniform magnetic field. The plastic targets were irradiated by an intense laser pulse having 10$^{\mathrm{13}}$ W/cm$^{\mathrm{2}}$ of intensity. Temporal evolution of perturbation growth was observed with x-ray backlight technique. Enhancement of the perturbation growth in strong magnetic field was observed experimentally, and the result was consistent with hydrodynamic simulation. [Preview Abstract] |
Wednesday, November 2, 2016 4:48PM - 5:00PM |
PO8.00015: ABSTRACT WITHDRAWN |
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