Bulletin of the American Physical Society
53rd Annual Meeting of the APS Division of Plasma Physics
Volume 56, Number 16
Monday–Friday, November 14–18, 2011; Salt Lake City, Utah
Session JO8: ICF Diagnostics: X-ray |
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Chair: Joe Kilkenny, Lawrence Livermore National Laboratory Room: Ballroom I |
Tuesday, November 15, 2011 2:00PM - 2:12PM |
JO8.00001: Time-Resolved Polar X-Ray Images of Capsule Implosions on the NIF Steven Glenn, Nobuhiko Izumi, George Kyrala, David Bradley, Richard Town, Jose Milovich, Steve Weber, Robin Benedetti Key experiments leading to ignition at the National Ignition Facility (NIF) involve measuring the symmetry of imploding capsules using images recorded by x-ray framing cameras. Recent polar x-ray images display a wide variety of interesting features including four-fold azimuthal symmetry. We describe techniques that have been developed to quantify the azimuthal shape and explain the physical phenomena associated with features observed in the images. [Preview Abstract] |
Tuesday, November 15, 2011 2:12PM - 2:24PM |
JO8.00002: Symmetry tuning from analyzing the shape of x-ray self emission of Megajoule implosions at NIF G. Kyrala, J. Kline, S. Glenn, D. Bradley, R. Benedetti, N. Izumi, T. Mah, S. Dixit, S. Glenzer, N. Meezan, S. Weber, L. Suter, R. Town, D. Callahan, J. Ralph, T. Doppner, O. Landen X-ray self-emission from imploding capsules driven by hohlraum radiation has been used to tune the symmetry of symcaps in the past. However as capsules have changed, new features have appeared in the x-ray images that have led us to re-examine the analysis and helped us tune the symmetry of different imploding cryogenically layered capsules as well. We had observed jets in the implosion and we tried identifying those jets, and avoid their effect on the observed time dependent symmetry. Since, we have tried to quantify the effect of these jets on the measured symmetry, x-ray history, and x-ray emission bang time. In this presentation we will show the effect of including the emission form the jets, show a correlation between the observations from different directions, give an estimate of the velocity of these features, as well as give a time history of their emission and size. We will also show how the time history have changed for the different laser conditions for the cryogenically layered targets, the implosion size was smaller than that for symcaps, and consequently the compression was larger. [Preview Abstract] |
Tuesday, November 15, 2011 2:24PM - 2:36PM |
JO8.00003: Spectrally Resolved Imaging of X-Ray Self Emission from NIF Implosions T. Ma, N. Izumi, D.K. Bradley, C.J. Cerjan, S. Dixit, O.L. Landen, A.J. Mackinnon, N.B. Meezan, R.R. Prasad, P.T. Springer, R.P.J. Town, S.V. Weber, S.H. Glenzer, J.L. Kline, G. Kyrala Accurately assessing and optimizing the implosion performance of inertial confinement fusion capsules is a crucial step to achieving ignition on the NIF. We have applied differential filtering (matched Ross filter pairs) to provide spectrally resolved time-integrated absolute emission images of the imploded core of cryogenic layered targets. By limiting the spectral range of imaging, we can diagnose the hydrodynamic mix of Ge-doped ablator mass within the hot spot, core symmetry without interpenetration mix, shell assembly, and distribution of temperature and hot spot mass. Further, the measured brightness of Ge K-shell emission and bremsstrahlung allows for the inference of burn-weighted electron temperature, hot spot mass, rhoR, density, and pressure. Experimental results and a simple hot spot pressure model will be presented. [Preview Abstract] |
Tuesday, November 15, 2011 2:36PM - 2:48PM |
JO8.00004: Calibration of the temporal response of Gated X-ray Framing Cameras for Imaging on NIF L.R. Benedetti, P. Bell, D.K. Bradley, S. Glenn, R.F. Heeter, J. Holder, N. Izumi, N. Simanovskaia We present methods and results for off-line testing of gated x-ray framing cameras such as the GXDs in use at the National Ignition Facility (NIF). These cameras capture a time dependent sequence of images by sending a voltage pulse across a stripline-coated microchannelplate(mcp). The amplification mechanism of the mcp produces a time-dependent gain that is narrower than the electrical pulse. While the basic operating mechanism is well-understood, the properties of the gain function are difficult to measure. We find that an integrated method can be used to interpret an ensemble of short-pulse laser images to determine optical gate width (relative to the electrical pulse width), pulse velocity and gain loss (droop) across the microchannelplate. We will compare these results to in situ measurements of flat-field and gain droop using the NIF laser. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 (LLNL-ABS-490824) [Preview Abstract] |
Tuesday, November 15, 2011 2:48PM - 3:00PM |
JO8.00005: X-Ray Imaging at High Neutron Yields David Bradley X-ray imaging is an important and established diagnostic tool for ICF implosion experiments. The National Ignition will soon be producing radiation environments and neutron yields that will be higher than any produced in laboratory settings in the past. Even for a non-igniting plasma (1017 neutrons) an unshielded diagnostic situated outside the target chamber, but inside the target bay will be subjected to a neutron fluence in excess of 1010 /cm2, with a comparable gamma fluence. These conditions are sufficient to cause unacceptable backgrounds or permanent damage to detectors. We will present modeling, experimental data, and design concepts for x-ray imaging with increasing neutron yield. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. [Preview Abstract] |
Tuesday, November 15, 2011 3:00PM - 3:12PM |
JO8.00006: Temporally Resolved Measurement of X-ray Radiation using DIXI, a Pulse-dilation Enhanced Gated Framing Camera S.R. Nagel, P.M. Bell, D.K. Bradley, M.A. Barrios, J. Emig, J.R. Hunter, G.W. Collins, T.J. Hilsabeck, J.D. Kilkenny, T. Chung, B. Sammuli, J.D. Hares, A.K.L. Dymoke-Bradshaw We present the first time resolved x-ray measurements from DIXI, a new diagnostic instrument which will be fielded at the NIF in the next year. DIXI utilizes pulse-dilation technology [1] to achieve x-ray imaging with temporal gate times below 10 ps. Performance characterization measurements using x-ray illumination were conducted using the COMET laser facility at the Lawrence Livermore National Laboratory. Results from these short pulse laser driven plasma experiments are given along with comparisons to other x-ray diagnostic instruments. Lawrence Livermore National Laboratory is operated by Lawrence Livermore National Security, LLC, for the U.S. Department of Energy, National Nuclear Security Administration under Contract DE-AC52-07NA27344. Work supported by U.S. Department of Energy under Contract DE-AC52-06NA27279. LLNL-ABS-490815. \\[4pt] [1] T. J. Hilsabeck et. al., Rev. Sci. Instrum., 81, 10E317, (2010) [Preview Abstract] |
Tuesday, November 15, 2011 3:12PM - 3:24PM |
JO8.00007: ABSTRACT WITHDRAWN |
Tuesday, November 15, 2011 3:24PM - 3:36PM |
JO8.00008: An Ultrafast X-ray Diagnostic Suite for Burning Plasmas Kevin Baker, Richard Stewart, Paul Steele, Steve Vernon, Warren Hsing, Susan Haynes Ignition designs on the National Ignition Facility predict $\sim$ 10$^{19}$ neutrons in a time of 15 -- 20 ps. The very short burn time and small size of the burning plasma will require x-ray diagnostics with time resolutions of a few ps and high spatial resolution which can function in extremely large neutron fluxes. One promising solution to this challenge is to perform an ultrafast conversion of the x-ray signals into the optical regime, $<$100 fs, and to relay image the signal out of the chamber and into a shielded bunker. A diagnostic suite, Grating Actuated Transient Optical Recorder (GATOR), has been developed which uses the ultrafast near-band-edge change in the optical index of refraction of semiconductors caused by x-ray generated free carriers to achieve this goal. The GATOR diagnostic suite has been tested on a laser-produced x-ray source at the Jupiter Laser Facility and the performance of this diagnostic suite, which includes a multi-temporal frame 2-D imager, a continuous-time 1-D imager and a single channel continuous-time recorder, is presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. [Preview Abstract] |
Tuesday, November 15, 2011 3:36PM - 3:48PM |
JO8.00009: X-ray Thomson Scattering from Spherically Imploded D$^{3}$He filled capsules Andrea Kritcher, Andrew Smith, Tilo Doeppner, Aaron Miles, Otto Landen, Riccardo Tommasini, Warren Hsing, Siegfried Glenzer We plan to measure the Novel time-resolved electron temperature of gas filled spherically imploding capsules-type targets at the Omega OMEGA laser facility, via x ray Thomson scattering. These experiments will aim to characterize the energy balance and the ion and electron temperature equilibration times for plasmas not in local thermodynamic equilibrium (non-LTE). In these experiments, the non-collective, or microscopic particle behavior of the gas, will be probed by scattering a 9 keV Zn He-alpha x-ray source from the gas at angles of 90$^{\circ}$ and 135$^{\circ}$. Then, the width of the scattered Compton feature for these non-degenerate plasmas will provide a direct measure of the electron temperature from first principles due to Doppler broadening. These measurements will be combined with previous platforms to infer the time resolved ion temperature by measuring nuclear reaction products from the D-D and D-$^{3}$He reactions that depend strongly on ion temperature. The measured time resolved ion and electron temperatures will be compared, thus enabling investigation of ion and electron equilibration times in non-LTE plasmas. These experiments will provide an additional platform for studying the electron temperature, using Thomson scattering, of non-LTE imploding gas filled capsules at the National Ignition Facility (NIF). Work performed under the auspices of the USDoE by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-490825 [Preview Abstract] |
Tuesday, November 15, 2011 3:48PM - 4:00PM |
JO8.00010: Probing ionization of proton-heated matter with X-ray Thomson scattering P. Davis, S. LePape, P. Neumayer, D. Hochhaus, T. Ma, T. Doeppner, A.L. Kritcher, C. Fortmann, A. Bennuzzi-Mounaix, A. Ravasio, M. Koenig, T. White, C. Brown, G. Gregori, R. Falcone, O.L. Landen, S.H. Glenzer We have demonstrated for the first time the effect of band structure on ionization state in the warm, dense matter regime. We compare the ionization state of two materials, B and BN, which have different room temperature band gaps. We show that in dense plasma conditions at temperatures of 13-18 eV, the band-gap of BN persists and lowers the ionization state to 0.5, compared to 2.5 in B. The experiment was performed on LLNL's Titan laser. The ultra-intense laser beam was split into two beams: one generated a proton beam while the other created a K-alpha x-ray probe. The proton beam isochorically heated the target foil, creating a solid-density plasma. Forward scattered x-rays were spectrally dispersed, providing an accurate measurement of the ionization and temperature from the position of the plasmon feature and the ratio of up- to down-shifted plasmon signals. *This work was performed under the auspices of the U.S. DOE by the LLNL, through the Institute for Laser Science and Applications, under contract DE-AC52-07NA27344. The authors also acknowledge support from LDRD Grant No. 08-LW-004 and the NNSA SSGF program. [Preview Abstract] |
Tuesday, November 15, 2011 4:00PM - 4:12PM |
JO8.00011: Same-Shot X-Ray Thomson Scattering and Streaked Imaging of Xenon Radiative Shock Experiments Channing Huntington, Eliseo Gamboa, Christine Krauland, Carolyn Kuranz, R. Paul Drake, Siegfried Glenzer We review the experimental design and results from recent CRASH radiative shock experiments at the Omega Laser facility. These experiments seek to measure the system with high accuracy, employing streaked x-ray radiography and x-ray Thomson scattering diagnostics on each shot. We detail how this diagnostic combination allows for precise interrogation of the different regions of the shock, including the radiation-heated upstream precursor, the radiatively collapsed cooling layer, and the downstream material. Spatially and temporally correlated data from the x-ray streak camera and gated spectrometer is shown, and plans for future iterations of radiative shock experiments are also discussed. [Preview Abstract] |
Tuesday, November 15, 2011 4:12PM - 4:24PM |
JO8.00012: On using K-edge filters to enhance resolution of hard x-ray spectroscopy Nino Pereira, Bruce Weber, David Phipps, Joe Schumer, John Seely Near-coincidences of x-ray fluorescence lines of one material with the K-edge of a near-higher atomic number material can sometimes be used to measure small changes in the energy of the line, from an atom's ionization or other effects. We have measured such changes in the K-line radiation from iridium with a lutetium filter, and ytterbium with a thulium filter, using the Plasma- Filled Rod Pinch at the Naval Research Laboratory. This paper discusses these results, and the analysis done to date toward the possible use of such a K-edge filter for NIF hohlraums. [Preview Abstract] |
Tuesday, November 15, 2011 4:24PM - 4:36PM |
JO8.00013: Directly driven, tamped heavy ion ICF targets Matthew Terry, John Perkins, John Barnard Directly driven, tamped heavy ion ICF targets have the potential for high hydrodynamic efficiency while also relaxing accelerator phase space constraints by allowing high kinetic energy ions. The combination of direct heating of the ablator and energy deposition within a high Z tamper leads to a dynamic spectrum of hohlraum-like, x-ray drive and direct drive-like ablation. We discuss the development of a directly driven, tamped, heavy ion ICF target with emphasis on continuum of indirect and direct drive in these targets. Additionally, we discuss the compatibility of shock ignition with this class of targets. [Preview Abstract] |
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