Bulletin of the American Physical Society
57th Annual Meeting of the APS Division of Plasma Physics
Volume 60, Number 19
Monday–Friday, November 16–20, 2015; Savannah, Georgia
Session PO5: Baryonic Mix & Neutron Diagnostics |
Hide Abstracts |
Chair: Leslie Welser Sherrill, Los Alamos National Laboratory Room: 200 |
Wednesday, November 18, 2015 2:00PM - 2:12PM |
PO5.00001: Mechanisms for ion species segregation in the Schunk-Zimmerman multispecies ion-transport model Nelson Hoffman The Schunk-Zimmerman model of multispecies ion transport is based on diffusion in local gradients of concentration, pressure, and temperature [Hoffman \textit{et al}. Phys. Plasmas \textbf{22}, 052707 (2015)]. It represents barodiffusion as well as loss of low-Z ions across a high-Z interface. We demonstrate these phenomena in simple planar simulations of shock waves and low-Z/high-Z interfaces in multicomponent plasmas, and assess the possibility that the model may explain long-standing observations that have been interpreted as evidence for ion species segregation in inertial-fusion capsule implosions [Rygg \textit{et al}. Phys. Plasmas \textbf{13}, 052702 (2006); Herrmann \textit{et al}. Phys. Plasmas \textbf{16}, 056312 (2009); Casey \textit{et al}. PRL \textbf{108}, 075002 (2012); Amendt \textit{et al}. PRL \textbf{105}, 115005 (2010)]. [Preview Abstract] |
Wednesday, November 18, 2015 2:12PM - 2:24PM |
PO5.00002: Non-hydrodynamic mix at the fuel-shell interface in shock-driven ICF implosions H. Sio, H.G. Rinderknecht, C.K. Li, A. Zylstra, M. Gatu Johnson, J.A. Frenje, R.D. Petrasso, P. Amendt, S.C. Wilks, C. Bellei It is well-understood that unmitigated hydrodynamic instability growth at the fuel-shell interface significantly degrades ICF implosion performance. Other ion transport mechanisms due to long mean-free-path effects across an interface, such as diffusion or shock-front transport of ions, are less well-understood. A new non-hydrodynamic mixing mechanism across the fuel-shell interface was explored using thin-CD shell targets filled with 3He gas on OMEGA. Laser conditions were varied to adjust the level of non-hydrodynamic mixing across the CD-3He interface, and nuclear diagnostics were used to measure the reaction histories and spatial profile of the 14.7 MeV D3He-p created from mixing of the D in the shell into the 3He gas. Preliminary results indicate substantial fuel-shell mix prior to the deceleration phase, at a time during which hydrodynamic instability growth is expected to be negligible. Comparison to radiation-hydrodynamic simulations with and without ion diffusion models, as well as expectations from fully kinetics LSP simulations, will be discussed. [Preview Abstract] |
Wednesday, November 18, 2015 2:24PM - 2:36PM |
PO5.00003: Studies of ion species separation in ICF-relevant plasmas at OMEGA Hans Rinderknecht, Scott Wilks, Peter Amendt, Steve Ross, Hye-Sook Park, Maria Gatu Johnson, Johan Frenje, Chikang Li, Fredrick Seguin, Hong Sio, Richard Petrasso, Michael Rosenberg, Chad Forrest, Vladimir Glebov, Christian Stoeckl, Craig Sangster, Alex Zylstra, Nelson Hoffman, Tom Kwan, Olivier Larroche Plasmas produced in high-energy density (HED) and inertial confinement fusion (ICF) experiments generally contain multiple ion species, which allows for multiple-ion species dynamics that are not simulated in typical single-ion fluid hydro codes. In implosions of D$^{\mathrm{3}}$He-gas filled thin-glass spheres on the OMEGA laser facility, comprehensive nuclear diagnostics were used to infer the composition of the fuel during nuclear production, demonstrating that the deuterium fraction was reduced during the implosion of the fuel. Hydrodynamic simulations including an ion diffusion model indicate that pressure, temperature, and potential gradients drive diffusive separation of the ion species, producing better agreement with the experiments than standard hydrodynamic codes. The results of fully kinetic (Vlasov-Fokker-Planck and PIC) simulations confirm the importance of multi-species dynamics to the evolution of these experiments. Implications for multi-species (DT) cryogenic implosions on the National Ignition Facility will be addressed. This work was partially supported by the US DOE, NLUF, LLE, and GA. [Preview Abstract] |
Wednesday, November 18, 2015 2:36PM - 2:48PM |
PO5.00004: X-ray spectroscopic signatures of ion species separation in ICF implosions on OMEGA Peter Hakel, Scott Hsu, Hans Herrmann, Yong Ho Kim, Mark Schmitt, Grigory Kagan, Aaron McEvoy, James Colgan, Christopher Fontes, David Kilcrease, Manolo Sherrill, Rick Rauenzahn This work aims to provide a direct measurement of the species separation through experimental inference of the ion density profiles, and comparisons of the data with simulations that explicitly model multi-ion-species diffusion. We also describe the development of a new code capable of modeling x-ray spectral emission from ICF capsules that accounts for the effects of spatial gradients in species distributions throughout the target. This new code named FESTR also allows the inclusion of NLTE, opacity, and Stark broadening effects on x-ray spectral line emissions. We show preliminary results from an OMEGA campaign to obtain direct measurements of ion species separation via advanced analysis of x-ray spectroscopy and spectrally resolved imaging data. These were symmetric direct-drive implosions of CH capsules with deuterium and trace argon gas fills. The implosions were designed to be in a collisional, diffusive regime and to take advantage of interspecies diffusion between the D and Ar driven by temperature gradients in the hot spot. X-ray spectral line emissions and narrowband images from He-like and H-like Ar ions are used to infer the spatial separation of Ar from D. [Preview Abstract] |
Wednesday, November 18, 2015 2:48PM - 3:00PM |
PO5.00005: Design of a Neutron Temporal Diagnostic for measuring DD or DT burn histories at the NIF B. Lahmann, J.A. Frenje, H. Sio, R.D. Petrasso, D.K. Bradley, S. le Pape, A.J. Mackinnon, N. Isumi, A. Macphee, C. Zayas, B.K. Spears, H. Hermann, T.J. Hilsabeck, J.D. Kilkenny The DD or DT burn history in Inertial Confinement Fusion (ICF) implosions provides essential information about implosion performance and helps to constrain numerical modeling. The capability of measuring this burn history is thus important for the NIF in its pursuit of ignition. Currently, the Gamma Reaction History (GRH) diagnostic is the only system capable of measuring the burn history for DT implosions with yields greater than $\sim$ 1e14. To complement GRH, a new NIF Neutron Temporal Diagnostic (NTD) is being designed for measuring the DD or DT burn history with yields greater than $\sim$ 1e10. A traditional scintillator-based design and a pulse-dilation-based design are being considered. Using MCNPX simulations, both designs have been optimized, validated and contrasted for various types of implosions at the NIF. [Preview Abstract] |
Wednesday, November 18, 2015 3:00PM - 3:12PM |
PO5.00006: Neutron Induced D Breakup in Inertial Confinement Fusion at the Omega Laser Facility C.J. Forrest, V.Yu. Glebov, J.P. Knauer, P.B. Radha, S.P. Regan, T.C. Sangster, C. Stoeckl, W.U. Schroder, J.A. Frenje, M. Gatu Johnson High-resolution neutron spectroscopy is used to study the deuteron breakup reaction D(n,n$\prime)$np in the thermonuclear environment created in inertial confinement fusion experiments at the Omega Laser Facility. Neutrons with an energy of 14.1 MeV generated in the primary D--T fusion reactions scatter elastically and inelastically off the dense (cryogenic) D--T fuel assembly surrounding the central hot spot at peak fuel compression. These neutrons also induce a breakup of the fuel deuterons. The corresponding breakup cross section is measured relative to elastic n$-$D and n$-$T scattering, i.e., simultaneously in the same environment. Apart from astrophysical and technological interest, the neutron-induced deuteron breakup reaction is of interest to the physics of nucleon$-$nucleon forces. For example, theoretical calculations predict a noticeable influence of nucleonic three-body forces on the magnitude of the breakup cross section. Preliminary results from measurements of the neutron contribution in the 2- to 6-MeV range show reasonable agreement with the published ENDL 2008.2 semi-empirical cross-section. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944. [Preview Abstract] |
Wednesday, November 18, 2015 3:12PM - 3:24PM |
PO5.00007: Neutron Time-of-Flight Measurements of Charged-Particle Energy Loss in Inertial Confinement Fusion Plasmas Daniel Sayre, Charlie Cerjan, Laura Berzak Hopkins, Joseph Caggiano, Laurent Divol, Mark Eckart, Frank Graziani, Gary Grim, Ed Hartouni, Robert Hatarik, Sebastien Le Pape, Andrew Mackinnon, Dieter Schneider, Scott Sepke Neutron time-of-flight measurements of inflight T$(d,n)\alpha$ reactions created during an implosion of a deuterium gas target have been performed at the National Ignition Facility, with order of magnitude improvements in statistics and resolution over past experiments. In the implosion, energetic tritons emitted by thermonuclear fusion within the deuterium plasma produced over $10^{11}$ inflight T$(d,n)\alpha$ reactions. The yield and particle spectrum of inflight reactions are sensitive to the triton's energy loss in the plasma, which, in this implosion, consisted of multi-keV temperatures and number densities above $10^{24}$ cm$^{-3}$. Radiation-hydrodynamic simulations of the implosion were adjusted to match the yield and broadening of the D$(d,n){}^{3}$He neutron peak. These same simulations give reasonable agreement with the measured T$(d,n)\alpha$ yield and neutron spectrum, and this provides a strong consistency check of the simulated plasma conditions and energy loss model. [Preview Abstract] |
Wednesday, November 18, 2015 3:24PM - 3:36PM |
PO5.00008: Plasma Stopping Power Measurements Relevant to Inertial Confinement Fusion Aaron McEvoy, Hans Herrmann, Yongho Kim, Nelson Hoffman, Mark Schmitt, Michael Rubery, Warren Garbett, Colin Horsfield, Steve Gales, Alex Zylstra, Maria Gatu Johnson, Johan Frenje, Richard Petrasso, Frederic Marshall, Steve Batha Ignition in inertial confinement fusion (ICF) experiments may be achieved if the alpha particle energy deposition results in a thermonuclear burn wave induced in the dense DT fuel layer surrounding the hotspot. As such, understanding the physics of particle energy loss in a plasma is of critical importance to designing ICF experiments. Experiments have validated various stopping power models under select n$_{e}$ and T$_{e}$ conditions, however there remain unexplored regimes where models predict differing rates of energy deposition. An upcoming experiment at the Omega laser facility will explore charged particle stopping in CH plastic capsule ablators across a range of plasma conditions (n$_{e}$ between 10$^{24}$ cm$^{-3}$ and 10$^{25}$ cm$^{-3}$ and T$_{e}$ on the order of hundreds of eV). Plasma conditions will be measured using x-ray and gamma ray diagnostics, while plasma stopping power will be measured using charged particle energy loss measurements. Details on the experiment and the theoretical models to be tested will be presented. [Preview Abstract] |
Wednesday, November 18, 2015 3:36PM - 3:48PM |
PO5.00009: The MRSt for time-resolved measurements of the neutron spectrum at the NIF J. Frenje, M. Gatu Johnson, C. Li, F. Seguin, R. Petrasso, T. Hilsabeck, J. Kilkenny, R. Bionta, C. Cerjan Information about the time evolution of inertial-confinement-fusion fuel assembly and hot-spot formation can be obtained with the next-generation Magnetic Recoil Spectrometer (MRS) for time-resolved measurements of the neutron spectrum. This spectrometer, called MRSt, represents a paradigm shift in our thinking about neutron spectrometers for ICF applications, as it will provide simultaneously information about the burn history and $\rho R$-$T_{i}$ trajectory during burn. As the peak burn generally occurs before and after peak compression in failed and ignited implosions, respectively, an MRSt measurement of the relative timing of these events will be critical for assessing implosion dynamics. [Preview Abstract] |
Wednesday, November 18, 2015 3:48PM - 4:00PM |
PO5.00010: A New Neutron Time-of-Flight Detector for DT Yield and Ion-Temperature Measurements on OMEGA V.Yu. Glebov, C.J. Forrest, J.P. Knauer, S.P. Regan, T.C. Sangster, C. Stoeckl A new neutron time-of-flight (nTOF) detector for DT yield and ion-temperature measurements in DT implosions on the OMEGA Laser System was designed, fabricated, tested, and calibrated. The goal of this detector is to provide a second line of sight for DT yield and ion-temperature measurements in the $1 \times 10^{12}$ to $10^{14}$ yield range. The nTOF detector consists of a 40-mm-diam, 20-mm-thick BC-422Q(1{\%}) scintillator coupled with a one-stage Photek PMT-140 photomultiplier tube. To avoid PMT saturation at high yields a neutral density filter ND1 is inserted between the scintillator and PMT. Both the scintillator and PMT are shielded from hard x rays by 5 mm of lead on all sides and 10 mm in the direction of the target. The nTOF detector is located at 15.8 m from target chamber center in the OMEGA Target Bay. The design details and calibration results of this nTOF detector in DT implosions on OMEGA will be presented. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944. [Preview Abstract] |
Wednesday, November 18, 2015 4:00PM - 4:12PM |
PO5.00011: Time-dependent neutron energy diagnostic Cindy R. Christensen The NTOF diagnostic used in ICF experiments uses detectors placed far from the source to remove the influence of the neutron time history, and give only energy information, averaged over emission time. Unfortunately, this information is easily misinterpreted. The Gamma Reaction History diagnostic is not susceptible to thermal dispersion, but by that fact does not tell us anything about the source thermal energy distribution. A wealth of information is potentially available from an array of neutron detectors placed over a wide range of distances from the source, whose signals are combined mathematically to infer an arbitrary source energy distribution as a function of time. A Maxwellian plasma is not assumed. Simultaneously, the source time history (total neutrons per second) is obtained. Simulations using representative instrument response functions are used to show the effects of noise, and the quality of signal available as a function of yield and the number and spacing of detectors. [Preview Abstract] |
Wednesday, November 18, 2015 4:12PM - 4:24PM |
PO5.00012: Abstract Withdrawn
|
Wednesday, November 18, 2015 4:24PM - 4:36PM |
PO5.00013: ``Super'' Gas Cherenkov Detector for Gamma Ray Measurements at the National Ignition Facility Hans W. Herrmann, Y.H. Kim, A.M. McEvoy, A.B. Zylstra, F.E. Lopez, J.R. Griego, V.E. Fatherley, J.A. Oertel, S.H. Batha, W. Stoeffl, J.A. Church, A. Carpenter, M.S. Rubery, C.J. Horsfield, S. Gales, A. Leatherland, T. Hilsabeck, J.D. Kilkenny, R.M. Malone, W.T. Shmayda New requirements to improve reaction history and ablator areal density measurements at the NIF necessitate improvements in sensitivity, temporal and spectral response relative to the existing Gamma Reaction History diagnostic (GRH-6m) located 6 meters from target chamber center (TCC). A new DIM-based ``Super'' Gas Cherenkov Detector (GCD) will ultimately provide $\sim$ 200x more sensitivity to DT fusion gamma rays, reduce the effective temporal resolution from $\sim$ 100 to $\sim$ 10 ps and lower the energy threshold from 2.9 to 1.8 MeV, relative to GRH-6m. The first phase is to insert the existing coaxial GCD-3 detector [1] into a reentrant well on the NIF chamber which will put it within 4 meters of TCC. This diagnostic platform will allow assessment of the x-ray radiation background environment within the well which will be fed into the shielding design for the follow-on ``Super'' GCD. It will also enable use of a pulse-dilation PMT which has the potential to improve the effective measurement bandwidth by $\sim$ 10x relative to current PMT technology. GCD-3 has been thoroughly tested at the OMEGA Laser Facility and characterized at the High Intensity Gamma Ray Source (HIgS). \\[4pt] [1] H.W. Herrmann, et al., Rev. Sci. Instrum. 85, 11E124 (2014) [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