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The National Ignition Facility and Basic Science Work performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48. Richard N. Boyd Science Director, National Ignition Facility July 31, 2007 Presentation to San Diego Summer School
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NIF-0707-13723.pptR. Boyd 07/31/072 NIF has 3 Missions National Ignition Facility Peer-reviewed Basic Science is a fundamental part of NIF’s go-forward plan Stockpile Stewardship Basic Science Fusion Energy
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NIF-0707-13723.pptR. Boyd 07/31/073 Our vision: open NIF to the outside scientific community to pursue frontier HED laboratory science Element formation in stars The Big Bang Planetary system formation Forming Earth-like planets Chemistry of life [http://www.nas.edu/bpa/reports/cpu/index.html
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NIF-0707-13723.pptR. Boyd 07/31/074
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NIF-0707-13723.pptR. Boyd 07/31/075 The implosion process is similar for both direct and indirect drive Spherical ablation with pulse shaping results in a rocket-like implosion of near Fermi- degenerate fuel Low-z Ablator for efficient absorption Cryogenic Fuel for efficient compression DT gas Spherical collapse of the shell produces a central hot spot surrounded by cold, dense main fuel Hot spot (10 keV) Cold, dense main Fuel (1000 g/cm 3 ) 2 mm 100 m t = 15 nst = 0
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NIF-0707-13723.pptR. Boyd 07/31/076 We have already fielded ~ half of all the types of diagnostic systems needed for NIF science Full Aperture Backscatter Diagnostic Instrument Manipulator (DIM) X-ray imager Streaked x-ray detector VISAR Velocity Measurements Static x-ray imager FFLEX Hard x-ray spectrometer Near Backscatter Imager DANTE Soft x-ray temperature Diagnostic Alignment System Cross Timing System We have 30 types of diagnostic systems planned for NIC
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NIF-0707-13723.pptR. Boyd 07/31/077
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NIF-0707-13723.pptR. Boyd 07/31/078 NIF’s Unprecedented Scientific Environments: T >10 8 K matter temperature >10 3 g/cc density Those are both 7x what the Sun does! Helium burning, stage 2 in stellar evolution, occurs at 2x10 8 K! n = 10 19 neutrons/cc Core-collapse Supernovae, colliding neutron stars, operate at ~10 20 ! Electron Degenerate conditions Rayleigh-Taylor instabilities for (continued) laboratory study. These apply to Type Ia Supernovae! Pressure > 10 11 bar Only need ~Mbar in shocked hydrogen to study the EOS in Jupiter & Saturn These certainly qualify as “unprecedented.” And Extreme!
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NIF-0707-13723.pptR. Boyd 07/31/079 NIF flux (cm -2 s -1 ) vs other neutron sources LANSCE/WNR Reactor SNS NIF 10 33-36 { 10 14-16 { 10 8-9 { 10 40 10 20 10 0 Neutrons/cm 2 s 10 13-15 { Supernovae
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NIF-0707-13723.pptR. Boyd 07/31/0710 The NRC committee on HEDP issued the “X- Games” report detailing this new science frontier Findings: NIF is the premier facility for exploring extreme conditions of HEDP HEDP offers frontier research opportunities in: - Plasma physics - Laser and particle beam physics - Condensed matter and materials science - Nuclear physics - Atomic and molecular physics - Fluid dynamics - Magnetohydrodynamics - Astrophysics
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NIF-0707-13723.pptR. Boyd 07/31/0711 The NRC committee on the Physics of the Universe highlighted the new frontier of HED Science HEDP provides crucial experiments to interpret astrophysical observations The field should be better coordinated across Federal agencies Eleven science questions for the new century: 2. What is the nature of dark energy? — Type 1A SNe (burn, hydro, rad flow, EOS, opacities) 6. How do cosmic accelerators work and what are they accelerating? — Cosmic rays (strong field physics, nonlinear plasma waves) 4. Did Einstein have the last word on gravity? — Accreting black holes (photoionized plasmas, spectroscopy) 8. Are there new states of matter at exceedingly high density and temperature? — Neutron star interior (photoionized plasmas, spectroscopy, EOS) 10. How were the elements from iron to uranium made and ejected? — Core-collapse SNe (reactions off excited states, turbulent hydro, rad flow) NATIONAL RESEARCH COUNCIL OF THE NATIONAL ACADEMIES
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NIF-0707-13723.pptR. Boyd 07/31/0712 Experiments on NIF can address key physics questions throughout the stellar life cycle Stellar life Stellar death Supernova shocks Opacities, EOS Turbulent hydro rad flow Stellar post-mortem Photoionized plasma Ques. 6 (Cosmic accel.) Ques. 2, 10 (Dark energy; the elements) Ques. 4, 8 (Gravity; HED matter) Ques. 2, 10 (Dark energy; the elements) Particle acceleration
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NIF-0707-13723.pptR. Boyd 07/31/0713 Core-collapse supernova explosion mechanisms remain uncertain 6 x 10 9 cm SN observations suggest rapid core penetration to the “surface” This observed turbulent core inversion is not yet fully understood Standard (spherical shock) model [Kifonidis et al., AA. 408, 621 (2003)] Density t = 1800 sec Jet model [Khokhlov et al., Ap.J.Lett. 524, L107 (1999)] Pre-supernova structure is multilayered Supernova explodes by a strong shock Turbulent hydrodynamic mixing results Core ejection depends on this turbulent hydro. Accurate 3D modeling is required, but difficult Scaled 3D testbed experiments are possible 10 12 cm 9 x 10 9 cm
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NIF-0707-13723.pptR. Boyd 07/31/0714 Core-collapse supernova explosion mechanisms remain uncertain A new model of Supernova explosions: from Adam Burrows et al. A cutaway view shows the inner regions of a star 25 times more massive than the sun during the last split second before exploding as a SN, as visualized in a computer simulation. Purple represents the star’s inner core; Green (Brown) represents high (low) heat content From http://www.msnbc.msn.com/id/11463498/ In the Burrows model, after about half a second, the collapsing inner core begins to vibrate in “g-mode” oscillations. These grow, and after about 700 ms, create sound waves with frequencies of 200 to 400 hertz. This acoustic power couples to the outer regions of the star with high efficiency, causing the SN to explode Burrows’ solution hasn’t been accepted by everyone; it’s very different from any previously proposed
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NIF-0707-13723.pptR. Boyd 07/31/0715 Opacity experiments on iron led to an improved understanding of Cepheid Variable pulsation The measured opacities of Fe under relevant conditions were larger than originally calculated New OPAL simulations reproduced the data The new opacity simulations allowed Cepheid Variable pulsations to be correctly modeled “Micro input physics” affecting the “macro output dynamics” [Rogers & Iglesias, Science 263,50 (1994); Da Silva et al., PRL 69, 438 (1992)] P 0 (days) P 1 / P 0 0.74 0.70 0.72 OPAL Cox Tabor 6M 5M 4M 5M 6M 7M Observations Log T(K) Log k R (cm 2 /g) Fe M shell Fe L shell and C, O, Ne K shell H He + H, He Los Alamos, Z = 0.02 OPAL, Z = 0.00 OPAL, Z = 0.02 Ar, Fe K shell 2 1 0 1357 45678
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NIF-0707-13723.pptR. Boyd 07/31/0716 Accreting neutron stars and black holes are observed through the x-ray spectral emissions from the surrounding photoionized plasma Scaled experiments of photoionized plasmas on NIF can test the models used to interpret accreting compact objects Accretion Disk Model [Jimenez - Garate et al., Ap.J. 581, 1297 (2002)] Chandra Spectrum of Cyg X-3 X-ray Binary [Paerels et al., Ap.J. Lett 533, L135 (2000)] Red-Giant star 10 9 - 10 10 cm Neutron star i Atmosphere and Corona Clouds Accretion disk 10 10 - 10 11 cm 10 6 cm 120 80 40 0 Counts 34567 Wavelength (Å) Accretion stream
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NIF-0707-13723.pptR. Boyd 07/31/0717 Experiments on the Z magnetic pinch facility have demonstrated x-ray photoionized plasmas [S. Rose et al., J. Phys. B: At. Mol. Opt. Phys. 37, L337 (2004)] Iron charge state T r = 165 eV T e = 150 eV T i = 150 eV Charge state fraction NIMP, w/o rad. [R.F. Heeter et al., RSI 72, 1224 (2001)] Wavelength 0.77 keV0.99 keV 1213141516 -500 0 500 1000 1500 2000 Intensity Exp’l data NIMP, w/ rad. Experiments at ~20, demonstrated at ‘Z’ Astrophysics codes disagree on line shape and by up to ~2x, showing the need for laboratory data NIF will allow the astrophysics relevant regimes of ~ 10 2 -10 3 to be accessed 0.0 0.2 0.4 0.6 0.8 GALAXY, w/ rad. 141516171819
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NIF-0707-13723.pptR. Boyd 07/31/0718 NIF will be able to create and characterize a wide range of high - (P, ) states of matter found in the interiors of planets Fundamental questions in planetary formation models can be addressed on NIF
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NIF-0707-13723.pptR. Boyd 07/31/0719 Solid-state materials science and lattice dynamics at ultrahigh pressures and strain rates define a new frontier of condensed matter science Lattice DynamicsPhase Diagram of Iron 2000 1000 0 01020 Pressure (GPa) Temperature (K) Unexplored regimes of solid-state dynamics at extremely high pressures and strain rates will be accessible on NIF Dynamic Diffraction Lattice Msmt Iron, P shk ~ 20 GPa [D.H. Kalantar et al., PRL 95,075502 (2005); J. Hawreliak et al., PRB, in press (2006)]
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NIF-0707-13723.pptR. Boyd 07/31/0721 Three university teams are starting to prepare for NIF shots in unique regimes of HED physics Planetary physics - EOS Paul Drake, PI, U. of Mich. David Arnett, U. of Arizona, Adam Frank, U. of Rochester, Tomek Plewa, U. of Chicago, Todd Ditmire, U. Texas-Austin LLNL hydrodynamics team Raymond Jeanloz, PI, UC Berkeley Thomas Duffy, Princeton U. Russell Hemley, Carnegie Inst. Yogendra Gupta, Wash. State U. Paul Loubeyre, U. Pierre & Marie Curie, and CEA LLNL EOS team Christoph Niemann, PI, UCLA NIF Professor Chan Joshi, UCLA Warren Mori, UCLA Bedros Afeyan, Polymath David Montgomery, LANL Andrew Schmitt, NRL LLNL LPI team Astrophysics - hydrodynamics Nonlinear optical physics - LPI
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NIF-0707-13723.pptR. Boyd 07/31/0722 Excitation Energy Spin ( ) } } Excitation Energy Spin ( ) NIF “target” states NIF will cause reactions on non-isomeric short-lived states The short time scale of a NIF burn matches the lifetime of “quasi-continuum” states
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NIF-0707-13723.pptR. Boyd 07/31/0723 A-3A-2A-1AA-4 This type of analysis is quantitatively understood at LLNL A simple toy model can be used to model reactions on excited states at NIF Divide NIF “burn” time into 100 equal-flux time bins ( t≈50-400 fs) Assume 14 MeV neutrons induce (n,3n) rather than (n,2n) on all nuclei still at E x ≈S n after 1 bin and that these nuclei Include two neutron energy bins: —14 MeV: can do (n,n’) & (n,2n) on ground and (n,3n) on excited states —Tertiary (E n >14 MeV) neutrons (10 3-5 fewer than at 14 MeV) do (n,3n) on ground states
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NIF-0707-13723.pptR. Boyd 07/31/0724 Assumptions 5 x 10 15 neutrons —Higher yield shots produce a weaker signal due to competition from multi-step (n,2n) 250 µm initial diameter bin = 50 fs 1:10 3 high energy “tertiaries” —Tertiaries also mask excited state effects NIF allows us to measure the lifetimes of highly excited states Reactions on excited states are responsible for almost all of the higher order (n,xn) products at NIF Reaction Product Ratios for Different Excited State Lifetimes 0.002 0.001 0.000 A-2/A-1A-3/A-2A-4/A-3 Ratio Value
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NIF-0707-13723.pptR. Boyd 07/31/0725 Stellar Hydrogen-Burning Reactions
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NIF-0707-13723.pptR. Boyd 07/31/0726 Comparison of 3 He( 4 He, ) 7 Be measured at an accelerator lab and using NIF NIF-Based Experiments E (keV) 0.2 0.4 Gamow window 0 400 800 S-Factor (keV. barn) Resonance Accelerator-Based Experiments Mono-energetic Energy too high Low event rate (few events/month) Not performed at relevant energies High Count rate (3x10 5 atoms/shot) Energy window is better Integral experiment 7 Be background 10 17 3 He atoms CH Ablator DT Ice DT Gas 0.6 3 He( 4 He, ) 7 Be X X X X
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NIF-0707-13723.pptR. Boyd 07/31/0727 Thermonuclear Reaction Rates between species i and j are of the form: S factors are extrapolated to the relevant stellar Gamow ‘weighting’ regions from higher energy experimental data – laboratory ‘cold’ electron screening effects are significant Thermonuclear reactions can be observed in ‘passive’ NIF implosions or as by products of the temperature runaway in d + t burn -but measurement challenging! 3 He( 3 He,2p) ~ 10 8 reactions at 8 keV in 20 ps (10 17 initial nuclei, note ‘targets’) 7 Be(p, ) 8 B ~ 4 x 10 4 reactions 3 He( 7 Be ~ 3 x 10 5 reactions 15 N(p, ) 12 C ~ 6 x 10 6 reactions Stellar Astrophysics at NIF: Measurements of Basic Thermonuclear Reactions
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NIF-0707-13723.pptR. Boyd 07/31/0728 A unique NIF opportunity: Study of a Three-Body Reaction in the r-Process Currently believed to take place in supernovae, but we don’t know for sure r-process abundances depend on: Nuclear Masses far from stability —Weak decay rates far from stability The cross section for the + +n 9 Be reaction Abundance after decay 6080 100 120 140 160 180 200 220 Mass Number (A)
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NIF-0707-13723.pptR. Boyd 07/31/0729 8 Be During its 10 -16 s half-life, a 8 Be can capture a neutron to make 9 Be, in the r-process environment, and even in the NIF target n 9 Be If this reaction is strong, 9 Be becomes abundant, + 9 Be 12 C+n is frequent, and the light nuclei will all have all been captured into the seeds by the time the r-Process seeds get to ~Fe If it’s weak, less 12 C is made, and the seeds go up to mass 100 u or so; this seems to be what a successful r-Process (at the neutron star site) requires The NIF target would be a mixture of 2 H and 3 H, to make the neutrons, with some 4 He (and more 4 He will be made during ignition). This type of experiment can’t be done with any other facility that has ever existed +n 9 Be is the “Gatekeeper” for the r-Process
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NIF-0707-13723.pptR. Boyd 07/31/0730 HEDP provides crucial experiments to interpreting astrophysical observations We envision that NIF will play a key role in these measurements Eleven science questions for the new century: 2. What is the nature of dark energy? — Type 1A SNe (burn, hydro, rad flow, EOS, opacities) 6. How do cosmic accelerators work and what are they accelerating? — Cosmic rays (strong field physics, nonlinear plasma waves) 4. Did Einstein have the last word on gravity? — Accreting black holes (photoionized plasmas, spectroscopy) 8. Are there new states of matter at exceedingly high density and temperature? — Neutron star interior (photoionized plasmas, spectroscopy, EOS) 10. How were the elements from iron to uranium made and ejected? — Core-collapse SNe (reactions off excited states, turbulent hydro, rad flow) NATIONAL RESEARCH COUNCIL OF THE NATIONAL ACADEMIES The NRC committee on the Physics of the Universe highlighted the new frontier of HED Science
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