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

NIF-0707-13723.ppt R. Boyd 07/31/07 2

NIF has 3 Missions

National Ignition Facility

Peer-reviewed Basic Science is a fundamental part of NIF’s go-forward plan

Stockpile Stewardship

BasicScience

FusionEnergy

NIF-0707-13723.ppt R. Boyd 07/31/07 3

Our vision: open NIF to the outside scientific community to pursue frontier HED laboratory science

Element formation in stars

The Big BangPlanetary system formation

Forming Earth-like planets

Chemistry of life

[http://www.nas.edu/bpa/reports/cpu/index.html

NIF-0707-13723.ppt R. Boyd 07/31/07 4

NIF-0707-13723.ppt R. Boyd 07/31/07 5

The implosion process is similar forboth direct and indirect drive

Spherical ablation with pulse shaping results in a rocket-like implosion of near Fermi-degenerate fuel

Low-z Ablator forefficient absorption

Cryogenic Fuel for efficient compression

DTgas

Spherical collapse of the shell produces a central hot spot surrounded by cold, dense main fuel

Hot spot(10 keV)

Cold, dense mainFuel (1000 g/cm3)

2 mm 100 m

t = 15 nst = 0

NIF-0707-13723.ppt R. Boyd 07/31/07 6

We have already fielded ~ half of all the types of diagnostic systems needed for NIF science

Full ApertureBackscatter

Diagnostic Instrument Manipulator (DIM)

Diagnostic Instrument Manipulator (DIM)

X-ray imager

Streaked x-ray detector

VISAR

Velocity Measurements

Static x-rayimager

FFLEX

Hard x-ray spectrometer

Near Backscatter Imager

DANTE

Soft x-ray temperature

Diagnostic Alignment System

Cross Timing System

We have 30 types of diagnosticsystems planned for NIC

NIF-0707-13723.ppt R. Boyd 07/31/07 7

NIF-0707-13723.ppt R. Boyd 07/31/07 8

NIF’s Unprecedented Scientific Environments:

• T >108 K matter temperature • >103 g/cc density

Those are both 7x what the Sun does! Helium burning, stage 2 instellar evolution, occurs at 2x108 K!

• n = 1019 neutrons/cc

Core-collapse Supernovae, colliding neutron stars, operate at ~1020!

• Electron Degenerate conditions Rayleigh-Taylor instabilities for (continued) laboratory study.

These apply to Type Ia Supernovae!

• Pressure > 1011 bar

Only need ~Mbar in shocked hydrogen to study the EOS in Jupiter & Saturn

These certainly qualify as “unprecedented.” And Extreme!

NIF-0707-13723.ppt R. Boyd 07/31/07 9

NIF flux (cm-2s-1) vs other neutron sources

LANSCE/WNR Reactor SNS NIF

1033-36{

1014-16{

108-9{

1040

1020

100

Ne

utr

on

s/c

m2•s

1013-15{

Supernovae

NIF-0707-13723.ppt R. Boyd 07/31/07 10

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 researchopportunities in:

- Plasma physics

- Laser and particle beam physics

- Condensed matter and materials science

- Nuclear physics

- Atomic and molecular physics

- Fluid dynamics

- Magnetohydrodynamics

- Astrophysics

NIF-0707-13723.ppt R. Boyd 07/31/07 11

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

NIF-0707-13723.ppt R. Boyd 07/31/07 12

Experiments on NIF can address key physics questions throughout the stellar life cycle

Stellar life Stellar death

Supernova shocks

Opacities, EOS Turbulenthydro

rad flow

Stellar post-mortem

Photoionizedplasma

Ques. 6(Cosmicaccel.)

Ques. 2, 10(Dark energy;the elements)

Ques. 4, 8(Gravity;HED matter)

Ques. 2, 10(Dark energy;the elements)

Particle acceleration

NIF-0707-13723.ppt R. Boyd 07/31/07 13

Core-collapse supernova explosion mechanisms remain uncertain

6 x 109cm

• 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)]

Densityt = 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

1012cm

9 x

109 c

m

NIF-0707-13723.ppt R. Boyd 07/31/07 14

Core-collapse supernova explosionmechanisms 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

NIF-0707-13723.ppt R. Boyd 07/31/07 15

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)]

P0 (days)

P1 / P

0

0.74

0.70

0.72OPAL

Cox Tabor

6M

5M

4M4M 5M6M

7M

Observations

Log T(K)

Lo

g k

R (c

m2 /

g)

Fe M shell

Fe L shell andC, O, Ne K shell

HHe+

H,He

Los Alamos, Z = 0.02OPAL, Z = 0.00

OPAL, Z = 0.02

Ar, Fe K shell

2

1

0

-11 3 5 74 5 6 7 8

NIF-0707-13723.ppt R. Boyd 07/31/07 16

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 cantest the models used to interpret accreting compact objects

Accretion Disk Model

ini neCini ne i1ni1

ni1ni

Ci i1

1 iCi

Lx (ergs/s)

ner2

[Jimenez - Garate et al., Ap.J. 581, 1297 (2002)]

102 103Chandra Spectrum of Cyg X-3 X-ray Binary

[Paerels et al., Ap.J. Lett 533, L135 (2000)]

Red-Giant star

109 - 1010 cm

Neutronstar i

Atmosphereand Corona

Clouds

Accretion disk

1010 - 1011 cm

106 cm

120

80

40

0

Co

un

ts

3 4 5 6 7Wavelength (Å)

Accretion stream

NIF-0707-13723.ppt R. Boyd 07/31/07 17

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

Tr = 165 eVTe = 150 eVTi = 150 eV

Ch

arg

e st

ate

frac

tio

nNIMP, w/o rad.

[R.F. Heeter et al., RSI 72, 1224 (2001)]

Wavelength 0.77 keV0.99 keV

12 13 14 15 16-500

0

500

1000

1500

2000

Inte

nsi

ty

Exp’l dataNIMP, w/ rad.

• Experiments at ~20, demonstrated at ‘Z’

• Astrophysics codes disagree on line shape and <Z> by up to ~2x, showing the need for laboratory data

• NIF will allow the astrophysics relevant regimes of ~ 102-103 to be accessed

0.0

0.2

0.4

0.6

0.8GALAXY, w/ rad.

14 15 16 17 18 19

NIF-0707-13723.ppt R. Boyd 07/31/07 18

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

NIF-0707-13723.ppt R. Boyd 07/31/07 19

Solid-state materials science and lattice dynamics at ultrahigh pressures and strain rates define a new frontier of condensed matter science

Lattice Dynamics Phase Diagram of Iron

2000

1000

00 10 20

Pressure (GPa)

Tem

per

atu

re (

K)

Unexplored regimes of solid-state dynamics at

extremely high pressures and strain rates will be accessible

on NIF

Dynamic Diffraction Lattice Msmt

Iron,Pshk ~20 GPa

[D.H. Kalantar et al., PRL 95 ,075502 (2005); J. Hawreliak et al., PRB, in press (2006)]

NIF-0707-13723.ppt R. Boyd 07/31/07 21

Three university teams are starting to prepare for NIF shots in unique regimes of HED physics

Planetaryphysics - 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 BerkeleyThomas Duffy, Princeton U.Russell Hemley, Carnegie Inst.Yogendra Gupta, Wash. State U.Paul Loubeyre, U. Pierre & Marie Curie, and CEALLNL EOS team

Christoph Niemann, PI, UCLA NIF ProfessorChan Joshi, UCLAWarren Mori, UCLABedros Afeyan, PolymathDavid Montgomery, LANLAndrew Schmitt, NRLLLNL LPI team

Astrophysics -hydrodynamics

Nonlinear optical physics - LPI

NIF-0707-13723.ppt R. Boyd 07/31/07 22

Exc

itat

ion

Ene

rgy

Spin ( )

10 15 11s

10 15 12 s}

10 12 9 s}

10 18 15 s

Exc

itat

ion

Ene

rgy

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

NIF-0707-13723.ppt R. Boyd 07/31/07 23

A-3 A-2 A-1 AA-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 Ex≈Sn 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 (En>14 MeV) neutrons (103-5 fewer than at 14 MeV) do (n,3n) on

ground states

NIF-0707-13723.ppt R. Boyd 07/31/07 24

Assumptions

• 5 x 1015 neutrons

— Higher yield shots produce a weaker signal due to competition from multi-step (n,2n)

• 250 µm initial diameter

• bin = 50 fs

• 1:103 high energy “tertiaries”— Tertiaries also mask

excited state effects

NIF allows us to measure the lifetimes of highly excited states

0.000

0.001

0.001

0.002

0.002

A-2/A-1 A-3/A-2 A-4/A-3

0.5 fs Excited States

5 fs excited states

50 fs 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

0.002

0.001

0.001

0.000A-2/A-1 A-3/A-2 A-4/A-3

Ratio

Val

ue

NIF-0707-13723.ppt R. Boyd 07/31/07 25

Stellar Hydrogen-Burning Reactions

NIF-0707-13723.ppt R. Boyd 07/31/07 26

Comparison of 3He(4He,)7Be measured at an accelerator lab and using NIF

NIF-Based Experiments

E (keV)

0.2

0.4

Gamow window

0 400 800

S-F

acto

r (k

eV. b

arn

)

Resonance

Accelerator-Based Experiments

Mono-energetic

Energy too high

Low event rate (few events/month)

Not performed at relevant energies

High Count rate (3x105 atoms/shot)

Energy window is better

Integral experiment

7Be background

1017 3Heatoms

CHAblator

DT

Ice

DT Gas

0.63He(4He,)7Be

XX

XX

NIF-0707-13723.ppt R. Boyd 07/31/07 28

A unique NIF opportunity: Study ofa 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 ++n9Be reaction

Abu

ndan

ce a

fter

d

ecay

60 80 100 120 140 160 180 200 220Mass Number (A)

NIF-0707-13723.ppt R. Boyd 07/31/07 29

8Be

During its 10-16 s half-life, a 8Be can capture a neutron to make 9Be, in the r-process environment, and even in the NIF target n

9Be

• If this reaction is strong, 9Be becomes abundant, +9Be 12C+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 12C 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 2H and 3H, to make the neutrons, with some 4He (and more 4He will be made during ignition). This type of experiment can’t be done with any other facility that has ever existed

+n9Be is the “Gatekeeper” for the r-Process

NIF-0707-13723.ppt R. Boyd 07/31/07 30

• 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

NIF-0707-13723.ppt R. Boyd 07/31/07 31