The National Ignition Facility and Basic Science
Presentation to
San Diego Summer School
Richard N. Boyd
Science Director, National Ignition Facility
July 31, 2007
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.
NIF has 3 Missions
National Ignition Facility
Stockpile
Stewardship
Basic
Science
Fusion
Energy
Peer-reviewed Basic Science is a fundamental part of NIF’s go-forward plan
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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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The implosion process is similar for
both direct and indirect drive
t=0
t = 15 ns
Low-z Ablator for
efficient absorption
2 mm
Cold, dense main
Fuel (1000 g/cm3)
DT
gas
100 m
Cryogenic Fuel for
efficient compression
Hot spot
(10 keV)
Spherical ablation with pulse
shaping results in a rocket-like
implosion of near Fermidegenerate fuel
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Spherical collapse of the shell
produces a central hot spot
surrounded by cold, dense main
fuel
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We have 30 types of diagnostic
systems planned for NIC
Diagnostic
Alignment
System
Diagnostic
Instrument
Manipulator (DIM)
Near Backscatter
Imager
FFLEX
Hard x-ray
spectrometer
X-ray imager
Streaked
x-ray detector
Diagnostic
Instrument
Manipulator
(DIM)
DANTE
Soft x-ray
temperature
Static x-ray
imager
Full
Aperture
Backscatter
Cross
Timing
System
VISAR
Velocity
Measurements
We have already fielded ~ half of all the types of
diagnostic systems needed for NIF science
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NIF’s Unprecedented Scientific Environments:
• T >108 K matter temperature
• r >103 g/cc density
Those are both 7x what the Sun does! Helium burning, stage 2 in
stellar evolution, occurs at 2x108 K!
• rn = 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!
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NIF flux (cm-2s-1) vs other neutron sources
1040
Supernovae
Neutrons/cm2•s
1033-36
1020
1014-16
{
{
1013-15{
108-9{
100
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LANSCE/WNR
Reactor
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SNS
NIF
9
The NRC committee on HEDP issued the “XGames” report detailing this new science frontier
Findings:
• 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
NIF is the premier facility for exploring extreme conditions of HEDP
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The NRC committee on the Physics of the Universe
highlighted the new frontier of HED Science
Eleven science questions for the new century:
2. What is the nature of dark energy?
— Type 1A SNe (burn, hydro, rad flow, EOS, opacities)
4. Did Einstein have the last word on gravity?
— Accreting black holes (photoionized
plasmas, spectroscopy)
6. How do cosmic accelerators work and
what are they accelerating?
— Cosmic rays (strong field physics, nonlinear
plasma waves)
8. Are there new states of matter at exceedingly
high density and temperature?
— Neutron star interior (photoionized plasmas,
spectroscopy, EOS)
NATIONAL RESEARCH COUNCIL
OF THE NATIONAL ACADEMIES
10. How were the elements from iron to
uranium made and ejected?
— Core-collapse SNe (reactions off excited states,
turbulent hydro, rad flow)
• HEDP provides crucial experiments to interpret astrophysical observations
• The field should be better coordinated across Federal agencies
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Experiments on NIF can address key physics
questions throughout the stellar life cycle
Ques. 2, 10
(Dark energy;
the elements)
Ques. 4, 8
(Gravity;
HED matter)
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Stellar life
Opacities, EOS
Stellar post-mortem
Photoionized
plasma
Ques. 2, 10
(Dark energy;
the elements)
Ques. 6
(Cosmic
accel.)
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Stellar death
Turbulent
hydro
rad flow
Supernova shocks
Particle
acceleration
12
Core-collapse supernova explosion
mechanisms remain uncertain
• SN observations suggest rapid core penetration to the “surface”
• This observed turbulent core inversion is not yet fully understood
Jet model
Standard (spherical shock) model
Density
9 x 109cm
t = 1800 sec
1012cm
[Kifonidis et al., AA. 408, 621 (2003)]
•
•
•
•
•
•
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
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6 x 109cm
[Khokhlov et al., Ap.J.Lett. 524,
L107 (1999)]
13
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
• 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
From http://www.msnbc.msn.com/id/11463498/
• Burrows’ solution hasn’t been accepted by everyone; it’s very different
from any previously proposed
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Opacity experiments on iron led to an improved
understanding of Cepheid Variable pulsation
2
6M
5M
OPAL
0.72
4M
5M
Observations
1
3
5
4M
6M
7M
Log kR (cm2/g)
0.74
0.70
Fe M
shell
Cox Tabor
7
H
1
H,
He
OPAL, Z = 0.02
Los Alamos,
Z = 0.02
OPAL, Z = 0.00
He+
Fe L shell and
C, O, Ne K shell
Ar, Fe
K shell
0
-1
P0 (days)
4
5
6
7
8
Log T(K)
[Rogers & Iglesias, Science 263,50 (1994);
Da Silva et al., PRL 69, 438 (1992)]
• 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”
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Accreting neutron stars and black holes are observed
through the x-ray spectral emissions from the
surrounding photoionized plasma
Accretion Disk Model
Atmosphere
and Corona
Neutron
star
Red-Giant
star
i
109 1010 cm
106 cm
Accretion stream
Clouds
1010 - 1011 cm
  10  10
2
Accretion disk
3
Chandra Spectrum of Cyg X-3 X-ray Binary
120
ini  neCini  ne i1ni1




Lx (ergs/s)
ne r 2
Counts
[Jimenez - Garate et al., Ap.J. 581, 1297 (2002)]
80
40
ni1 
Ci   i 

 
1 

 ni   i1  Ci 
0
3
4
5
Wavelength (Å)
6
7
[Paerels et al., Ap.J. Lett 533, L135 (2000)]
Scaled experiments of photoionized plasmas on NIF can
test the models used to interpret accreting compact objects

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Experiments on the Z magnetic pinch facility have
demonstrated x-ray photoionized plasmas
• Astrophysics codes
disagree on line shape and
<Z> by up to ~2x, showing
the need for laboratory data
1500
Intensity
• Experiments at ~20,
demonstrated at ‘Z’
2000
1000
500
0
-500
12
0.99 keV
13
14
15
Wavelength
16
0.77 keV
• NIF will allow the
astrophysics relevant
regimes of  ~ 102-103 to be
accessed
Charge state fraction
[R.F. Heeter et al., RSI 72, 1224 (2001)]
Exp’l data
NIMP, w/ rad.
0.8
GALAXY, w/ rad.
0.6
0.4
NIMP,
w/o rad.
0.2
0.0
14
Tr = 165 eV
Te = 150 eV
Ti = 150 eV
15 16
17
18
Iron charge state
19
[S. Rose et al., J. Phys. B: At. Mol. Opt. Phys. 37, L337 (2004)]
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Fundamental questions in planetary formation
models can be addressed on NIF
NIF will be able to create and characterize a wide range of
high - (P, r) states of matter found in the interiors of planets
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Solid-state materials science and lattice dynamics
at ultrahigh pressures and strain rates define a
new frontier of condensed matter science
Phase Diagram of Iron
Temperature (K)
Lattice Dynamics
2000
1000
0
Dynamic Diffraction Lattice Msmt
0
10
20
Pressure (GPa)
Iron,
Pshk ~
20 GPa
Unexplored regimes of
solid-state dynamics at
extremely high pressures and
strain rates will be accessible
on NIF
[D.H. Kalantar et al., PRL 95 ,075502 (2005);
J. Hawreliak et al., PRB, in press (2006)]
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Three university teams are starting to prepare
for NIF shots in unique regimes of HED physics
Astrophysics hydrodynamics
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
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Planetary
physics - EOS
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
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Nonlinear optical
physics - LPI
Christoph Niemann, PI,
UCLA NIF Professor
Chan Joshi, UCLA
Warren Mori, UCLA
Bedros Afeyan, Polymath
David Montgomery, LANL
Andrew Schmitt, NRL
LLNL LPI team
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The short time scale of a NIF burn matches the
lifetime of “quasi-continuum” states
  101815 s

  101511 s
Excitation Energy

NIF “target” states

}
  101512 s
}
  10129 s

Spin ( )
NIF will cause reactions on non-isomeric short-lived states
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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
A-4
A-3
A-2
A-1
A
This type of analysis is quantitatively understood at LLNL
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Reactions on excited states are responsible for almost
all of the higher order (n,xn) products at NIF
Assumptions
Reaction Product Ratios
for Different Excited State Lifetimes
• 5 x 1015 neutrons
— Higher yield shots
produce a weaker signal
due to competition from
multi-step (n,2n)
• bin = 50 fs
• 1:103 high energy “tertiaries”
— Tertiaries also mask
excited state effects
0.5 fs Excited States
5 fs excited states
50 fs Excited States
Value
0.002
0.002
Value
• 250 µm initial diameter
0.002
0.002
0.001
0.001
0.001
0.001
0.000
0.000
A-2/A-1
A-2/A-1
A-3/A-2
A-3/A-2
Ratio
A-4/A-3
A-4/A-3
Ratio
NIF allows us to measure the lifetimes of highly excited states
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Stellar Hydrogen-Burning Reactions
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Comparison of 3He(4He,)7Be measured at
an accelerator lab and using NIF
S-Factor (keV.barn)
Accelerator-Based Experiments
NIF-Based Experiments
CH
Ablator
3He(4He,)7Be
0.6
DT
Resonance
Ice
1017 3He
atoms
0.4
DT Gas
Gamow window
0.2
0

X
X
X
400
800
E (keV)
Low event rate (few events/month)



Not performed at relevant energies
X
Mono-energetic
Energy too high
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High Count rate (3x105 atoms/shot)
Energy window is better
Integral experiment
7Be
background
26
• 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9Be
reaction
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Abundance after  decay
A unique NIF opportunity: Study of
a Three-Body Reaction in the r-Process
60
80
100
120 140 160
Mass Number (A)
180 200 220
28
+n9Be is the “Gatekeeper” for the r-Process
• 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
9Be

-16
During its 10 s half-life,
8Be
a 8Be can capture a
neutron to make 9Be, in
the r-process
environment, and even in
the NIF target

n
• 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
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The NRC committee on the Physics of the Universe
highlighted the new frontier of HED Science
Eleven science questions for the new century:
2. What is the nature of dark energy?
— Type 1A SNe (burn, hydro, rad flow, EOS, opacities)
4. Did Einstein have the last word on gravity?
— Accreting black holes (photoionized
plasmas, spectroscopy)
6. How do cosmic accelerators work and
what are they accelerating?
— Cosmic rays (strong field physics, nonlinear
plasma waves)
8. Are there new states of matter at exceedingly
high density and temperature?
— Neutron star interior (photoionized plasmas,
spectroscopy, EOS)
NATIONAL RESEARCH COUNCIL
OF THE NATIONAL ACADEMIES
10. How were the elements from iron to
uranium made and ejected?
— Core-collapse SNe (reactions off excited states,
turbulent hydro, rad flow)
• HEDP provides crucial experiments to interpreting astrophysical observations
• We envision that NIF will play a key role in these measurements
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