Science under Extreme Conditions
Presented to:NAS Meeting of the Board on
Physics and Astronomy
Presented by:Dr. C. Deeney
Director, Office of Inertial Confinement Fusion
April 24, 2009
2
Outline
• Science under extreme conditions within NNSA
– New facilities
– Ignition as a grand challenge
• HEDP Science, nuclear science and dynamic materials science – recent results
• NNSA/Office of Science - joint sponsors of HEDLP
• Conclusions
3
Understanding states of matter over a wide range of temperatures and pressures is at the heart of NNSA
Omega
••
4
Computational science and experimental science must be integrated from the atomic- to the continuum-level to predict the properties of materials under extreme conditions
Static 10–4 – 102 s–1 102 – 105 s–1 105 – 109 s–1
nm
µm
m
e–
Continuum
Microscale
Atomic Scale
Computational Materials Computational Materials SciencesSciences
Strain Rates
Len
gth
sca
les
Experimental platformsExperimental platforms
Gas Gun
Pulsed power Pulsed power
Lasers Lasers
DACDAC
Pressure
5
For its mission, NNSA has built and operates the world’s three largest HED facilities:
NIF, OMEGA, and Z
99.999999% of the energy from a weapon is generated in the high energy density state
New 2009
Refurbished 2007
Performance Performance EnhancedEnhanced
2008 2008
6
NIF is Operational !
7
“The Next Really Cool Thing”by OP-ED Columnist Thomas L. Friedman
March 14, 2009 NY Times
• “Last Monday at 3 a.m., for the first time, all 192 lasers were fired at high energy precisely at once — no small feat …”
• 1.1 MJ in ultraviolet laser energy (3? ) with a shaped laser pulse on target
8
Ignition will be the start of a new scientific era for NNSA and the Nation
Ignition on NIF will be a defining moment for inertial confinement fusion energy
9
The National Ignition Campaign (NIC) is preparing for the 2010 ignition attempt on the NIF
Back-scattered light
X-ray emission thru LEH
FFLEX spectrometer (20-100 keV)
Laser-plasma instabilities can scatter light from capsule
Capsules must remain spherically symmetric as they implode
High-Z ball, or
implosion, viewed in emission
Four laser shocks used to heat capsule must be timed precisely
VISAR and/or SOP
Layered implosion with duddedfuel (THD) to test cryosystem
Diagnosticholes
10
The NIC is on an aggressive schedule
Drive temperature Trad96 beams
Symmetry, shock timing, and ablation rate technique validation
96 beams
Layered dudded fuel (THD) implosions,
192
bea
ms
DT Ignition Implosions
NIF Project CD4
192 beams
Layered THD
DT high yield
192 beams
Symmetry, shock timing, and ablation rate
NIC runs into FY12
11
On Jan 14-16, 2009 JASONs studied the NIC at the request of NNSA
CHARTER:Assess the readiness of the National Ignition Campaign (NIC) to
execute credible ignition experiments by end of 2010 including:– Target physics, including the specific ignition designs;– Target fabrication;– Diagnostics; – Facilities and associated technologies
Specific focus areas: • Progress including addressing issues in the 2005 JASON report• Will the NIC provide a reasonably optimal chance of success in the
first ignition experiments in 2010? • Is the plan for diagnostics deployment and preliminary experiments
adequate to support the 2010 goal? Will the set of initial diagnostics enable early experiments to guide next steps?
• Are the risks at an acceptable level and reasonably mitigated? After the first ignition experiment in 2010, how should the risk mitigation efforts change?
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JASON Summary
“While impressive progress has been made in the intervening period [since the 2005 JASON study]…substantial scientific challenges remain.”
- Extent of challenges will only be fully revealed once NIC experiments are underway.
- Diagnostics are planned for success and may not be sufficient to diagnose failures.
- JASON is not the appropriate body to review the NIC
- NIC is a scientific program [and must be managed differently from a project since it requires flexibility to adjust – perhaps radically - as things are learned]
NNSA is preparing its response
13
A technique to time the four shock waves in the NIF ignition target design has been demonstrated
14
An MIT-LLE collaboration has developed a Magnetic Recoil Spectrometer (MRS) to measure
fuel areal density
• The number of neutrons downscattered from the cold fuel in ignition tuning experiments is determined by the fuel areal density.
• An MRS has been deployed on OMEGA and measured the downscattered neutron spectrum in a cryogenic target implosion.
• This was used to infer the areal density.
15
The new Z provides increased capability.
26 MA (dynamic materials load)24 MA (radiation-producing load)
18 MApeak load current
459diagnostic lines of sight
variable pulse length, 100-300 nsminimalpulse shaping flexibility
+ 1% deviation+ 5% deviationpeak current reproducibility
After refurbishmentBefore refurbishment
Capability
• Extracted Ta data to a stress of 3.8 + 0.2 Mbar to complete first stewardship experiment on new Z in September 2008.
– Required very precise shaping of the current pulse, via a predictive capability using MHD and circuit codes, and a load geometry (the stripline load) to provide high uniformity and accuracy.
stripline load geometry
anode cathode
sample locations
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LANL model
top sample pair
Inferred stress-density of tantalum from first ZR stewardship experiment
• LANL provided Ta equation of state and samples. SNL designed, fielded, and analyzed the data.
• Red, green, and blue heavy (light) lines correspond to inferred isentrope (uncertainty) for top, middle, and bottom sample pairs, respectively. Black line is principal isentrope from LANL model.
17
High pressure measurements have been published in Science, and demonstrate greater capability than those published in UGT days
Data from one week of Z shots
Nuclear-driven data point
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Experiments have begun on the OMEGA Extended Performance (EP) Laser
• OMEGA EP was completed in April 2008 at the University of Rochester• Operation as an NNSA User Facility began in FY09
OMEGA EP significantly extends OMEGA’s research capabilities
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The first attempt of 22 keV high energy radiography showed superb spatial resolution at 22 keV
(926J, 90 ps, Jan 27, 2009)
10 µm grids20 µm grids
30 µm grids
80 µm grids
Ag micro-flag
22 keV x-rays
Inte
nsi
ty (
PS
L)
Line outs along the grid pattern10 µm grids
pxl
Au 50 µm thick substrate
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The propagation of a shock wave in Aluminum has been observed with a 17 keV backlighter
TCC
4 mm
backlighter target
80 ps backlighter
Al Sample
10 mm
Radiographic imager 4 ns UV drive
Radiograph of shock in Al @17.5 keVEP shot 4541 (Jan 29, 2009)
150 µm
UV drive: 907J, 4 ns long
Shock frontradiographyafter 4 ns through 800 µm thick Al
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LANSCE provides important contributions to the nuclear weapons program
• Nuclear cross-sections in support of Boost and Nuclear Forensics (Weapons Nuclear Research – WNR)
– New Time Projection Chamber capability supports Boost
• Proton Radiographic measurements – needed for PCF and Boost• Materials research – Data supports PCF and Boost• All of these require LANSCE for the next ten years
– LANSCE-R provides needed improvements for reliable LINAC operations
• Lujan Center–Materials and nuclear physics
• Weapons Nuclear Research (WNR)–Nuclear Physics –Neutron Irradiation
• Proton Radiography–Dynamic Materials science–Hydrodynamics
• Isotope Production Facility– Medical radioisotopes
• Ultra-Cold Neutron (UCN)–Fundamental Physics
8 mo/yr, 24/7, highly flexible beam delivery, simultaneous experiments - ~1200 user visits
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LANSCE: Proton Radiography is a key capability for developing
science-based prediction of weapons performance
Burn Front Position
02468
10
15 20 25 30 35 40
Time (microseconds)
Pos
ition
(cm
)
Detonation Failure Studies in PBX-9502
HE ScienceDynamic Materials Studies
Equation of state measurement with pRad and a powder Gun
6/16” Tin
3/16” Tin
5/16” Tin
7/16” Tin
8/16” Tin
Shock PhysicsMelt on release in Sn
300g Breech12' barrel
Catch tank
experimentalchamber
Proton Beam
2.7
2.8
2.9
3
3.1
3.2
3.3
3.4
3.5
0 0.5 1 1.5 2
Up (km/s)
Den
sity
(g/c
m3)
LASL Shock Hugoniot DataEmperical fitRadiographic velocity measurements
Pin velocity and radiographic density
Flyer Edge
Flyer shockTarget shock
Flyer velocitysabot
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Nuclear measurements on LANSCE are key to boost and forensics
• Pu fission neutron spectra and cross-sections are crucial factors for predicting and determining yield
• QMU and other national weapons initiatives required precise knowledge of these factors
• LLNL/LANL collaboration will measure– LLNL lead: Fission cross-sections to 1% accuracy using a Time-
Projection Chamber (TPC)– LANL lead: Fission neutron output spectra will be measured using
an advanced neutron detector array
Time-Projection Chamber for high-precision fission cross section measurements
• Final data analysis of 241Am(n,γ) (DANCE)
– > 50 keV some disagreement with ENDF/B-VII found
– New data evaluation eliminates discrepancy with Jezebel results
24stress (kbar)
0 10 20 30 40m
osa
ic S
pre
ad (d
egre
es)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Ambient
Shocked
Our NNSA funded universities are doing pioneering work: first dynamic x-ray diffraction at a light source
HPCAT
Advanced Photon Sourceat Argonne National Laboratory
gun-barrel
target chamber APS x-ray beam
detector
LiF(111) ; Mg doped LiF(100) ; Ultra-pure LiF(100)
Ambient Shocked
LiF(111) elastic Mg doped LiF(100) plastic
Density Change (percent)0 1 2 3 4 5La
ttice
Com
pres
sion
(per
cent
)
0.0
0.5
1.0
1.5
2.0
position
stress
25
DARHT 2nd Axis has exceeded all the goals and JASON predictions
Full Energy – 17 MeV
Full Current – 2 kA, 1.6 µs
Cells are all refurbished, installed and commissioned on schedule
Four pulses with more dose and smaller spot size than the project goals!!!
Technical Accomplishments
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• Metals subjected to HE loading have triangular wave shape
• Much of the research on shockwave induced damage (spall, ejecta) using shock techniques has been done with flat top waves.
• Time & Length scales in experiments are important:• Phase transitions occur in finite times• Loading / unloading rates affect processessuch as shock hardening & damage evolution (spallation / ejecta)
• Gun expts. are of similar timeframe to HE drive• Various Techniques can yield a Triangular-Shaped Shockwave Profile
PBX 9501
10-15 µsec0
0.5
1
1.5
2
2.5
3
0 0.5 1 1.5 2
Lon
gitu
dina
l str
ess
in P
MM
A (G
Pa)
Time (µs)
14.5 GPa 316L SS
Gas Launcher
A few µsec
Laser
A few nanosec
Triangular (‘Taylor’) spall is an important area of research to support development of predictive models
27
Recent Experiments on Bi-crystals Have Shown Dependence on Crystal Orientation
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SNL’s Z-Machine & mini-pulser: constant entropy compression experiments to probe basic material properties under ramp wave loading
High-P shots: unacceptable error in EOS [J. Appl. Phys. 99, 124901 (2006) ]Technique is very good at:
- distinguishing phase changes, elastic limit behavior - comparing response of multiple materials
Improved Explosive Models : Collaborative Isentropic Compression Experiment & Analyses
PBX 9501
HMX
Dirty binder
29
NNSA mission needs have driven the creation of environments that are ideal to study complex
HED plasmas and materials in extreme conditions
Mass Outflow
High Mach Number unstable flows
Jets
Rayleigh TaylorInstabilities
MHD, thermo-electric, and “anomalous” heatingShocks and radiation transport
Materials in the Extreme
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The broader importance of fundamental HEDPis recognized
National Academy/workshop reports
31
The NNSA/SC Joint Program in Laboratory High Energy Density Plasmas was created
to steward HEDLP within DOE
• 2004 Davidson report provided the starting point for the HEDP Interagency Task Force
• Key DOE finding: – Stewardship of HEDLP needs to be improved
• DOE has taken action to improve stewardship:– Joint Program in Laboratory HEDP announced
February 2007– Oversight of HEDLP now a joint NNSA/SC
responsibility– Joint Solicitation with Office of Science for FY09 Ø Large number of proposals – currently being
reviewed
• The DOE charged the Fusion Energy Science Advisory Committee (FESAC) to: “work with the HEDLP community to provide information to develop a scientific roadmap for the joint HEDLP program in the next decade”
• A FESAC subpanel was formed, chaired by R. Betti, Univ. of Rochester
32
NNSA and OFES are working on stewarding HED Physics
• We have establish a joint program on High Energy Density Laboratory Plasmas (HEDLP)
• We have planned a Research Needs Workshop for later this year
• We ran a joint program solicitation in 2009 and have received a significant number of proposals (~140)
• NNSA academic funding has been stabilized
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Conclusions and Path Forward
– The academic involvement in High Energy Density Laboratory Plasmas (HEDLP) is being stewarded through the Joint Program
– World-leading HED facilities, nuclear physics facilities, and facilities that support studies dynamic materials studies have been built and funded by NNSA
– Our program is making great progress towards ignition and other applications in HEDP materials, nuclear physics and dynamic materials science