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?

12

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

16

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

18

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

19

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

20

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

21

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

22

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

28

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

30

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

33

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