The Development of Indirect Drive ICF and theCountdown to Ignition Experiments on the NIF

Maxwell Prize AddressAPS Division of Plasma Physics Meeting

November 15, 2007

John LindlNIF and Photon Science Directorate Chief Scientist

Lawrence Livermore National Laboratory

Work performed under the auspices of the U.S. Department of Energy byLawrence Livermore National Laboratory under Contract DE-AC52-07NA27344

The NIF ignition experiments will be the culminationof five decades of development which started withthe invention of the laser in 1960

• Ted Maiman demonstrated the first laser in 1960

• John Nuckolls 1972 Nature paper spelled out the essential requirementsfor high gain laser driven ICF

• Indirect drive experiments started at Livermore in the mid-1970’s• Dramatic advances in computations, lasers, diagnostics, and target

fabrication over the past 3 decades laid the groundwork for NIF and theNational Ignition Campaign (NIC)

• We are designing precision experimental campaigns for hohlraumenergetics, shock strengths and times, implosion velocity and ablatedmass, and symmetry, which will take 100-200 shots leading up to the firstignition attempts

• Targets near 1 MJ of laser energy have a credible chance for ignition inearly NIF operations

• The initial ignition experiments only scratch the surface of NIF’s potential

Inertial ConfinementFusion uses direct orindirect drive to coupledriver energy to the fuelcapsule

Spherical ablation withpulse shaping results in arocket-like implosion ofnear Fermi-degenerate fuel

Spherical collapse of theshell produces a centralhot spot surrounded bycold, dense main fuel

Indirect Drive

Hot spot(10 keV)

Cold, densemain fuel(200-1000 g/cm3)

Low-zAblator forEfficientabsorption

CryogenicFuel forEfficientcompression

There are two principal approaches to compression in Inertial Confinement Fusion

Direct Drive

DTgas

2.5 mm 0.1

mm

10mm

To illustrate the physics of ICF ignition, we compare aNIF capsule and a possible future high yield capsule

High yield capsule

NIF capsule

Radiation temperature = 300 eV 210 eVImplosion velocity = 4 x 107 cm/sec 3 x 107 cm/secCapsule absorbed energy = 0.15 MJ 2.0 MJCapsule yield ~ 15 MJ ~ 1000 MJ

CH + 0.25% Br + 5%O

DT solid (0.2 mg)

DT gas 0.3 mg/cc

1.11 mm

0.95

0.87

3.25mm

3.0

2.75

Be

DT solid(7.2 mg)

DT gas0.3 mg/cm3

Ignition is defined as the point at which α−particledeposition sustains the burn with no additionalinput of energy

0.2-MJNIF capsule(yield ~20 MJ)

2.0 MJcapsule (yield~1000 MJ)

Density and temperatureprofiles at ignition

ρr (g/cm2)

Ion

tem

pera

ture

(keV

)

12

8

4

0.2 0.4 0.6 0.8 1.0

Burn propagation after ignitiondepends only on fuel ρR

ρr (g/cm2)

Ion

tem

pera

ture

(keV

) 103

102

101

100

10-10 1 2 3

About 15 kJ of energy is coupled to the fuel for compression and ignition of the200 kJ NIF sized targetAt 1 MJ of yield, 200 kJ of α-particle energy is coupled to the fuel and it is well intothe ignition region - definition of ignition adopted by 1996 NRC review of NIFIn ITER with a Q=10, α-deposition is twice the external power needed to sustain theplasma

α-particlerange at10 keV

timeρ

Ti

102

103

101 Den

sity

(g/c

m3 )

• Over 3 decades of experiments on Nova, Omega and other facilitieshave provided an extensive data base to develop confidence in thenumerical codes

• Benchmarked numerical simulations with radiation-hydrodynamicscodes provide a first principles description of x-ray target performance(Laser-plasma interactions are treated separately with codes which arenow becoming predictive for NIF-relevant plasmas)

• “The Halite/Centurion experiments using nuclear explosives havedemonstrated excellent performance, putting to rest fundamentalquestions about the basic feasibility to achieve high gain” from 1990NRC review of ICF

Energy

Power

NIF Ignition

Nova, Omega

Halite/Centurion

Why do we believe that ignition will work on NIF?

The first laser was demonstrated by TheodoreMaiman in Malibu, CA, in May 1960

John Nuckolls and John Emmett were central tothe development of the LLNL ICF Program

John Emmett,who came toLLNL in 1972was the drivingforce behind thedevelopment ofthe LLNL laserprogram

John Nuckolls’vision of smallthermonuclearexplosions, laidout in his seminal1972 Naturepaper, providedthe motivation foran aggressive ICFProgram

Disk Amplifier Prototype from the mid 1970’s

Would you hire these people?

Laser Programs1978 ManpowerBook

George Zimmerman

John Lindl

Mike Campbell

Ed Moses did not come to Livermore until the 1980’sbut he would have fit right in during the 1970’s

Laser Programs1978 ManpowerBook

George Zimmerman

John Lindl

Mike Campbell

Ed Moses

• 1970’s: Radiation driven target designs provided a path forward for high gainICF with relaxed laser beam quality and hydrodynamic instability comparedto direct drive

• 1976: first laser driven indirect drive experiment in 1976 on the Cyclops laser

The first steps leading to indirect drive ignitionwith lasers took place in the mid 1970’s

—Cyclops was developed as a prototype beamline for Shiva

The 20 beam 10 kJ 1.06 µm Shiva laser was amajor step forward in the scale and complexity ofhigh energy laser systems

Shiva target areaShiva laser bay

1979-1981: Shiva and Argus experiments show limits to radiationtemperature from LPI and a path to TR>200 eV using frequency convertedlight (2ω and 3ω)

Experiments on the Argus and Shiva lasersprovided key results on achievable hohlraumtemperatures

Hot electron fractions approached50% in 1ω hohlraums on Shiva

Shorter laser wavelengths candramatically reduce hot electronsfor a given laser energy into ahohlraum

08-00-0594-2502.pub

100

10–1

10–2

10–3

10–4

fR = 1.0 –!tc IL dt/Etotal

2 " 10–4 2 " 10–3 2 " 10–2

2 " 6

2 " 32 " 2

2 " 1

3 " 6

4 " 6

Cairn hohlraum scale size(scale 1 = 500-µm

diam " 800 µm long)

Incident energy (kJ)

3 " 3

3 " 1.5

2 " 10–1 1

1% at Tr = 130 eV30-50% at Tr ~160-170 eV

Flue

nce

(keV

/keV

) 1012

1010

108

Energy (keV)

Hot ElectronFraction

With Nova, the ICF program brought together advancesin laser performance, precision diagnostics, andadvanced modeling tools needed to establish therequirements for Ignition.

From 1984 to 1999, the 10 beam, 30 kJ, 0.35 µm Novalaser was the central facility for indirect drive ICF

00

1 2Total energy (MJ)

200

400

Pow

er (T

W)

plasmainstabilities

hydroinstability

symmetryHigh volRfinal

Rolarge

large R/DR

High Pr, Tr, ILHohlraum physics acceptable below about 300 eV

Plasma physics issues constrain the hohlraumtemperature and hydrodynamic instabilitiesestablish the minimum required temperature

“Bird’s beak” plot from 1990

NIF designcapabilities

Hydrodynamicinstabilitiesdetermine theminimumtemperaturerequirement

• 1985-1990: Nova experiments demonstrated key target physics requirementsfor laser driven high gain (pulse shaping, symmetry control, Rayleigh-Taylorstabilization by radiation ablation, TR>200 eV with 3ω light

• 1990: 300 eV hohlraum temperature demonstrated on Nova led to a reducedscale ignition facility from the 5-10 MJ LMF to the 1-2 MJ NIF asrecommended by the 1990 NRC review of ICF

• 1990’s Demonstration of precision control of laser driven hohlraums asrequired for ignition (Nova Technical Contract from 1990 and 1996 NRCreviews of ICF)

Experiments on the Nova laser demonstratedkey target physics results needed for ignition

Scaling of peak drive temperature300

250

200

150150 200 250 300

Experimental peak Tr (eV)

Lasn

ex p

eak

Tr (e

V)

Hohlraum Length (µm)

Advanced diagnostics have been central tomeasuring the phenomena critical tounderstanding NIF

1.6 ns

1.9 ns

2.2 ns

2.5 ns

time

time

Sequence of x-ray backlitimages of imploding capsuleGated MCP x-ray imager

Pinholes MCP +film pack

Gatingelectronics

1 m

MCP gated imagers were operated between 100 eVand 10 keV with 5-50 µm, 30 -300 ps resolution

300µm

Face-on: Streaked

08-00-0593-1818B

The measured growth of ablative hydrodynamicinstabilities in ICF agrees with numerical models

3-D 2-DTime (ns)

Growth of Harmonics vs time

Interactionbeam

L=2 mm and longerCH gas fill

produces uniformne/ncr=6%

3w TransmittedBeam Diagnostic

Full-ApertureBackscatter Station

(FABS)

Near Backscatter Imager(NBI)

0

1

2

3

4

0 500 1000

Time (ps)

Elec

tron

Tem

pera

ture

(keV

)

Te

Ti

Plasma temperatures measured with Thomsonscattering agree well with simulations

0

0.05

0.1

0.15

-1.5 -1 -0.5 0 0.5 1 1.5

Interaction Beam Path (mm)

n e/n

cr

A uniform 6%ncr plateau is produced between0.5 and 1.0 ns

Froula et al., Phys. Plasmas 13(5) (2006)

t=0.5 ns

t=1.0 ns

Recently, we have been able to produce well characterizedNIF-like plasmas on the Omega laser

Calculations of these Omega experiments provideevidence of a significant step towards meeting the

grand-challenge of predictive modeling of LPI with pf3d

• PS instantly reduces the contrast, suppressing theamplification from intense speckles

•The pF3D calculations took about 1 million CPU hours

DataNO PS

DataPS

pF3d PS:

D. Froula et al. to be published

pF3d no PS:

Beam power (GW)

SBS(

%)

CPP

150 µm

CPP+PS

Best Focus

Divol TI1-5ThursdayFroula NO6-13Wednesday

The scale of ignition experiments isdetermined by the limits to compression

200

100

10

1

0.2

Compression (X liquid density)102 103 104 105

50050

5

0.5

Capsuleenergy (KJ)

NIF

Relaxed pressure and

stability requirements

Ther

mon

ucle

ar e

nerg

yCa

psul

e ab

sorb

ed e

nerg

y

Capsule Energy Gain Plotted vs Compression • Pressure is limited toP(Max)~100 Mbar by LaserPlasma Interaction (LPI)effects

• Given the pressure limits,hydrodynamic instabilitieslimit implosion velocities to

!

Vimp

< 4"107cm/sec

and this limits themaximum compression

• Symmetry and pulseshaping must beaccurately controlled toapproach the maximumcompression

NIF will provide a qualitative advance in ICF capabilitywith >50X more energy and far greater precision andflexibilty than any previous high energy laser facility

Cluster 4 Cluster 2 Cluster 1

End view of NIFCluster 3

Upper quad

Lower quad

Bundle

Cluster 1Cluster 4

Cluster 3Cluster 2

Top view of targetchamber (upper quads)

NIF is a 192 beam laser organized into “clusters”,“bundles” and “quads”

The NIF Project is over 94% complete and 15 of the 241 µm laser bundles (120 beams) have beenperformance qualified

(single beam)

Hohlraum Wall: – U or U0.75Au0.25

Laser Beams(24 quads through eachLEH arranged toilluminate two rings onthe hohlraum wall)

Laser Entrance Hole(LEH) with window

Hohlraum Fill – He0,8H0.2 at 0.9 mg/cm3

10.8mm

Capsule fill tube

Graded-doped BeCapsule (CH andDiamond are alternates)

Solid DTfuel layer

The NIF point design has a graded-doped, berylliumcapsule in a hohlraum driven at 285 eV

Cryo-coolingRing

Aluminum assembly sleeve

°°°

°

Precision target fabrication and assemblytechniques being developed for the NIF meetthe ignition target requirements

Nikroo YO5-4Friday

Forsman YO5-3Friday

Initialoperations

TR(eV)

225

250270

300

Max allowed hot spotdegradation fraction

ε = 0.2 0.3 0.4

Experimentallower limit

for 1%scatter

Tanglineartheory10%

scattering

Ignition point design optimization must balanceLPI effects, laser performance impacts, andcapsule robustness

Ignition point design optimization must balanceLPI effects, laser performance impacts, andcapsule robustness

DesignOptimum forinitial ignitionexperiments

SSD and Polarization smoothingto be incorporated on NIFraises this threshold

Initialoperations

TR(eV)

225

250

270300

Max allowed hot spotdegradation fraction

ε = 0.2 0.3 0.4

Experimentallower limit

for 1%scatter

Tanglineartheory10%

scattering

285 eVPoint

design

Laser beam propagationin the hohlraum

X-ray generationand symmetryof the radiationflux onto thecapsule

Hydrodynamicinstabilities asthe ignitioncapsule implodes

Detailed calculations of NIF ignition targets present anumber of computational grand challenge problems

°°°

°

•Integrated hohlraum and capsule calculations - low spatial frequency perturbations (l=8 or less) — Hohlraum radiation flux asymmetry — Pointing errors — Power Imbalance — Capsule misplacement in the hohlraum

— Hohlraum misalignment in the chamber— Missing beams or other off normal operation— Holes in the hohlraum or other inherently 3D structure

• Capsule only calculations - intermediate to high spatialfrequency perturbations (l=10 to 1000) — DT ice roughness — Ablator roughness — Ablator microstructure• Single Beam - Very high spatial frequency perturbations — laser wavelength and laser frequency scale features in the

incident beam and in laser plasma interaction in the hohlraum

The Advanced Simulation Capability (ASC)computers are essential for a wide variety of 3Deffects which impact NIF ignition targets

Resolving laser wavelength scale phenomena inthe propagation of a laser beam in an ignition scaleplasma is a grand challenge problem.

9.2mm

°°°

°

letterbox” simulationscapture the essentialphysics for “near 2D”situations, like a NIFhohlraum, “

A letterbox run for 10’sof picoseconds using thecode pF3D requires 8Terabytes of memory and~ 2.5M cpu-hours on the8000 processor Atlasmachine or ~ 15M cpu-hours on 32,000processors of the128,000 processor BG/Lmachine

HinkelTI1-4 Thursday

Optimized 2D symmetry calculations meet the pointdesign requirements

Be capsule fuel region at ignition

80µ

The imploded fuel coreshows very little residualangular variation from theNIF multi-cone geometry Callahan

UO3-1 Friday

Calculations with Hydra of the 300 eV point designshow very little intrinsic 3D azimuthal asymmetry

Cross section perpendicular to the

hohlraum axis at ignition

80µ

A 3D hohlraum calculationcapable of resolving l=8radiation asymmetry requiresabout 0.2M CPU hours

3D calculations to assessthe effects of powerimbalance, pointing errors,capsule placement errors, etcare in progress

Jones YO6-8Friday

The ignition point design capsule is subject tohydrodynamic instability over a wide range ofspatial scales

Outer surface of the Be ablator -up to about mode 120 during theacceleration process

Inner surface of the DT fuel - up toabout mode 30 during decelerationto ignition conditions

Interface between Be and DT - upto about mode 1000 duringacceleration

ignition point design capsule

Detailed 3D effects of capsule surface roughnessare evaluated using HYDRA calculations

• 3D radiation asymmetry isobtained from integratedhohlraum simulations

• Nominal “at spec” capsulefabrication perturbationsare applied on the DT iceand the ablator

Ignition Time140 ps BeforeIgnition Time

Ablator/DTinterface

Hohlraumaxis

Stagnationshock

400 g/cc density isosurface (different scale)

60 g/cc density isosurface

A full sphere coveringmodes 1-30 or an octantcovering modes 4-120 requires about 170 millionzones and ~ 4 million cpuhours on 4000 processors ofthe 10,000 processor 100TFLOP purple machine

Hydrodynamic instabilities at the capsule ablator-fuelinterface are a particularly challenging problem

Calculationsresolve instabilitygrowth in 3D, up tomode 1000, at theBe/DT interface

Benchmarkcalculations for a4.5-9 degree wedgeusing the HYDRACode require 44-176 million zonesand 1-4 million CPUhours on 1000-4000processors on the10,000 processor,100 TFLOP purpleMachine Hammel PO6-3

Wednesday

The point design capsule of copper doped Bedriven at 285 eV has been specified in detail

(Cu doped Be shell for 285eV, 1.3 MJ)

Parameter Be(285) "current best calc"

Absorbed energy (kJ) 203Laser energy (kJ)(includes ~8% backscatter)

1300

Coupling efficiency 0.156

Yield (MJ) 19.9Fuel velocity (107 cm/sec) 3.68Peak rhoR (g/cm2) 1.85Adiabat (P/PFD at 1000g/cc) 1.46Fuel mass (mg) 0.238Ablator mass (mg) 4.54Ablator mass remaining (mg) 0.212Fuel kinetic energy (kJ) 16.1

A CH capsule at 300eV and 1.3 MJ is the principalalternate to Be at 285 eV

•Post-processed hohlraumsimulations at 300 eVindicate LPI equivalent to orbetter than Be at 285eV•Amorphous material withno crystal structure issues•Large data base from Novaand Omega•Less efficient ablator but at1.3 MJ (&300eV), this targetlooks attractively robust.More work in progress.•Transparency makes cryolayer easier to characterizebut low thermal conductivitymakes layer formation in thehohlraum more challenging

1110 µm

10151000

965955

875

YieldEabs

Implosion velocityFuel mass

Ablator mass

CH(300)17.6 MJ150 kJ3.85 x 107

cm/s 0.21 mg2.3 mg

We are also evaluating a nanocrystalline diamondablator option at 270 eV and 1.3 MJ

YieldEabs

Implosion velocityFuel mass

Ablator mass

24.7 MJ260 kJ3.58 x 107 cm/s0.27 mg5.26 mg

Diamond(270)

3.51 g/cc75 µmthickDT 61 µmthick

1.3 MJ, 270eV design

• Higher density: diamond absorbsenergy at larger radius. Equivalentto 10 - 20% more laser energy.

• Ablator surface is very smooth.Can tolerate 20x the measuredsurface roughness.

• LPI analysis indicates 270 eVdiamond hohlraum has less riskthan Be hohlraum at 285eV

• Complex material propertiesduring pulse shaping: Stays solidafter 1st shock, melts with 2ndshock (Be melts with 1st)

1300

Ho TI1-3 Thursday

Assessment of ignition targets utilizes computercalculations, coupled to planned precision targetphysics campaigns

Our key question is not “How well can the codes predict theignition target a-priori?”, but instead “Will the uncertainties and

variability that remain after our tuning programs be acceptable?”This is a key focus of our preparations for ignition experiments

• We are designing experimental campaigns for hohlraum energetics, shockstrengths and times, implosion velocity and ablated mass, and symmetry,which will take 100-200 shots leading up to the first ignition attempts

• Most physics uncertainties will be normalized out with these “optimization”experiments (Residual physics uncertainties for these items are set by howaccurately we can do the experiments - the point design specs includeestimates for the achievable accuracy)

• Specifications on target fabrication and laser performance are set to achievethe required precision and reproducibility.

• Uncertainty in some physics issues such as DT thermal conduction andalpha particle deposition in Fermi degenerate DT will remain after theseexperiments

Drive temperature Trad(Target scale, energy and focal spot size)96 beams

Demonstrate symmetry, shock timing andablation rate techniques at NIF scale96 beams

Point design symmetry, shocktiming, and ablation rate

Commission 96more beams

Hohlraum coupling with 192 beams forbaseline target scale, energy & Trad

192

beam

s

Ignition campaign

Integratedphysicsexperiments

The National Ignition Campaign is focused onpreparing for the first ignition experiments in 2010

The 23.5º and 30ºbeams heat the waist ofthe hohlraum The 50º beams and 44º

beams heat the hohlraumnear the LaserEntrance hole

The 96 beam campaign will utilize the 30º and 50ºbeams to emulate the ignition target

°°°

°

The 96 beam emulators are scaled to preservehohlraum energy density and per beam intensity

300 eV1 MJ,192beams)

Rcap = 1 mm

Rhohl=2.55 mm

RLEH=1.275 mm

Rcap = 0.7 mm

Rhohl=1.785 mm

RLEH=1.275 mm

cm

cm

96-beamEmulatorat 70%scale

We use full-sizephase plates,so the LEH isnot scaled.

Meezan YP8-38Friday

We test various TRADignition designs bychanging only thelaser pulse-shape.

The 96-beam scaled experiments closely matchthe ignition plasma conditions.

96-beam

Ignition(scaled)

96-beam

Ignition(scaled)

ne/nc (max = 0.3) at peak power

“Keyhole” targets to meet the shock timingrequirements are one of the optimization targetswhich precede ignition experiments

°°°

°

Surrogate Capsule andPedestal support

Visarline ofsight

Robey YO6-15 FridayBoehly CO5-8 Monday

Accurate pulse shaping is a key to “1D”capsule performance

VISAR measures shockFront doppler shift

Cold D2

1st shock

3rd

2nd

Hohlraum

interfaceVISAR Image of

3-shocks

• Jump in fringe shift gives shock arrival

• Fringe position gives shock velocity

Pulse shape for Be at 1.3 MJand 285 eV

NIF’s pulse shaping system wasdesigned specifically to meet theserequirements

Timing of first3 shocks fromvisar (50 ps)

Timing of 4th rise fromshock collision opticalemission (100ps)

Hohlraum drivesymmetry includingeffects of LPI and laservariability for longwavelength 3Dperformance

Pulse shaping andcapsule parametersfor “1D” performance

We are doing multivariable sensitivity studies toassess the margin and robustness of ignitiontarget designs

°°°

°

Hydrodynamicinstability forshorter wavelength3D performance

Salmonson TI1-2Thursday

We have identified 34 pulse shaping and capsuleparameters that impact 1Dcapsule performance

Time

Radi

atio

nTe

mpe

ratu

re

Shock Timing ParametersShock Levels (4)Shock Times (4)Steepness of Final Rise (1)

Capsule ParametersLayer Thickness (7)Material Composition (8)Impurity Concentration (10)

Dens

ity

Radius

In order to vary all parameters simultaneously, weincorporate a distribution for each

Top-Hat distribution

0 1-1x spec

Normal distribution

0 1-1x spec

prob

abilit

y

For complex physical processessuch as shock timing and levels

that will likely vary normally.

For fabrication specs such ascapsule dimensions that can be

measured and rejected.

We use ensembles of simulations to estimate theprobability of ignition

Yield(MJ)

Be at 1.3MJ and 285 eV

95% have yield > 2 MJ

Results of 10,000 runs varying all 341D parameters randomly within theirrespective distributions

Statistical ensembles of 2D simulations includeperturbations on all capsule surfaces

•All 1D parameters (dimensions,compositions, densities, drive parameters)sampled statistically•Roughness for all 2D surfaces set “at spec,”phases varied randomly

Be layer roughness

100.0

10.0

1.0Sqrt

(Pow

er) =

rms

roug

hnes

s (n

m)

1.0 2.0 5.0 10.0 20.0Modes

2D calculations provide an assessment of theimpact of non-spherical effects

~85% above 1 MJ

~2/3 above 12 MJ

Results of 360 2D simulations (A statistical sample of 60 1Dcapsules with 6 random number seeds in 2D for each 1D point)

The 285 eV point design has a credible chancefor ignition in early NIF operations….

Energy Margin = Target Energy divided bythe minimum energy required for ignition

Gain

Energy Margin M

!

G

!

G +"RMS

!

G "#RMS

Point design capsule hasa margin of 4.8 with all 1Dparameters nominal andno 3D effects

5

10

Ignition achieved fortargets with Margin >1

00.5 1 2 3 4 5

Median V,entropy3D at specMargin 1.5

15

1D2D

Haan BP8-34 MondayClark TI1-1 Thursday

Ultimately, yields well in excess of 100 MJ maybe possible on NIF

Expected NIF performance at 2ωwith optimized conversioncrystals and lenses

Potential NIF performance at 2ω based on stored 1ω energy

Expected NIFperformance at 3ω

Tr(eV)

Yields versus laser energy for NIF geometry hohlraums

Band isuncertainty in

hohlraumperformance

2010-2011experiments

200 eV

210 eV

225 eV

250 eV

270 eV

300 eV

Laser energy (MJ)

Yiel

d (M

J)

Double shell indirect drive targets are apossible alternate for ignition

05-00-0696-1321

• Non-cryogenic

• Low radiationtemperature relaxesLPI effects

• Fabrication to controlmix is a majorchallenge

•Inherently limited torelatively low gainbecause most of thecompressed mass isinert

Low-z ablator(e.g. Be or CH)

High-z shell(e.g. Au/Cu)

Graded densitymaterial to controlhydro instabilityduring collision(e.g variable densityCu foam)

DT fuel

NIF can explore direct drive or fast ignitionas alternate approaches to ignition

05-00-0696-1321

• Separate compression and ignition• Potentially highest gain• Short pulse physics is major issue

Fast IgnitionPolar Direct Drive

• Direct Drive in the Indirect Drive Geometry• Higher coupling efficiency than indirect drive• Beam smoothing and implosion symmetry are major challenges

The NIF ignition experiments will be the culminationof five decades of development which started withthe invention of the laser in 1960

• Dramatic advances in computations, lasers, diagnostics, and targetfabrication over the past 3 decades have laid the groundwork for NIF andthe National Ignition Campaign (NIC)

• Experiments for hohlraum energetics, shock strengths and times,implosion velocity and ablated mass, and symmetry, will normalize outmost remaining physics uncertainties

• Targets near 1 MJ of laser energy have a credible chance for ignition inearly NIF operations …..when the required precision of targetexperiments, laser performance, and target fabrication is achieved

• The initial ignition experiments only scratch the surface of NIF’s potential

Ignition is a grand challenge undertaking. It is likely to take a fewyears to achieve the required level of precision and understandingof the physics and technology needed for success.