Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

Magnetization Laser

Heating Compression

StatusoftheMagne.zedLinerIner.alFusionResearchProgram

intheUnitedStates

DanielSinarsSeniorManager,Radia.onandFusionPhysicsGroup

SandiaNa.onalLaboratoriesFusionPowerAssociatesMee.ng

Washington,D.C.December16-17,2015

TheU.S.ICFProgramispursuingthreemainapproachestofusionigni.ontomanagethescien.ficrisk

2

Magnetic direct drive is based on efficient use of large currents to create high pressures

33m

0

20

40

60

80

0 0.5 1 1.5 2 2.5

Marx generatorspulse-forming linesinsulator stack

pow

er (T

W)

time (µs)

20TW67TW

77TW

MBar

R

drivecurrent

I

Magne.callyDrivenImplosion

100MBarat26MAand1mm

Z today couples ~0.5 MJ out of 20 MJ stored to magnetized liner inertial fusion (MagLIF) target (0.1 MJ in DD fuel).

Magnetized Liner Inertial Fusion (MagLIF) relies on fuel preheat and magnetization to achieve fusion

S.A. Slutz et al., Phys Plasmas (2010); S.A. Slutz & R.A. Vesey, Phys Rev Lett (2012); A.B. Sefkow et al., Phys Plasmas (2014).

1cm

§  Inhibitsthermallossesfromfueltoliner§  Mayhelpstabilizelinerduringcompression§  Fusionproductsmagne.zed

Laserheatedfuel(2kJini.ally;6-10kJplanned)

AxialMagne.cField(10Tini.ally;30Tavailable)

§  Ini.alaveragefueltemperature150-200eV§  Reducescompressionrequirements(R0/Rf~25)§  Couplingoflasertoplasmainanimportantscienceissue

Magne.ccompressionoffuel(~100kJintofuel)§  ~70-100km/s,quasi-adiaba.cfuelcompression§  LowAspectliners(R/ΔΔR~6)arerobustto

hydrodynamic(MRT)instabili.es§  Significantlylowerpressure/density

Goal is to demonstrate scaling: Y (Bz0, Elaser, I) DD equivalent of 100 kJ DT yield possible on Z

Experimentshavedemonstratedthermalfusionwith>10122.45MeVneutronsfroma~70km/s,1.5mg/cm2implosion

§  Theini.alMagLIFexperimentsdemonstratedthatthereismerittotheideaofmagneto-iner.alfusion

§  Laserhea.ngofamagne.zedini.alplasmawithminimalhigh-Zmixiscri.cal§  Ini.alexperimentsused“uncondi.oned”beamsandthick(>3µµm)foilsand

deposi.onintothegaswaslowerthanexpected§  Lowenergydeposi.onandmixisborneoutbyseveraldifferentexperiments

onmul.plefacili.es§  ResearchoverthenextfiveyearsatZ,Omega,Omega-EP,andtheNIF

willaddress:§  Thephysicsoflaserpreheat§  Implosionandstagnatedfuelperformance§  Exploringfusionperformanceandscalingasafunc.onoflaserpreheat,

ini.alBfield,anddrive

§  Presentmodelingpredictsfusionyieldsof~100kJ(DT)arepossibleonZ5

LaserHea.ng• Elaser~2-6kJ@.53μm• TDT~0.2KeV• ωτ~2-5• ResearchonZ,ZBL,Omega,Omega-EP

Implosion/stagna.on• Vimp~70-100km/sec• PDT~5Gbar• Tion>5keV• ωτ~200(B~100MG)• ResearchonZ,Omega

We are taking a careful look at all stages of the target using multiple facilities and diagnostics

MagLIF target implosion history

Outerlinerboundary

Innerlinerboundary

Ini.alCondi.ons• Beliner• ρDT~1-4mg/cc• Bz0~10-30T(~0.1MG)

Basko et al. Nuclear Fusion 40, 59 (2000); P.F. Knapp et al., Phys. Plasmas (2015).

MagLIF Hot Spot ICF High B

h

R

Low B

§  Ini.al10-30Tfieldgreatlyamplifiedduringtheimplosionthroughfluxcompression

§  Toomuchfieldisinefficient—wanttostagnateonplasmapressure,notmagne.cpressure

Magne.za.on(BR)canbeusedtoreduceρρRrequirementsandreduceelectronheatlosses,lowerdensityalsoreducesbremsstrahlungradia.onlosses

§  Frac.onoftrappedtritons(orαα’s)afunc.onofBR

§  EffectssaturateatBR>0.6MG-cm

§  MeasurementstodatesuggestBRof0.4MG-cm

§  Focusedexperimentshavedemonstratedfluxcompressionw/B>1000T

Hea.ngthefuelpriortocompressioncanlowertradi.onalICFrequirementsonvelocityandfuelconvergence

Velocity (cm/µµs)

CR10

CR10 = Convergence Ratio (R0/Rf) needed to obtain 10 keV (ignition)

T0=150 eV

§  Laserhea.ngoffuel(6-10kJ)offersonewaytoreachpre-compressiontemperatureof~200eV

§  Detailedsimula.onssuggestwecanreachfusiontemperaturesatconvergenceR0/Rf~25

Simula.onwith:§  Constantvelocity§  Noradia.onloss§  Noconduc.vityloss

MagLIFhasaverydifferentcompressionmethodologyandstagna.onparametersthantradi.onalICF

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Metric X-rayDriveonNIF 100kJMagLIFonZDrive

Pressure ~140-160Mbar26MAat1mmis

100Mbar

Forcevs.RadiusGoesasR^2(decreasing)

Goesas1/R(increasing)

Peakvelocity 350-380km/s 70-100km/s

PeakIFAR13-15(highfoot)

to17-20 8.5

HotspotR0/Rf 35(highfoot)to45 25

VolumeChange43000x(high)to91000x 625x

FuelρρR >0.3g/cm^2 ~0.003g/cm^2LinerρρR n/a >0.3g/cm^2

BR n/a >0.5MG-cmBurn.me 0.15to0.2ns 1to2nsT_ion >4keV >4keV

Wehavespentmanyyearstes.ngourlinerimplosionmodeling,andhavemadesomeinteres.ngadvances

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Single-mode magneto-Rayleigh-

Taylor growth

High-resolution 2D modeling can capture early growth down to the ~50-micron scale

Magnetized MRT growth

Magnetized & dielectric-coated Be

(R0/Rf~17)

Experimental Data

Dielectric-coated Al liner implosion

Uncoated

Simulated Data

D.B. Sinars et al., Phys. Rev. Lett. (2010). R.D. McBride et al., Phys. Rev. Lett. (2012). T.J. Awe et al., Phys. Rev. Lett. (2013). K.J. Peterson et al., Phys. Rev. Lett. (2014). T.J. Awe et al., accepted for PRL.

Theini.alexperimentsused10T,2.5kJlaserenergy,anda~19MAcurrenttodriveaD2filled(0.7mg/cm3)Beliner

Bz Magnets

Target

Extended power feed

4.65 mm

7.5 mm

3 mm

D2 gas

0.465 mm

Anode

Cathode

2.5 to 3.5 µm

~2 ms rise time to 10 T

M.R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014). 11

0.5 kJ 2 kJ

0.45 mm

12

AnensembleofmeasurementsfromourfirstMagLIFexperimentsareconsistentwithamagne.zed,thermonuclearplasma!

X-rayImaging(plasmashape)

X-raySpectra(Te,mix)

Neutronspectra(Tion)

NuclearAc.va.on(yield)

DD DT

DT DTNeutronspectra(magne.za.on)

X-rayPower(dura.on)

MagLIF Z pinch M.R. Gomez et al. PRL (2014). P.F. Schmit et al., PRL (2014). P.F. Knapp et al., PoP (2015). M.R. Gomez et al., PoP (2015). S.B. Hansen et al., PoP (2015).

Lowerthanpredictedcouplingoflaserenergyduetoun-conditonedbeam(poorfoilburnthrough)?Zdatacanbemodeledbyassumingnomixand200-300Jinfuel

Simulation

Z2591 (2e12)

Z2584 (0.5e12) Z2613 (1e12)

2ns,2kJmainpulse

0.2ns,0.2kJ

Simulations with 200 J match not only the yield, but other parameters measured in the experiments (temperature, shape, BR, etc.)

mainpulse

HYDRA Simulations

A.B. Sefkow et al., Phys. Plasmas (2014).

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TargetanddriveparameterskeptconsistentwithMagLIFtargets:§  I~2.5x1014W/cm2(similarto850μmDPPsmoothedZBLpulse)–squarepulse§  Totalpreheatenergy:3.1kJ(c.f.2.5-4kJforZBL)§  Visibletargetlength:6.5mm(c.f.7.5-10mminMagLIF)§  ThickLEHwindow

WeareusingOMEGA-EPtoinves.gatepreheatatparametersrelevanttoMagLIF

Rexolite (CH) tube

6.5 mm

3 mm OMEGA-EP beam

3µm thick LEH

0.78 TW, 3.1 kJ 4 ns square pulse 750 µm DPP

PropagaRonin3gasdensiRestested(1stMagLIFexperimentsne=0.052-0.1nc)§  ne=0.055nc(10atmpressure,1.67mg/cm3)§  ne=0.077nc(14atmpressure,2.34mg/cm3)§  ne=0.10nc(18atmpressure,3.01mg/cm3)

OMEGA-EPexperimentsarehelpingusunderstandwhenandhowmuchwecantrustourmodeling§  ExperimentsinD2showthedensity(ne=0.1nc),

increasesLPI,affectsenergydeposiRon

§  IncreasedLPIaresultofthickLEHwindowdisassembly–usingaprepulseaffectsthis

§  ForcondiRonswhereinverseBremmstrahlungdominates,simulaRonscanmatchexperiments.ExtrapolaRontoZ:mulR-kJheaRngpossible

§  Developingthin-windowcryotargetsshouldimprovetargetpreheat,reduceLPI

Distance (mm)

ne~0.1nc

Propagation in doped D2 3.1 kJ delivered to targets

Time gated emission images

ne~0.077nc

ne~0.1nc, pulseshaped

Experiments in pure Ar: ne=0.047nc, 1 µm thick LEH, I~2.5x1014 W/cm2

Adesignforlaser-drivenMagLIFonOMEGAhasbeendevelopedandwillbedemonstratedinthenext2years

§  Experimentsin2015haveestablishedthatwecancouplethelasertothetargetandheatitallthewaythroughto>100eV

§  Wehaveachievedcylindricalcompressionatthedesiredimplosionvelocity,andrecentexperimentshaveop.mizedthecompressionlengthover>0.7mm

§  1stintegratedtestsonOMEGAtostartonJune1,2016

Parylene-N Target Outer diameter: 600 µµm D2 fill density: 1 – 2.1 mg/cc Shell thickness: 30 µµm Preheat temperature: ≥≥ 100 eV Compressed length: 600 – 700 µµm

Ring 3 only

520±19 µm ~180 km/s (Ring 4)

Fill tube Pressure transducer

Target support

Preheat beam from P9 200 µµm phase plate Up to 200 J in 2.5 ns

40 compression beams SG2 phase plates

Up to 12 kJ in 2.5 ns

Ring 3 Rings 4 Ring 3

MIFEDS coils B ∼∼ 10 T

1 mm

X-ray image of compression

Itmaybepossibletoachieve~100kJyieldsonZ.Achievingalphahea.ngandigni.onmaybepossibleonafuturefacility.AcryogenicDTlayercouldenableupto~1GJyield.

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AnintermediateregimeexistswhereintheBzfieldis•  strongenoughtoreduceconducRonlosses,but•  weakenoughnottoinhibittheαdeflagraRonwave

S.A. Slutz and R.A. Vesey, Phys Rev Lett (2012); A.B. Sefkow et al., Phys Plasmas (2014).

Experimentshavedemonstratedthermalfusionwith>10122.45MeVneutronsfroma~70km/s,1.5mg/cm2implosion

§  Theini.alMagLIFexperimentsdemonstratedthatthereismerittotheideaofmagneto-iner.alfusion

§  Laserhea.ngofamagne.zedini.alplasmawithminimalhigh-Zmixiscri.cal§  Ini.alexperimentsused“uncondi.oned”beamsandthick(>3µµm)foilsand

deposi.onintothegaswaslowerthanexpected§  Lowenergydeposi.onandmixisborneoutbyseveraldifferentexperiments

onmul.plefacili.es§  ResearchoverthenextfiveyearsatZ,Omega,Omega-EP,andtheNIF

willaddress:§  Thephysicsoflaserpreheat§  Implosionandstagnatedfuelperformance§  Exploringfusionperformanceandscalingasafunc.onoflaserpreheat,

ini.alBfield,anddrive

§  Presentmodelingpredictsfusionyieldsof~100kJ(DT)arepossibleonZ18

19

Wearecurrentlyexploringtargetdesignsandpulsedpowerarchitecturesthatmaybeonthepathto0.5-1GJyieldsandthatalsomeettheneedsofthesciencecampaigns

“Z800” •  800 TW •  52 Meter diameter •  61 MA •  130 MJ Stored Energy

Fusion Yield 0.5-1 GJ? Burning plasmas

“Z300” •  300 TW •  35 Meter diameter •  47 MA •  47 MJ Stored Energy

Yield = Etarget? (About 3-4 MJ) αα-dominated plasmas

Z •  80 TW •  33 Meter diameter •  26 MA •  22 MJ Stored Energy

Yield = Efuel? (~100kJDT eq) Physics Basis for Z300

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Wehavesuccessfullyimplemented10-30Taxialfieldsoveraseveralcm3volumeandseveralmsforMagLIF

Capacitor bank system on Z 900 kJ, 8 mF, 15 kV (Feb. 2013)

Example MagLIF coil assembly with copper windings visible

Bz Magnets

Liner (~1 cm height) Extended

power feed

10 Tesla

Time to peak field = 3.49 ms Allows field to diffuse through the liner without deformation

10 T configuration

Cross section of coil showing Cu wire, Torlon housing, and Zylon/epoxy reinforcement

D.C. Rovang, D. Lamppa et al., Rev. Sci. Instrum. (2014).

TheZ-BeamletlaseratSandia*isbeingusedtoradiographlinertargetsandheatfusionfuel

Z-Beamlet and Z-Petawatt lasers

Z facility Z-Beamlet High Bay

Z-Beamlet (ZBL) is routinely used to deliver ~ 2.4 kJ of 2ω light in 2 pulses for backlighting experiments on Z In 2014 we added bandwidth to the laser; can now deliver ~4.5 kJ of 2ω in a 4 ns pulse. It should be possible to reach 6-10 kJ of laser energy (e.g., as on the NIF) An advantage of laser heating is that it can be studied and optimized without using Z

* P. K. Rambo et al., Applied Optics 44, 2421 (2005).

Typical MagLIF initial fuel densities correspond to 0.10 to 0.30 x critical density for 2ω