Photos placed in horizontal position with even amount of white space

between photos and header

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.

Plans for addressing MagLIF hypotheses in 2017 and beyond

Patrick Knapp representing the MagLIF teamNISP Working GroupWashington D.C.September 13, 2016

2

As always, many people contributed to this talk….Matt Gomez1, Chris Jennings1, Stephanie Hansen1, Steve Slutz1, Kelly Hahn1, Eric Harding1, Paul Schmit1, Brian Hutsel1, Dean Rovang1, Gordon Chandler1, Edward Norris7, Adam Sefkow6, Dan Sinars1, Kyle Peterson1, Mike Cuneo1, Ryan McBride1, Tom Awe1, Matt Martin1, Dave Ampleford1, Carlos Ruiz1, Gary Cooper1, Bill Stygar1, Mark Savage1, Mark Herrmann3, Gregory Rochau1, John Porter1, Ian Smith1, Matthias Geisel1, Patrick Rambo1, Jens Schwarz1, Mike Campbell6, Brent Blue3, Kurt Tomlinson2, Diana Schroen2, Robert Stamm4, Ray Leeper5, Charlie Nakleh5

… And many many more1Sandia National Laboratories, Albuquerque, NM2General Atomics, San Diego, CA3Lawrence Livermore National Laboratory, Livermore, CA4Raytheon Ktech, Albuquerque, NM5Los Alamos National Laboratory, Los Alamos, NM6 Laboratory of Laser Energetics, Rochester, NY7 Missouri Univ. of Science and Technology, Rolla, MO

Thebroadthemeforaddressingexistinghypothesesisenergybalance

§ Howmuchenergyisabsorbed§ Howmuchenergyisscattered§ Howmuchmixisgenerated,

wheredoesitgo

4

Radial Posi tion [mm]

AxialPosition[m

m]

z2839: Ar Imager

−2 −1 0 1 2−10

−9

−8

−7

−6

−5

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−3

−2

−1

0

0

1000

2000

3000

4000

5000

6000

7000

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§ Whatisthehot-spotpressure,mass,volume

§ Whatisthedrivepressurenearstagnation

§ Howwellisthelinerconfiningthefuel

§ Isthereresidualkineticenergy

§ Whatistheradiationlossinflight§ Howeffectiveismagneticinsulation§ Whataretheend-losses

Detailed accounting of the energy in the system at each phase is critical to distinguish

between hypotheses

ElaserPdV PdV

LradLcond

Lend

Thebroadthemeforaddressingexistinghypothesesisenergybalance

§ Howmuchenergyisabsorbed§ Howmuchenergyisscattered§ Howmuchmixisgenerated,

wheredoesitgo

5

Radial Posi tion [mm]

AxialPosition[m

m]

z2839: Ar Imager

−2 −1 0 1 2−10

−9

−8

−7

−6

−5

−4

−3

−2

−1

0

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

§ Whatisthehot-spotpressure,mass,volume

§ Whatisthedrivepressurenearstagnation

§ Howwellisthelinerconfiningthefuel

§ Whatistheradiationlossinflight§ Howeffectiveismagneticinsulation§ Whataretheend-losses

Detailed accounting of the energy in the system at each phase is critical to distinguish

between hypotheses

Laser Heating

Recently,progresshasbeenmadeinresolvingthelaserenergydepositionproblem

§ Acombinedapproachoflasertransmissionstudiesandgas-cell studiesisbeingusednow

§ Wehavealreadymadetremendousprogressinunderstandingtransmittedandscatteredenergy

§ Moreworkneededonunderstandingenergydeposited

6

Gas cell experiments

ZBL

LEH foil (1.5 µm polyimide)

53 psi He gas fillProbe laser

Heated plasma

Backward scatter Laser shadowgram

Heated plasmaLEH foil

Gas cell

LEH transmission studies

Forward scatterBackward scatter

Transmitted energy measurement

LEH foil

1.5 µm polyimide

ZBL

Material courtesy Matthias Geissel and Adam Harvey-Thompson

Wewilldevelopthecapabilitytomeasurethegastemperatureasafunctionoftime

§ Neonisbelieved tobesensitivetosufficiently lowtemperatures totracktheincreaseinTe andsubsequentdecayastheenergy redistributesandradiatesaway

§ Thespectrometerwillviewtheheatedgasthrough theLEH

§ Theproposed instrument iscompatiblewithdownlineaswellasZBLonlyshotsonZandinPECOS

7

ZBL

LEH foil (1.5 µm polyimide)

Heated plasma

Backward scatter

Gas cell

Time resolved Ne spectroscopy

D2+Ne

Material courtesy Matthias Geissel and Adam Harvey-Thompson

Wearealsodevelopingnewtargetdesignstoenableside-onimagingandspectroscopyofNeemission

8

LEH appears in FOVWindows for x-ray transmission

End-plug overlap (required for pressure)

Gas fill

Mounting holes to anode

LEH washer

Anode

Different window designs for different applicationsCompatible with a variety of in-chamber imaging and spectroscopy diagnostics

Material courtesy Adam Harvey-Thompson and Matt Gomez

Weareexploringvariouspump/probeexperimentstotracktheevolutionofmixgeneratedduringpreheat

§ Theideaofexternallyprobingthepreheatedplasmaisbeingexplored§ Inprinciple,thiscanbedonewithaseparatelaserorx-raysource§ Lettheplasmaevolve,thenexcitethecontaminantstoproduceKα emission§ Byspatiallyresolvingtheemission,wecantrackwherethemixgoesasafunctionoftime§ Doesnotrelyonmaterialbeinghotinordertodetectit

9

Heated plasma

D2

t0 +�tX-ray source

Gas cell

D2 D2

Heating beam

Optical Probe beam

t0 t0 +�t

or

Characteristic x-rays from contaminants

Characteristic x-rays from contaminants

Space resolving x-ray spectrometer

AdditionalongoingeffortonmitigationstrategiesCryogenicGasfillplatform

10

~100 nm window è allows cushionless“thick-end” liner

Initial radiography campaign showed agreement with early time behavior, but some problems with shots

Twohighriskwindowlessdesignsarebeingexploredatalowlevel

Cryo-pool

11

D2 Liq/Ice

Nowindow

Form a pool of liquid, or disk of iceUse the preheat laser to create a plume that dynamically generates your hot spot fuelFoam shot on EP to scope this

Use a thick membraneMechanically burst the membrane ~1µs before preheatHeating beam propagates through the gas rarefaction, into the imploding region

Thick Membrane

Thebroadthemeforaddressingexistinghypothesesisenergybalance

§ Howmuchenergyisabsorbed§ Howmuchenergyisscattered§ Howmuchmixisgenerated,

wheredoesitgo

12

Radial Posi tion [mm]

AxialPosition[m

m]

z2839: Ar Imager

−2 −1 0 1 2−10

−9

−8

−7

−6

−5

−4

−3

−2

−1

0

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

§ Whatisthehot-spotpressure,mass,volume

§ Whatisthedrivepressurenearstagnation

§ Howwellisthelinerconfiningthefuel

§ Whatistheradiationlossinflight§ Howeffectiveismagneticinsulation§ Whataretheend-losses

Detailed accounting of the energy in the system at each phase is critical to distinguish

between hypotheses

Implosion/Compression

InCY17wewillextendpreviousworkonthestagnationdynamicstomagnetizedliners

§ Wehavedemonstratedtheabilitytoradiographicallymapoutstagnationinmoderateconvergence(CR~8)implosionswithunmagnetized liners

§ Wewillapplythismethodologyto liquidD2-filledMagLIF linersw/appliedBz§ ”standard”AR=6liner§ Mass-matchedlinerwithETImitigation

13

Powerfeedmodificationsarebeingpursuedtoimprovedriverenergycoupling

§ Thepowerfeedinductancehasadramaticinfluenceoncouplingdriverenergytothe load

§ Higherinductancefeedsdroptheavailablecurrentandincreasethevoltageattheconvolute,exacerbatinglosses

§ Lowerinductancefeedlikelyneedstobeaccompaniedbytargetmodificationstofullyrealizethebenefits

§ Increasingcurrentisimportanttotestscaling 14

Lincoln feed – 4 mm minimum gap Conical feed – 3 mm minimum gapReturn can

Field Coil

convolute post

Standard Feed Low Inductance Alternatives**Target

Calculated* Load Currents

*Circuit model developed by Brian Hutsel, **power feeds designed by Matt Gomez

Wewillbetestingtheeffectivenessofmodifyingthetargetdiameteratincreasingcurrentdelivery

§ IncreasingtargetODatfixedARhasaparadoxicaleffect§ Initiallyslowstheimplosion

(bad)§ Thisreducesthedynamic

(dL/dt)voltage(good)§ Thisinturn increasesthedrive

current,allowingthepeakvelocitytobelargelyrecovered

§ Alsomoves innersurfaceawayfromlaserinteractionregion

§ Neteffectisthatthedriverisabletomoreeffectivelycoupletotheload(bettermatchedimpedance)

15

Circuit model predictions* for new Low-L design with various diameter targets

“inductive dip” caused by large dL/dt near stagnation

*Circuit model developed by Brian Hutsel

Wearealsoexploringseveralwaystoaccuratelycharacterizecurrentdelivery

§ Wehavedevelopedthecylindrical analogtotheNIF“key-hole”experiments tocompliment electricaldiagnostics

§ Multi-point radialPDV(MPDV*)allowsustomeasurethelinervelocityatupto6azimuths

§ Currently goesto~40km/s, butextension to>100km/sinprogress

§ Thevelocity historyisadirectprobeofthedrivepressure history

§ CanbeconvertedtodrivecurrentthroughMHDsimulation

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Probes

Example Velocity Spectrumfibers

liner

*MPDV developed by Dan Dolan in conjunction w/ Ray Lemke, Matt Martin and Patrick Knapp

Example Velocity Compared to Simulation

InadditiontoincreasingPdV work,weaimtomeasureandmitigatelosses

§ Early-timemixfromlaser-windowandlaser-wall interactionscanbedevastating:webelieve that~0.1%endcapmixandfew-%windowmixare introducedduringpreheat

§ Mixnearstagnation(~1%wallmix)ismuchlessharmful§ Spectroscopic tracershavebeenusedtotrackendcapmaterial§ Time-resolvedheating,windowmix,andradlossdiagnosticsare

possiblewith100ppmAr andchlorinatedplastic;time-resolvedspectrometers required forfieldingonintegratedshots

Co tracer

Cl tracer

Ardopant

*Calculations courtesy Steve Slutz

Thebroadthemeforaddressingexistinghypothesesisenergybalance

§ Howmuchenergyisabsorbed§ Howmuchenergyisscattered§ Howmuchmixisgenerated,

wheredoesitgo

18

Radial Posi tion [mm]

AxialPosition[m

m]

z2839: Ar Imager

−2 −1 0 1 2−10

−9

−8

−7

−6

−5

−4

−3

−2

−1

0

0

1000

2000

3000

4000

5000

6000

7000

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9000

10000

§ Whatisthehot-spotpressure,mass,volume

§ Whatisthedrivepressurenearstagnation

§ Howwellisthelinerconfiningthefuel

§ Whatistheradiationlossinflight§ Howeffectiveismagneticinsulation§ Whataretheend-losses

Detailed accounting of the energy in the system at each phase is critical to distinguish

between hypotheses

Stagnation

PHS =

vuuute

⌫⇢l`(h⌫)1/3Y⌫

8⇡2m

2p�hR

2⌧(1 +

Pi xiZi)

R 1

0r̃dr̃

e�h⌫/Te

T 2e

✓1 +

Pi xi

jijD

◆

Wearedevelopingthemeanstomeasurethefuelpressureusingindependentmethods

19

X-rays

PHS = (Z + 1)

s2YDD

⌧2VR 1

0r̃dr̃h�viDD/T 2

i

Neutrons

Necessary MeasurementsNeutron Yield

Total X-ray yieldFuel volume

Ion temperatureElectron temperatureLiner areal densityEmission duration

Mix (Z)Must improve uncertainties to discern trends

ThereisasignificantongoingefforttomodeltheZenvironmentinordertoimprovetheprecisionofouryieldandTi measurements

§ MCNPmodeling ofvariousnTOF LOS’s§ Exploringexperimental campaignsto

calibratethemodels§ AbsolutecalibrationofnTOF

detectors

20

Modeled scatter*

*Model for LOS50 developed by Edward Norris and Kelly Hahn

Same LOS, different detectors see different signal

These discrepancies contribute significantly to uncertainty in Ti

FilteredpinholeimagescanbeusedtoreconstructfuelTe,linerarealdensityandtotalx-rayyield

§ Existinginstrumenthaspoorspatialresolution (~100µm)§ Imagesareintegrated radially,butresolvedaxially§ Withabsolutex-rayyield,mix,andemissionradius, canalsoget§ Workingonformalizing parameterestimationanddefining uncertainties 21

hP i, �P (z)

hP i

Te [keV]⇢`R [g/cm2]

Images provided by Matt Gomez

- Measured intensity

- Simulated intensity

- Filter transmission & detector response

Xj

Fj

⇣j

�2r =

1

N �m

X

j

✓Xj � ⇣j

�j

◆2

⇣j = 8⇡2m

2pP

2HS(1 +

X

i

xiZi)⌧�hR2

Z 1

0

d⌫Fje�⌫⇢l`

Z 1

0

r̃dr̃

✓1 +

X

i

xiji

jD

◆e

�h⌫/Te

T

2e h⌫

1/3

1 2 3 4

1011

1012

1013

DD

NeutronYield

I on Temperature [keV]

Be (Ta l l , t hi n)

A l (Ta l l , t hi n)

B e ( Sho r t , t hi ck )

A l ( Sho r t , t hi ck )

∝ ⟨σv ⟩

Wehaveshownadependenceoftargetperformanceonmix,butsignificantuncertaintiesremain

§ Wehaveclearindicationsofthepresenceofhotcontaminants§ Uncertainhowmuchistrulymixedintheparticipatingfuel§ ObservedhotFeemission* couldbefromhotspot,orcould

belaterintime§ Uncertainhowmuchwindowmaterialismixedin

§ Indications thatthisamountscaleswithlaserenergydeposition

§ Potentialsolutions aredegeneratewithrespecttowindowmixandpreheatenergy

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0 0.5 1 1.5 2 2.5 3 3.5x 1012

Tall

Short

Neutron Yield

Targ

et

AluminumBeryl l ium

0 0.5 1 1.5 2 2.5 3 3.5x 1012

Tall

Short

Neutron Yield

Targ

et

AluminumBeryl l ium

50%

10x

-1 -0.5 0 0.5 1

Horiz. Pos. [mm]

-6

-4

-2

0

2

4

6

Ve

rtic

al P

ositio

n [

mm

]

z2850

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6500 7000 7500 8000

Energy [eV]

-6

-4

-2

0

2

4

6

z2850 XRS3-AR

0

100

200

300

400

500

0

100

200

300

400

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Counts

He-like Fe + sats.Fe Kα1,2

He-like Ni + sats

Fe He-βNi Kα1,2

Fe K-edge

-1 -0.5 0 0.5 1

Horiz. Pos. [mm]

-6

-4

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0

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Ve

rtic

al P

ositio

n [

mm

]

z2850

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6500 7000 7500 8000

Energy [eV]

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z2850 XRS3-AR

0

100

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500

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100

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Counts

Spectra processing and analysis courtesy Eric Harding and Stephanie Hansen

Mix is measured by impurity line emissionand absolute x-ray yields

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§ X-ray yields from filtered silicon diodes indicate ρf ~ 0.3 g/cc (with mix), dependent on Δt and volume

§ XRS3 and CRITR impurity line emission intensities indicate ~few % Be believed to be from late-time instability driven mixing

§ Ratios of neutron to x-ray yields indicate that endcap and possibly window mix increase with preheat energy

Wehavedemonstratedtheabilitytoimpactthestagnationmorphologythroughcontrollingtheimplosion

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w/ dielectric coating

No coating ”spotty” emissionHot Fe emission

Little Hot Fe emissionUniform K-α Fe emission

Helical columnHighly variable intensity

Much straighter columnUniform brightness

Despite ”improved” morphology, neutron yield and ion temperature decreased

X-ray Spectrum

X-ray Spectrum

Implosion only experimentsIntegrated experiments

Radiographs provided by Tom Awe and Dave Ampleford

Wearecurrentlydesigningandbuildinganin-chambertimeresolvedPHCforstudyinghot-spotevolution

2558 59 60 61

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Posi t i on [mm]

Position[m

m]

z 2839 MLM-C Frame 6

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Posi t i on [mm]

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Posi t i on [mm]

Position[m

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z 2839 MLM-C Frame 8

0.05

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0.25

0.3

3.095 3.1 3.105 3.11 3.115

0

5

10

time [µs]

Signal[V

]

XRBT-t5MA≈101 ns

1 mils Kapton10 mils Kapton

Previous measurements hint at important features in hot spot evolution, but instrument did not have sufficient resolution or sensitivity

target

pinholes

W MCP Enclosure

M = 0.5, 1 or 3

�x � 25 µm�t � 250 ps8 frames

Independent vacuum

Instrument design by Christopher Ball and Matt Gomez

TheCY17Zshotallocationreflectsthesepriorities

26*Preconditioning shot allocation does not include PECOS or OMEGA/OMEGA-EP experiments

10 days: split between lowering inductance to increase drive current and better diagnosing current delivery

5 days: MagLIF Cryo8 days: Develop and characterize new baseline2 days: Calibration1 days: Electron temperature measurement

4 days: Stagnation Hydrodynamics8 days: Mix techniques/characterization/mitigation2 days: Liner diameter scan1 days: Tritium development

5 days: Integration of new platforms

Driver/ Target coupling

Target Preconditioning*

Implosion/ Stagnation

Int.

MagLIF Relevant Shot days: 48

Focusing heavily on preconditioning as interpretation of stagnation is predicated on understanding initial conditions