T. C. SangsterUniversity of RochesterLaboratory for Laser Energetics

56th Annual Meeting of theAmerican Physical SocietyDivision of Plasma Physics

New Orleans, LA27–31 October 2014

Improvements in Cryogenic DT Target Performance

New capabilities are under development to support high-performance cryogenic implosions* on OMEGA in early 2015

Summary

E23688 *V. N. Goncharov et al., JO4.00006, this conference.

• TheimplementationofdynamicbandwidthreductiononOMEGAwill provide an additional few kilojoules for implosion experiments

• Anewsetofsymmetric-drivephaseplates(SG5) will significantly improve the drive uniformity

• Newdiagnosticsarebeingdevelopedtoreduceuncertainty in the inferred Px of layered direct-drive implosions

• ImpuritiesintheDTfuelsupply(1H) have been removed using the new Isotope Separation System (ISS)

• ThefirstimplosionswithaT:Disotopicratioof60:40show the expected increase in primary neutron yield

Collaborators

V. N. Goncharov,1 R. Epstein,2 P. B. Radha, R. Betti, T. R. Boehly,R. Earley, C. J. Forrest, D. H. Froula,3 V. Yu. Glebov, E. Hill, S. X. Hu, I. V. Igumenshchev, R. Janezic, J. H. Kelly, T. J. Kessler, T. Z. Kosc,

J. Kwiatkowski, J. A. Marozas, F. J. Marshall,4 R. L. McCrory, P. W. McKenty, D. D. Meyerhofer, D. T. Michel, J. F. Myatt, J. Puth,

N. Redden, J. Reid, S. P. Regan, W. Seka, W. T. Shmayda, A. Shvydky, C. Stoeckl,5 and M. D. Wittman

University of RochesterLaboratory for Laser Energetics

J. A. Frenje, M. Gatu Johnson, and R. D. Petrasso

Massachusetts Institute of Technology

Otherrelevantpresentationsatthismeeting:1. V. N. Goncharov et al., JO4.00006, this conference.2. R. Epstein et al., JO4.00007, this conference.3. D. H. Froula et al., NO4.00013, this conference.4. F. J. Marshall et al., TO4.00001, this conference.5. C. Stoeckl et al., UO4.00011, this conference.

The requirements to increase the stagnation pressure by July 2015 will be mostly implemented by Q2FY15

E23689

• Reducelaserimprintusingdopedablatorsandhigh-Z layers*

• Improvedriveuniformitywithbetterpower-balancealgorithms

• Additionalenergyontargetusingdynamicbandwidthreduction

• Reducecross-beamenergytransfer(CBET) and improve drive uniformity with a new set of phase plates (SG5)

• Installnewinstrumentationtoimprovethemeasurementaccuracy of the central pressure and Px

• Eliminatetargetparticulatesourcestoreduceablation-surfaceRayleigh–Taylor (RT) seeds

• PurifytheDTfuelsupplyandadjusttheT:Dratioformaximumyield(50:50inthegasphase)

*A. J. Schmitt et al., JO400010, this conference;M. Karasik et al., JO400012, this conference.

Dynamic bandwidth reduction is part of the effort to mitigate CBET

E23690

• Front-endmodificationscurrentlyunderwaywillprovideco-propagation of two separate pulse shapes in all 60 OMEGA beams*

• Two-dimensionalsmoothingbyspectraldispersion(SSD) can be applied to either one of the two pulse shapes

• Dynamicbandwidthreductiononastandardcryogenictargetdrivepulse(bandwidth only on the pickets) provides increased energy in the drive

• Followingthemodifications,itwillbepossibletopropagatedifferentspatialprofiles for each pulse (an option for focal-spot zooming* expected in FY16)

D. H. Froula et al., NO4.00013, this conference.

00.0

0.1

0.2

0.3

0.4

1000

Time (ps)

Po

wer

(T

W)

2000

Nobandwidth

SSDbandwidth

A new set of phase plates will improve on-target drive uniformity and reduce light that can seed CBET

E23691

–500

–400

400

800

0

–8000

860 nm, 95% 820 nm, 95%860 nm, 95%

x far field (nm)

y fa

r fie

ld (n

m)

Log scale of far field fromcurrent SG4 equivalent-target-

plane image (ETP)

Log scale of far field fromnew SG5 equivalent-target-

plane image (ETP) log10 (I)

500 –500 0

820 nm, 95%

x far field (nm)500

–4

–3

–2

–1

0

• ThepressureofalayeredDTimplosioncan beinferredtwoways:

1. The central pressure P(0)atbangtimeisgivenby:*

2. The burn average GPH atbangtimeisgivenby:**

A new neutron temporal diagnostic (CryoNTD) will provide an accurate (estimated 10%) measurement of the burn width

E23692

*R. Nora et al., Phys. Plasmas 21, 056316 (2014).**C. Cerjan, P. T. Springer, and S. M. Sepke, Phys. Plasmas 20, 056319 (2013).

Highest OMEGA P(0) = 43 Gbar for shot 69514

The highest OMEGA burn average pressure for shot 69514 is GPH = 31.5 Gbar

. .Yield GbarP RM T

0 27 0 24 10 4 7/

.. .

g cmn DT

mg

nkeV

0 61 16 0 34 0 8–2

# #. x t^ f ^h p h= G

YieldPT V

16hs

#/

p x^ h dT V VT

V1hs

hs 2/pvo^ h #

The CryoNTD is located in P11with optical transport to a streakcamera in the OMEGA EP plenum

(S/B ~ 200)

The estimated impulse responseis ~50 ps, adequate for

50-to 60-Gbar pressures and widthsof 70 to 90 ps

A framed 16-image KB will provide time-resolved x-ray images of the core through stagnation (Q1FY15)

E22996

Gate width: ~ 30 psImage-to-image: ~ 60 ps Spatial resolution: ~ 5 nmEnergy range: 1.5 to 8 keV

Framingcamera

OMEGA Kirkpatrick–Baez (KB)microscope chassis

00

4

8

50 100Position (nm)

AD

U/1

00

150 200

ImageFit

Image Super-Gaussian Fit Difference

Fit ParametersRo (microns):maximum (kADU):exponent:

22.8+/- 0.1 9.63+/- 0.23 2.47+/- 0.14

a/b:phi (deg):background (kADU):

200 by 200 micron region

1.124+/- 0.004 48.1+/- 0.1 -0.58+/- 0.09

Omega Shot 68790: GMXI c

Lineout indicated by dotted line

Output of aq_gaussfit.pro

03/20/2013

Filter: 6 mils Be 2 mils Al

Image (black) and Fit (red)

0 50 100 150Position (microns)

02

4

6

810

AD

U/1

000

3.4 mm

Image center

9.0 mm5.6 mmrinnerrinner

routerrouter

Unshiftedimage circle

rmiddle

1 cm

16 imaging pairsper assembly

Optic assemblyS68790

The gated monochromatic x-ray imager (GMXI) provides a time-integrated KB image today

ThenewISS*purified23.6standardlitersofmixedD:T:Hto extract 3 standard liters of T2 with a purity of 99.7%

E23693

• 12mCireleasedoutof8500Ci processed in September 2014

• Before:T:D:Hwas34%:60%:5% (estimated)

• After:T:D:His60:40:<0.1% (estimated)

*Developed jointly with Savannah River National Laboratory

The60:40T:Dratiowaschosentoprovidea50:50mixturein the gas phase (fractionation) of a layered capsule.

The first experiments with the new DT fuel produced the expected increase in primary yield

E23694

A comparison with our best-performing triple-picket design (a ~ 4) will be done in November 2014.

60:35:5 D:T:Hshot 70805Similar pulse used on shot 70805

0.00

5

10

15

20

0.5 1.0

Time (ns)Measurements:

Yn ~ 4.7 × 1013 (25% 1-D) Ti ~ 3.3 keV

tRnTOF ~ 140 mg/cm2 (60% 1-D)

1-D simulations: a ~ 3.1

IFAR ~ 26 V ~ 380 km/s

Measurements: Yn ~ 2.9 × 1013 (32% 1-D)

Ti ~ 3.8 keV tR ~ 157 mg/cm2 (90% 1-D)

1-D simulations: a ~ 5.3

IFAR ~ 22 V ~ 390 km/s

Las

er p

ow

er (

TW)

1.5 2.0

370 nm

50 nm8 nm

40:60 D:Tshot 75009

7500775009

DT gas

DT ice

CD

DT gas

DT ice

CD

370 nm

55 nm7 nm

The measured DT-to-DD yield ratio shows that the fuel isclosetotheexpected60:40isotopicratio(T:D)

E23695

50(D):50(T)52(D):48(T)55(D):45(T)58(D):42(T)60(D):40(T)64(D):36(T)40(D):60(T)43(D):57(T)45(D):55(T)Yield ratio

1

100

150

200

250

300

350

2 3 4 5

Ion temperature (keV)

DT/D

D (

yiel

d r

atio)

6 7 8

7 October 2014

Summary/Conclusions

E23688 *V. N. Goncharov et al., JO4.00006, this conference.

New capabilities are under development to support high-performance cryogenic implosions* on OMEGA in early 2015

• TheimplementationofdynamicbandwidthreductiononOMEGAwill provide an additional few kilojoules for implosion experiments

• Anewsetofsymmetric-drivephaseplates(SG5) will significantly improve the drive uniformity

• Newdiagnosticsarebeingdevelopedtoreduceuncertainty in the inferred Px of layered direct-drive implosions

• ImpuritiesintheDTfuelsupply(1H) have been removed using the new Isotope Separation System (ISS)

• ThefirstimplosionswithaT:Disotopicratioof60:40show the expected increase in primary neutron yield