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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