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Capsule implosion optimization during the indirect-drive National Ignition Campaign
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10.1063/1.3592170
/content/aip/journal/pop/18/5/10.1063/1.3592170
http://aip.metastore.ingenta.com/content/aip/journal/pop/18/5/10.1063/1.3592170

Figures

Image of FIG. 1.
FIG. 1.

(Color) (a) Schematic of the 300 eV CH indirect-drive ignition target. (b) Capsule cross-section. (c) Total laser power (solid) and radiation temperature Tr at capsule (dashed) versus time.

Image of FIG. 2.
FIG. 2.

(Color) (a) Schematic of the alternate 285 eV Be indirect-drive ignition target. (b) Capsule cross-section. (c) Total laser power (solid) and radiation temperature Tr at capsule (dashed) versus time.

Image of FIG. 3.
FIG. 3.

Predicted probability of ignition versus ignition threshold factor (ITF) is long dashed curve. Predicted ITF distributions before and after capsule tuning experiments and after cryogenically layered capsule experiments are short dashed, solid, and dotted-dashed curves, respectively.

Image of FIG. 4.
FIG. 4.

(Color) Schematic of 14 laser and target parameters varied.

Image of FIG. 5.
FIG. 5.

Ratio of reemitted P2/P0 asymmetry at 400, 700, and 1200 eV photon energies to incident spectrally integrated P2/P0 asymmetry 3 ns into a calculated drive equivalent to a 97 eV Planckian. Solid line is analytic Planckian prediction.

Image of FIG. 6.
FIG. 6.

(Color) (a) Re-emission sphere experimental set-up for NIF shots. (b) Power per beam for 48 inner cone beams (solid), 128 outer cone beams (dashed), and for 16 inner cone beams that would hit patches (dotted-dashed).

Image of FIG. 7.
FIG. 7.

(Color online) Calculated incident P2/P0 integrated over 1st 2 ns for re-emission sphere (black circles) versus ignition capsule (red squares) as a function of inner cone energy fraction.

Image of FIG. 8.
FIG. 8.

(Color) (a) Re-emission sphere experimental set-up with example OMEGA data. (b) Instantaneous P2/P0 x-ray emission data at 900 eV for inner cone fraction = 0.12 from 1.4 mm diameter re-emission sphere using 6.4 mm long hohlraums and 100 eV peak drive. Solid curves are postprocessed results from 3D Hydra simulations assuming full coupling (black) and 90% coupling on the inner cone (purple).

Image of FIG. 9.
FIG. 9.

(Color) (a) P2/P0 of 900 eV (open squares) and 1200 eV (closed circles) x-ray emission from 1.4 mm diameter re-emission sphere versus inner cone fraction at 0.7 ns using 6.4 mm long hohlraums and 100 eV drive. Solid and dashed lines are postprocessed results from 3D Hydra simulations for 1200 and 900 eV channels, respectively. (b) Comparison of measured vs calculated reemission sphere image at 1200 eV for inner cone fraction = 0.12 at t = 1 ns.

Image of FIG. 10.
FIG. 10.

(Color) (a) 1st three shock tuning experimental set-up for NIF shots and simulated VISAR fringe data. (b) Power per beam for 64 inner cone beams (solid), 128 outer cone beams (dashed). (c) Simulated output of leading shock velocity versus time that might be expected with third shock delayed intentionally.

Image of FIG. 11.
FIG. 11.

(Color online) Calculated late time shock trajectories in ablator and fuel in initial Lagrangian coordinates for (a) surrogate capsule filled with liquid D2 and (b) ignition capsule with DT solid and gas.

Image of FIG. 12.
FIG. 12.

Computed (symbols) and analytic (line) (a) change in first shock velocity versus change in power in trough of NIC pulse, (b) change in second shock overtake distance versus change in second shock launch time, (c) change in second shock overtake distance versus change in trough laser power, and (d) change in second shock overtake distance versus change in second shock laser power.

Image of FIG. 13.
FIG. 13.

(Color) OMEGA experimental set-up for testing 1st three shocks reentrant geometry, including example VISAR data.

Image of FIG. 14.
FIG. 14.

Schematic showing important parts of 4th rise, with 2 examples (solid and dashed) yielding same shock coalescence time.

Image of FIG. 15.
FIG. 15.

(Color) Calculated (a) average fuel adiabat deviations and (b) peak shell velocity deviations from nominal vs. up to ±300 ps changes in 4th rise duration and 4th rise mid-point time. The horizontal contours represent ±3.5 eV/ns variability in 4th rise Tr slope and the vertical contours represent ±90 ps in 4th shock breakout time.

Image of FIG. 16.
FIG. 16.

(Color) (a) 4th rise tuning experimental set-up for NIF shots. (b) Power per beam for 64 inner cone beams (solid) and 128 outer cone beams (dashed).

Image of FIG. 17.
FIG. 17.

(Color) (a) OMEGA experimental set-up for testing 4th rise tuning reentrant probing geometry. (b) Example VISAR streak showing signature of shock breakout of interest later in time.

Image of FIG. 18.
FIG. 18.

(Color) Measured Dante Tr during (a) last 5 ns and (b) zooming in on 4th rise of 19 ns long 840 kJ pulses driving 5.44 mm diameter hohlraums at NIF. Different colors represent three separate shots. Dashed lines are linear fits to the data. Shots had nominally identical pulseshapes but smaller wavelength separation (3 vs 8.5 Å) for shot N091030 (red curve) and 50% lower gas-fill for shot N091120 (blue curve).

Image of FIG. 19.
FIG. 19.

Calculated ablator-fuel mix fraction versus ablator mass remaining for Be (squares) and CH (circles) designs, with analytic fits overplotted.

Image of FIG. 20.
FIG. 20.

(Color) Calculated peak implosion velocity and remaining ablator mass sensitivity to variations in peak laser power (along black contours spaced every 7% in thickness) and initial ablator mass (along red contours spaced every 10% in peak flux). The black and red arrows signify increasing flux and thickness, respectively.

Image of FIG. 21.
FIG. 21.

(Color online) (a) Calculated streaked radiograph of BeCu target with 6.7 keV backlighter. (b) Extracted transmission lineout corresponding to r = 300 μm shell radius.

Image of FIG. 22.
FIG. 22.

(Color) (a) Streaked capsule radiography experimental set-up for NIF shots. (b) Power per beam for 64 inner cone beams (solid), 120 outer cone beams (dashed), and 8 50° beams used for backlighter (dotted-dashed).

Image of FIG. 23.
FIG. 23.

(Color) (a) Example of streaked 5.2 keV radiograph of 0.5 mm initial diameter BeCu capsule driven by OMEGA 200 eV, 2.5 ns shaped drive hohlraum. (b) Solid points are extracted peak implosion velocity versus % ablator mass remaining from 6 shots using 30 μm (black) and 40 μm (red) initial thickness graded doped BeCu shells. Open squares are postshot Lasnex simulations.

Image of FIG. 24.
FIG. 24.

Schematics of qualitative variations in P2 and P4 core shapes as a function of changes in cone power balance and in hohlraum length, with pointing staying fixed with respect to LEH plane.

Image of FIG. 25.
FIG. 25.

(Color) Calculated symmetry capsule core P2/P0 (solid) and P4/P0 (dashed) as a function of 4th pulse inner cone fraction for three hohlraum lengths: nominal + 400 μm (red), nominal (black), and nominal − 400 μm (blue).

Image of FIG. 26.
FIG. 26.

(Color) (a) Symmetry capsule core x-ray imaging experimental set-up for NIF shots. (b) Power per beam for 64 inner cone beams (solid) and 128 outer cone beams (dashed).

Image of FIG. 27.
FIG. 27.

(Color) Comparison of calculated trajectory of inner ablator of symmetry capsule (black) versus trajectory of DT fuel of ignition capsule (red). Also shown is total laser power profile.

Image of FIG. 28.
FIG. 28.

(Color online) (a) Calculated (a) P2/P0 and (b) P4/P0 asymmetry for symmetry capsule versus ignition capsule core images for various imposed levels of flux asymmetry.

Image of FIG. 29.
FIG. 29.

(Color) OMEGA 5 keV core images and P2/P0 of emission shape versus inner cone fraction from imploded 50 atm fill CH capsule driven by 1 ns duration 270 eV peak hohlraum drive.

Image of FIG. 30.
FIG. 30.

(Color) (a) Gated 8-10 keV, 10 μm, 70 ps resolution x-ray images from pole and equator view of convergence ratio =15 CH capsules driven by 500 kJ 270 eV peak temperature NIF hohlraums. (b) Extracted P2/P0 (circles) and P4/P0 (diamonds) versus time.

Image of FIG. 31.
FIG. 31.

(Color) Illustrative example of how a number of shots measuring ablator mass remaining will be used to check variability and to set the optimum associated target parameter, the initial ablator thickness, and its 1σ uncertainty.

Image of FIG. 32.
FIG. 32.

Residual variances after tuning due to random measurement, systematic, target metrology, and laser diagnostic errors normalized to budget for each of the laser and target adjustable parameters.

Image of FIG. 33.
FIG. 33.

(Color) Matrix of shot tuning type displayed in chronological order from top to bottom versus laser or target parameter. Green boxes on diagonal mean that shot observable is affected by and sets that parameter, and of-diagonal yellow and orange boxes mean that shot is affected by that parameter but does not set it. Value in each orange box above diagonal is expected cross-coupling sensitivity normalized to error budget.

Tables

Generic image for table
Table I.

Expected initial and residual post-tune 1σ offset from optimum ignition implosion performance, associated initial and post-tune 1σ offsets in optimal laser and target parameters, and required accuracy for tuning associated observables.

Generic image for table
Table II.

Expected sensitivities of capsule implosion observables to 10% increase in key target, laser, and physics parameters.

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2011-06-01
2014-04-20
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Capsule implosion optimization during the indirect-drive National Ignition Campaign
http://aip.metastore.ingenta.com/content/aip/journal/pop/18/5/10.1063/1.3592170
10.1063/1.3592170
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