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X-ray driven implosions at ignition relevant velocities on the National Ignition Facilitya)
a)Paper NI2 4, Bull. Am. Phys. Soc. , 201 (2012).
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10.1063/1.4803915
/content/aip/journal/pop/20/5/10.1063/1.4803915
http://aip.metastore.ingenta.com/content/aip/journal/pop/20/5/10.1063/1.4803915
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

Capsule pie diagrams for the nominal “Rev 5” ignition capsule (left) and symmetry capsule (right) with silicon dopant layers. Dimensions are in microns. Both capsules use the same podium profile for the Si dopant, with clean CH (plastic) on the inner-most and outer-most layers. The central layers have nominally 1%, 2%, and 1% silicon (by atom) doped in the plastic.

Image of FIG. 2.
FIG. 2.

Velocity vs. ablator center-of-mass radius for two 1D calculations using the same x-ray drive source. The black curve shows the center-of-mass velocity for a symmetry capsule—this quantity is measured in backlit convergent ablator experiments. The red curve shows the mass-average fuel velocity for the equivalent DT-layered ignition capsule. The fuel velocity is higher than the ablator velocity due to convergence effects at small radius. The maximum of is typically 10%–15% higher than that of .

Image of FIG. 3.
FIG. 3.

Rocket curves for a thicker (215 m) DT capsule and (229 m) symcap from two 1D calculations that use the same x-ray drive source. The blue dashed curve is simply Eq. (5) , , and passes through the symcap simulation. The ignition mass/velocity goal ,  = 0.25 mg is shown as a red ×. The error bar represents the total uncertainty in inferring the mass from a convergent ablator experiment. This error bar is not meant to represent a tolerance on the ignition mass goal.

Image of FIG. 4.
FIG. 4.

Rocket curves for nominal ( ) symcaps from twelve convergent ablator experiments and their corresponding 2D post-shot calculations. The twelve shots vary in laser peak power, capsule dopant concentration, LEH size, and hohlraum wall material. The data generally lie on the simulated rocket curves within the measurement uncertainty. The thickness of the bundle of simulated rocket curves is in mass or in velocity.

Image of FIG. 5.
FIG. 5.

Rocket curves for nominal ( ) symcaps from twelve convergent ablator experiments and their corresponding 2D post-shot calculations, focused near the end of the acceleration phase. The symcap mass/velocity goal, ,  = 0.46 mg, is shown by the black ×. A simulation of the nominal Si capsule that reaches the symcap velocity goal is shown by the red dashed line. This rocket curve reaches with mass below the goal of  = 0.46 mg.

Image of FIG. 6.
FIG. 6.

Rocket curves for nominal ( ) and thick ( ) symcaps from twelve convergent ablator experiments designed to reach and their corresponding 2D post-shot calculations. The red curves and black data points are a subset of the twelve experiments shown in Fig. 5 . The red dashed line is as in 5. The blue data points and solid curve are results for a backlit experiment with a 20 m thicker ( ) capsule. The blue dashed curve is a simulation of this thicker capsule driven to the symcap velocity goal, .

Image of FIG. 7.
FIG. 7.

Radiation brightness temperature inferred from the DANTE and SXI diagnostics (cf. Eq. (7) ) for the 520 TW symcap shot N120705. The for one of the frequency-dependent-sources (FDS) used in the 1D flux-scaling is shown in red for comparison. The launch time, rate-of-rise, and general shape of the FDS are taken from the experimental data. The 1D simulation using this particular source reproduces the measured x-ray bang-time of N120705. The maximum of this source is slightly lower than the data using an error bar to represent thecombined uncertainty of DANTE, SXI, and the analysis method approximations.

Image of FIG. 8.
FIG. 8.

Velocity vs. x-ray bang-time for symmetry capsule shot N120705 and convergent ablator shot N121007, compared with a 1D flux-scaling. The convergent ablator data for center-of-mass velocity and x-ray bang-time “pin” the scaling, allowing a velocity estimate for the higher-power N120705 shot based only on its bang-time.

Image of FIG. 9.
FIG. 9.

Laser power delivered to the hohlraum for the symcap shot N120705 and the corresponding convergent ablator shot N121007. The average peak-power was 520 TW for N120705 and 470 TW for N121007. The requested power for N121007 was reduced from 514 TW to 500 TW. The power was further reduced due to diverting two quads to the backlighter foil and losing a third quad to mechanical failure. These laser pulses correspond to the × symbols in Fig. 8 .

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2013-05-09
2014-04-19
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: X-ray driven implosions at ignition relevant velocities on the National Ignition Facilitya)
http://aip.metastore.ingenta.com/content/aip/journal/pop/20/5/10.1063/1.4803915
10.1063/1.4803915
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