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Streaked radiography of an irradiated foam sample on the National Ignition Facility
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10.1063/1.4793727
/content/aip/journal/pop/20/3/10.1063/1.4793727
http://aip.metastore.ingenta.com/content/aip/journal/pop/20/3/10.1063/1.4793727

Figures

Image of FIG. 1.
FIG. 1.

Diagram and photos of the streaked radiography setup with a streak camera detector. Distances and relative sizes are not to scale. (a) Diagram showing the relative orientation of the slot-apertured backlighter, the hohlraum with foam pattern, and streak camera. (b) Photograph showing a slot-apertured backlighter used in a NIF experiment. This photograph shows the tantalum, gold, and CH layers of the slot substrate, the clear CH standoff, and the nickel microdot x-ray source. (c) Photograph of a NIF hohlraum with foam and hohlraum background mask. The silicon mounting ring is located near the plane where the hohlraum and mask meet. (d) Photograph of a foam with a single 2w pattern. The black box outlines the imaged region of the foam and the silicon ring is visible outside the radius of the bright gold flange.

Image of FIG. 2.
FIG. 2.

A diagram of the full streaked radiography target with beams, shown side-on, perpendicular to the C-clamp. Dante shields are omitted. Included are vertical distances between key points on the target. (1) is the hohlraum background mask face, (2) is the foam plane, (3) is the laser entrance hole, which is also located at target chamber center, (4) is the location of the backlighter imaging aperture, and (5) is the nickel microdot emitter, where the backlighter beams are pointed. Note that the imaging plane of the primary diagnostic, the DISC x-ray streak camera, is positioned 440 mm above location (3).

Image of FIG. 3.
FIG. 3.

N110318-003 drive laser pulse and drive temperature. These data arerepresentative of the drive pulse on all the experiments discussed in this paper. The black dashed and solid lines are the requested and delivered average laser power per beam, respectively. The laser pulse was 8.7 ns in duration and had a peak power of 0.46 TW.

Image of FIG. 4.
FIG. 4.

Diagrams of the four foam patterns used in this campaign, shown from the top and side views. All foams are 200 μm thick and 6.2 mm wide. (a) Single, 1w foam pattern. The annular pattern width is 200 μm, the same as the foam thickness. (b) 1w slanted foam pattern, where a 200 μm wide annulus is machined at 45° to the foam normal. The slant is oriented such that the pattern on the side of the foam closest to the LEH is closer to the center of the hohlraum. (c) Double 1w foam pattern. Each annulus is 200 μm wide and are separated by 150 μm of foam. (d) Single, 2w foam pattern. The annular pattern width is 400 μm, twice the foam thickness.

Image of FIG. 5.
FIG. 5.

Layout of NIF diagnostics for the streaked radiography experiments, as seen from NIF 0-0. Target was held and positioned using TARPOS, and located and aligned to beams using TAS, which was held and moved by TASPOS. Not shown is the DISC diagnostic, located in DIM 0-0.

Image of FIG. 6.
FIG. 6.

Sample simulation lineouts for the single, 1w pattern. Shown are lineouts at t = 0.25 ns (dashed line) and t = 4 ns (solid line), with prominent features labeled. Pattern walls are shown for both lineout times. At t = 4 ns, shocks in the foam and the ablated material that has collected at the pattern center are also labeled.

Image of FIG. 7.
FIG. 7.

(a) Streaked radiography image of the evolution of a foam with a single 1w (200 μm) pattern. (b) Lineouts in space are shown at t = 0.25, 2, 4, and 6 ns, showing the evolution of the material. The transmission is scaled by setting the x-ray transmission through the undisturbed foam at t = 0.25 ns to 0.25, as predicted by simulations.

Image of FIG. 8.
FIG. 8.

Spatial profiles of the 1w pattern streaked data at four different times, as compared to simulations. Data are black, solid curves, and simulations are red, dashed curves. Lineouts are averaged over 750 ps. (a) Lineouts at t = 0.25 ns. (b) Lineouts at t = 2 ns. (c) Lineouts at t = 4 ns. (d) Lineouts at t = 6 ns.

Image of FIG. 9.
FIG. 9.

(a) Streaked radiography image of the evolultion of a foam with a slanted 1w pattern. Notice the asymmetry in the evolution as the inside corner of the pattern is ablated. A shock is visible in the foam on both sides of the pattern. After 6 ns, the hohlraum background signal is comparable to the backlighter signal. (b) Lineouts in space are shown at t = 0, 2, 4, and 6 ns, showing the evolution of the material. The transmission is scaled by setting the x-ray transmission through the undisturbed foam at t = 0.25 ns to 0.25, as predicted by simulations.

Image of FIG. 10.
FIG. 10.

Spatial profiles of the slanted 1w pattern streaked data at four different times, as compared to simulations. Data are black, solid curves, and simulations are red, dashed curves. Lineouts are averaged over 750 ps. (a) Lineouts at t = 0.25 ns. (b) Lineouts at t = 2 ns. (c) Lineouts at t = 4 ns. (d) Lineouts at t = 6 ns.

Image of FIG. 11.
FIG. 11.

Pseudocolor plots of a KULL simulation of the slant 1w feature. The upper half of each image represents radiation temperature, while the lower half shows log density as the ablative heat wave moves through the foam. Note that the maximum radiation temperature in each plot is different, while the minimum temperature is fixed. (a) t = 2 ns. Note the hot spot near the wall and the material beginning to collect at the center of the foam pattern. (b) t = 5.7 ns. Material has begun to fill the hohlraum, and the pattern has evolved to be wider and partially filled with ablated material.

Image of FIG. 12.
FIG. 12.

(a) Streaked radiography image of the evolution of a foam with a double 1w pattern. (b) Lineouts in space are shown at t = 0.25, 2, 4, and 6 ns, showing the evolution of the material. The transmission is scaled by setting the x-ray transmission through the undisturbed foam at t = 0.25 ns to 0.25, as predicted by simulations.

Image of FIG. 13.
FIG. 13.

Spatial profiles of the double 1w pattern streaked data at four different times, as compared to simulations. Data are black, solid curves, and simulations are red, dashed curves. Lineouts are averaged over 750 ps. (a) Lineouts at t = 0.25 ns. (b) Lineouts at t = 2 ns. (c) Lineouts at t = 4 ns. (d) Lineouts at t = 6 ns.

Image of FIG. 14.
FIG. 14.

(a) Streaked radiography image of the evolution of a foam with a single 2w pattern, where the pattern width is twice the thickness of the foam (400 μm). b) Lineouts in space are shown at t = 0.25, 2, 4, and 6 ns, showing the evolution of the material. The transmission is scaled by setting the x-ray transmission through the undisturbed foam at t = 0.25 ns to 0.25, as predicted by simulations.

Image of FIG. 15.
FIG. 15.

Spatial profiles of the single 2w pattern streaked data at four different times, as compared to simulations. Data are black, solid curves, and simulations are red, dashed curves. Lineouts are averaged over 750 ps. (a) Lineouts at t = 0.25 ns. (b) Lineouts at t = 2 ns. (c) Lineouts at t = 4 ns. (d) Lineouts at t = 6 ns.

Tables

Generic image for table
Table I.

Shot statistics for data shots discussed in this paper. Note that the backlighter flatfield shot (N110319-002) imaged the illumination from a backlighter only, and no hohlraum was used on that shot. For all shots, drive energy, peak drive radiation temperature (Tr ), and backlighter energy were all within requirements for total variation from nominal values.

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/content/aip/journal/pop/20/3/10.1063/1.4793727
2013-03-05
2014-04-21
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Streaked radiography of an irradiated foam sample on the National Ignition Facility
http://aip.metastore.ingenta.com/content/aip/journal/pop/20/3/10.1063/1.4793727
10.1063/1.4793727
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