Long duration backlighter experiments at Omega.
We have successfully demonstrated a 7.5 ns duration pinhole-apertured backlighter at the Omega laser facility. Pinhole-apertured point-projection backlighting for 8 ns will be useful for imaging evolving features in experiments at the National Ignition Facility. The backlighter consisted of a 20 microm diameter pinhole in a 75 microm thick Ta substrate separated from a Zn emitter (9 keV) by a 400 microm thick high-density carbon piece. The carbon prevented the shock from the laser-driven surface from reaching the substrate before 8 ns and helped minimize x-ray ablation of the pinhole substrate. Grid wires in x-ray framing camera images of a gold grid have a source-limited resolution significantly smaller than the pinhole diameter due to the high aspect ratio of the pinhole, but do not become much smaller at late times.
Reighard
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Lawrence Livermore National Laboratory, Livermore, California 94551, USA. reighard2@llnl.gov
Glendinning
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Young
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Hsing
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Foord
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Schneider
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Lu
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Dittrich
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Wallace
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Sorce
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