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Home / Publications / Journals / Fusion Science and Technology / Volume 43 / Number 1 / Pages 55-66

Numerical Raytrace Verification of Optical Diagnostics of Ice Surface Roughness for Inertial Confinement Fusion Experiments

Jeffrey A. Koch, Thomas P. Bernat, Gilbert W. Collins, Bruce A. Hammel, Andrew J. MacKinnon, Charles H. Still, James D. Sater, Donald N. Bittner

Fusion Science and Technology / Volume 43 / Number 1 / January 2003 / Pages 55-66

Technical Paper

Targets for future laser-fusion ignition experiments will consist of a frozen deuterium-tritium ice layer adhering to the inner surface of a spherical shell, and the specifications for the inner surface quality of this ice layer are extremely demanding. We have developed a numerical raytrace model in order to validate backlit optical shadowgraphy as an ice-surface diagnostic, and we have used the code to simulate shadowgraph data obtained from mathematical ice layers having known modal imperfections. We find that backlit optical shadowgraphy is a valid diagnostic of the mode spectrum of ice-surface imperfections for mode numbers as high as 80 provided the experimental data are analyzed appropriately. We also describe alternative measurement techniques, which may be more sensitive than conventional backlit shadowgraphy.

 
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