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NIF Target Assembly Metrology Methodology and Results

E. T. Alger, J. Kroll, E. G. Dzenitis, R. Montesanti, J. Hughes, M. Swisher, J. Taylor, K. Segraves, D. M. Lord, J. Reynolds, C. Castro, G. Edwards

Fusion Science and Technology

Volume 59 / Number 1 / January 2011 / Pages 78-86


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Inertial confinement fusion (ICF) experiments at the National Ignition Facility (NIF) require cryogenic targets at the 1-cm scale to be fabricated, assembled, and metrologized to micron-level tolerances. During assembly of these ICF targets, there are physical dimension metrology steps to be made of the components, subassemblies, and completed targets. Metrology is primarily completed using optical coordinate measurement machines that provide repeatable measurements with micron precision, while also allowing in-process data collection for absolute accuracy in assembly. To date, 51 targets have been assembled and metrologized, and 34 targets have been successfully fielded on NIF relying on these metrology data. In the near future, ignition experiments on NIF will require tighter tolerances and more demanding target assembly and metrology capability.

Metrology methods, calculations, and uncertainty estimates will be discussed. Target diagnostic port alignment, target position, and capsule location results will be reviewed for the 2009 Energetics Campaign. The information is presented via control charts showing the effect of process improvements that were made during target production. Certain parameters, including capsule position, met the 2009 campaign specifications but will have much tighter requirements in the future. To meet these new requirements assembly process changes and metrology capability upgrades will be necessary.

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