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Thin Oxides as a Copper Diffusion Barrier for NIF Beryllium Ablator Capsules

K. P. Youngblood, H. Huang, H. W. Xu, J. Hayes, K. A. Moreno, J. J. Wu, A. Nikroo, C. A. Alford, A. V. Hamza, S. O. Kucheyev, Y. M. Wang, K. J. Wu

Fusion Science and Technology / Volume 63 / Number 2 / March-April 2013 / Pages 208-212

Technical Paper / Selected papers from 20th Target Fabrication Meeting, May 20-24, 2012, Santa Fe, NM, Guest Editor: Robert C. Cook /

The NIF point design uses a five-layer capsule to modify the X-ray absorption in order to achieve optimized shock timing. A stepped copper dopant design defines the layer structure. The production of the capsule involves pyrolysis to remove the inner plastic mandrel. Copper atoms diffuse radially and azimuthally throughout the capsule during pyrolysis. This diffusion significantly diminishes the capsule performance during implosion. Thermal and coated oxide barrier layers employed between layers mitigate the diffusion of copper during the mandrel removal process. The copper atoms do not diffuse through this barrier during pyrolysis. A capsule fabrication method that produces a capsule with a thin oxide layer will be discussed.

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