Inhomogeneous Copper Diffusion in NIF Beryllium Ablator Capsules

• DOI: 10.13182/fst13-tfm20-24
• Publication Date: 2015-05-28T17:38:46Z
• Authors: H. Huang; H. W. Xu; K. P. Youngblood; D. R. Wall; R. B. Stephens; K. A. Moreno; A. Nikroo; K. J. Wu; M. Wang; A. V. Hamza
• Keywords: National Ignition Facility

The National Ignition Facility point design uses a five-layer capsule to modify the X-ray absorption in order achieve optimized shock timing. A stepwise copper dopant defines layer structure; however, as-deposited Cu distribution is significantly altered during CH mandrel removal by pyrolysis. changes are significant: (a) diffuses on average several microns, distance more than an of magnitude larger predicted from bulk diffusion data, and (b) distribution, as result diffusion, highly heterogeneous, introducing local variation [approximately]0.06 at. % near original interface. In this study, we developed quantitative techniques measure explored its correlation beryllium microstructures. Plausible mechanisms mitigation methods will be discussed. These findings enable accurate evaluation expected target performance.