Status of the National Ignition Facility project

The ultimate goal of worldwide research in inertial confinement fusion (ICF) is to develop fusion as an inexhaustible, economic, environmentally safe source of electric power. Following nearly thirty years of laboratory and underground fusion experiments, the next step toward this goal is to demonstrate ignition and propagating burn of fusion fuel in the laboratory. The National Ignition Facility(NIF) Project is being constructed at Lawrence Livermore National Laboratory (LLNL), for just this purpose. NIF will use advanced Nd-glass laser technology to deliver 1.8 MJ of 0.35-um laser light in a shaped pulse, several nanoseconds in duration, achieving a peak power of 500 TW. A national community of U.S. laboratories is participating in this project, now in its final design phase. Franceand the United Kingdom are collaborating on development of required technology under bilateral agreements with the US. This paper presents thestatus of the laser design and development of its principal components and optical elements

Saturation in heteronuclear photoassociation of 6Li7Li

We report heteronuclear photoassociation spectroscopy in a mixture of magneto-optically trapped 6Li and 7Li. Hyperfine resolved spectra of the vibrational level v=83 of the singlet state have been taken up to intensities of 1000 W/cm^2. Saturation of the photoassociation rate has been observed for two hyperfine transitions, which can be shown to be due to saturation of the rate coefficient near the unitarity limit. Saturation intensities on the order of 40 W/cm^2 can be determined.Comment: 5 pages, 3 figures, to appear in Phys. Rev. A (Rapid Communication

On the Anisotropy of the Ductile to Brittle Transition Behavior in a Wrought and in Two Oxide Dispersion Strengthened FeCrAl Steels

The directionality of the ductile-brittle transition behavior of two oxide-dispersion-strengthened (ODS) FeCrAl steels with similar chemical compositions, tensile properties, and sub-micrometric grain sizes but different processing routes, and a Zr-particle strengthened FeCrAl steel manufactured by high vacuum melting is discussed. Despite the similarities of the ODS FeCrAl steels, strong differences in the lower and upper shelf energy and the ductile to brittle transition temperature were observed for longitudinal through thickness notched specimens. Although the lower and upper shelf energies of longitudinal surface-notched specimens of ODS FeCrAl steels are similar, a strong difference in the ductile-to-brittle transition temperature is observed. For through-thickness notched and surface-notched specimens taken transversely, the analyzed ODS FeCrAl steels show a similar ductile-to-brittle behavior. In general, the FeCrAl alloy strengthened with Zr-particles presents a more isotropic behavior and a higher ductile-to-brittle transition temperature than the ODS FeCrAl steels. In addition, the upper shelf energy of the FeCrAl steel strengthened with Zr-particles is significantly higher than that of the ODS FeCrAl steels.The authors acknowledge financial support to Spanish Ministerio de Economia y Competitividad (MINECO) in the form of a Coordinate Project (MAT2016-80875-C3-1-R). The authors are grateful for the dilatometer tests by Phase Transformation laboratory. This work contributes to the Joint Programme on Nuclear Materials (JPNM) of the European Energy Research Alliance (EERA).Peer Reviewe