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Welding Science: A New Look at a Fundamental Technology
has a vital interest in knowing all it can about welding. Dependable welds
are important for maintaining the performance and safety of nuclear weapons.
Welds will also play a key role in the success of the Department of Energys
planned repository for long-term storage of nuclear wastes, which is being
investigated through the Yucca Mountain project. In experiments using
synchrotron radiation and x-ray diffraction, a Livermore team has succeeded
in producing the first-ever maps of real-time microstructural changes
that occur in and around the weld area as a metal melts and resolidifies.
More recently, their experiments have revealed second-by-second changes
in a metals microstructure during welding. Results of recent time-resolved
experiments indicated that nonequilibrium solidification of welds can
occur, affecting weld reliability. These data are now being used by others
to design new self-shielded welding electrodes with improved weld properties.
Probing the Subsurface with Electromagnetic Fields
Livermore researchers have been working with U.S. oil companies to improve
enhanced oil recovery technologies so that more oil can be extracted from
domestic production fields. One promising method is to inject carbon dioxide
underground to force more oil to the surface. A technique to view underground
fluids and gases, called crosswell electromagnetic imaging, is a valuable
tool for monitoring enhanced oil recovery operations. The technology provides
high-resolution images of underground deposits of oil, water, gas, and
other materials by measuring electrical resistivity or conductivity of
electrical current passing through different materials. The technique
is being tested by Lawrence Livermore researchers at a central California
oil field. The technology could be extended to monitoring underground
sequestration (long-term storage) of carbon dioxide from industrial operations,
a technique that is being explored to help the environment.
Probing the Liquid Water Surface
x-ray spectroscopy and a water microjet, researchers directly measured
the distances between neighboring oxygen atoms on the water's surface,
providing the first observation of the liquid surface relaxation.
New Targets for Inertial Fusion
are designing fusion fuel targets for two promising techniques for commercial
fusion power poduction.
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December 30, 2001