Lab Report

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The Lab Report is a weekly compendium of media reports on science and technology achievements at Lawrence Livermore National Laboratory. Though the Laboratory reviews items for overall accuracy, the reporting organizations are responsible for the content in the links below.

Feb. 28, 2020

fuel injector

A fuel injector simulation created using the Sierra supercomputer at LLNL. Image courtesy of GE Research.

3D printing hits the gas

A team at GE Research had other plans in mind when the U.S. Department of Energy selected a GE project among 47 winners in the 15th year of its Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. The project? Find new methods for optimizing jet engine and power generation efficiency with 3D printing.

The INCITE program allows science and engineering projects to use some of the country’s powerful supercomputers from such labs as Lawrence Livermore to perform advanced calculations, simulations and other operations, with the goal of making new scientific and technological discoveries.

Previous work with the Sierra supercomputer at Lawrence Livermore National Laboratory allowed GE to test simulations of fuel injectors, which are difficult to test physically. Supercomputer simulations therefore make it possible to reduce the number of trials required to test them.

NIF

The preamplifiers of the National Ignition Facility are the first step in increasing the energy of laser beams as they make their way toward the target chamber. NIF recently achieved a 500-terawatt shot - 1,000 times more power than the United States uses at any instant in time.

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Reaching for the stars

Fusion is the process that powers the sun and the stars. It occurs when the nuclei of two atoms are forced so close to one another that they combine into one, releasing energy in the process. If the reaction can be tamed in the laboratory, it has the potential to deliver near-limitless baseload electricity with virtually zero carbon emissions.

The easiest reaction to initiate in the laboratory is the fusion of two different isotopes of hydrogen: deuterium and tritium. The product of the reaction is a helium ion and a fast-moving neutron.

LLNL’s National Ignition Facility has attempted to achieve hydrogen-deuterium fusion ignition using 192 laser beams focused on a small target. These experiments reached one-third of the conditions needed for ignition for a single experiment. The challenges include precise placement of the target, non-uniformity of the laser beam and instabilities that occur as the target implodes.

neutral
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Getting to zero

A new study from Lawrence Livermore National Laboratory evaluates strategies to achieve former Gov. Jerry Brown's goal of carbon neutrality by 2045. Unlike other reports that study emission reductions, it evaluates "negative emissions" strategies.

Carbon neutrality, or net-zero emissions, applies to all sources of greenhouse gas emissions. But just what does achieving carbon neutrality require, and is it even possible?

The LLNL study reports that California can reach carbon neutrality by 2045, "and achieve and maintain net negative emissions thereafter." The report does not consider emissions reductions strategies, such as using renewable energy, driving electric vehicles or walking. Emissions not eliminated would be offset,  but not by purchasing carbon offsets.

According to the report, “The most immediate path to achieve carbon neutrality may be to offset the residual emissions by negative emissions, which uses either natural or man-made means to remove CO2 from the atmosphere.”

“Our findings give us confidence that this combination of negative emissions technologies and the state’s existing ambitions put the finish line in reach for California,” said Roger Aines, LLNL’s Energy Program chief scientist and the lead on the project.

glacier melt
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Climate on thin ice

Tropical glaciers in Africa and South America began their retreat simultaneously at the end of the last ice age about 20,000 years ago, according to a recent study by a multi-institutional research team that includes Lawrence Livermore National Laboratory’s (LLNL) Susan Zimmerman.

The finding of synchrony in ice retreat across the global tropics clarifies how the low latitudes transformed during one of Earth’s most extreme climate-change events, and can help current-day predictions of the planet’s climate future.

According to the study, glaciers in the tropics of Africa and South America reached their maximum extents between 29,000 and 21,000 years ago and then began to melt. This retreat is earlier than the significant rise in atmospheric carbon dioxide recorded at about 18,200 years ago. The findings demonstrate a trend of increasing temperatures across the tropics and suggest that the warming may have been caused by a reduction in the temperature differences between the Earth’s polar regions and the tropics.

The study supports the overwhelming scientific consensus on the role of carbon dioxide in causing global climate change, but adds additional levels of complexity to the understanding of Earth’s climate system and how ice ages rapidly end. The result also adds to the understanding of the sequencing of glacial retreat between the tropics and the polar regions at the time.

target

This photo of a compound parabolic concentrator (CPC) assembly shows the cone-shaped, 1-millimeter gold CPC attached to a 500-micron-thick gold foil. Between the cone and the foil is a plastic support. Credit: Rick Heredia.

That’s intense

Lawrence Livermore engineers devise compound parabolic concentrators that increase a laser’s intensity so that the laser can accelerate particles to experience the effects of relativity. These contractors, essentially special targets, let researchers expand the experimental capabilities of the National Ignition Facility’s (NIF) Advanced Radiographic Capability (ARC) laser. In effect, it lets the ARC laser create effects associated with laser intensities more than 10 times greater than it was designed to deliver.

“The results are significant because it means we can do experiments on ARC that we didn’t think we’d be able to,” says LLNL physicist Andrew MacPhee.

ARC is a powerful short-pulse laser that was designed to operate at about 1018 W/cm2 (1 quintillion watts per square centimeter) on target. However, to accelerate field particles to a significant fraction of the speed of light and see relativistic effects requires considerably more intensity. So, the research team’s goal was to concentrate the energy of ARC’s four beamlets when they arrive during picosecond-scale events inside the target chamber.