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.

April 12, 2019

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A new light-based 3D printer replicates a model of Rodin’s “The Thinker” statue from a vial of resin. Photo by Adam Lau/UC Berkeley Engineering

Just a minute

About three years ago, Lawrence Livermore and UC Berkeley researchers had the idea to adapt the principles underlying the 3D imaging technique of computed tomography to create a rapid new 3D printing technique that could fabricate objects all at once.

This year, they've done just that. The process takes anywhere between 30 seconds and a couple of minutes to print an object.

The team was inspired by the widely used imaging technique of computed tomography, in which X-rays are projected through solid objects from many angles and software interprets the transmitted signals to build up a 3D image of what lies inside the object. Computed Axial Lithography (CAL) was conceived by turning the principles behind computed tomography on their head. It works by projecting a dynamically evolving pattern of light into a rotating volume of photosensitive material to form an object based on the cumulative dose of the illumination.

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Lawrence Livermore researchers found that the digestive system of the “horned passalus” beetle (Odontotaenius disjunctus) serves as a mini-reactor for biofuel production. Photo by Judy Gallagher

Nature’s own biorefinery

When most people think of wood-eating insects, they imagine termites that can destroy a home or business.

However, as part of a Lawrence Livermore bioenergy study, project scientist Jennifer Pett-Ridge and collaborators have learned how the digestive system of a wood-eating beetle serves as a natural mini-reactor for biofuel production.

Led by Javier Ceja-Navarro from Lawrence Berkeley National Laboratory, the team looked at the microorganisms living within the digestive tract of “horned passalus” beetles (Odontotaenius disjunctus), which live in fallen logs (harvested in Louisiana from fallen pecan tree logs) and are “subsocial” — living in colonies within the wood.

These beetles, which are common throughout the Eastern U.S., are responsible for decomposing a huge amount of wood and transforming it into soil organic matter, which contributes to the health and nutrient stock in forest soils. The fact that these beetles can live on food (wood) that is very poor quality — comprised mainly of lignin, cellulose and hemicellulose, with very little nitrogen — is thought to be linked to the capabilities of the bacteria and fungi that reside within their digestive system. 

“Understanding how the gut microbiome populations interact to deconstruct lignocellulosic materials to sugars or potential biofuels such as hydrogen and methane could potentially aid in the optimization of industrial cellulosic degradation,” said Pett-Ridge, an LLNL biogeochemist.

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Lawrence Livermore scientist Ate Visser sampling in the snow near Providence Creek.

It’s something in the water

Watersheds store water underground in soils and weathered bedrock. How long it takes for water to flow through the subsurface to feed streams is difficult to measure but important for understanding how watersheds function.

Lawrence Livermore researchers and their collaborators have studied the mixture of water ages in Providence Creek, a stream in the southern Sierra Nevada, California, using naturally occurring radioactive isotopes of hydrogen (tritium), sodium‐22 and sulfur‐35. The amount of these isotopes decreases because of radioactive decay as water spends more time underground. Each of these isotopes has a distinct half‐life (12.3 years, 2.6 years and 87 days, respectively). By using this combination of isotopes, the team was able to tease out the mixture of water ages in the stream.

This information helps scientists understand how the subsurface "selects" water from storage to generate streamflow. The researchers found that during dry conditions at Providence Creek, streamflow consists mainly of old groundwater, but during wet conditions it includes younger water.

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An illustration of the model used in the picosecond-pulse laser ablation studies. It shows a 1D version of the model along the central axis of the laser beam, which was utilized to study material response in isolation from 3D geometric effects.

In short order

By using ultrashort laser pulses, a team of researchers at Lawrence Livermore has found an efficient mechanism for laser ablation that could help pave the way to the use of lower-energy, less costly lasers in many industrial laser processing applications.

The method uses short-wavelength, high-fluence (energy per unit area) laser pulses to drive shockwaves that melt the target material. After the passage of the shockwave, the melt layer is placed under tension during a process known as relaxation, ultimately leading to the ejection of material through cavitation (unstable bubble growth).

The researchers used a combination of experiments and enhanced computer simulations in a range of laser energies and wavelengths to study ultrashort-pulse laser ablation of aluminum, stainless steel and silicon. Their findings show that ultraviolet picosecond pulses at fluences above 10 J/cm2 can remove more material with less energy than longer-wavelength pulse.

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Lab Report
L3-HAPLS — the world’s most advanced and highest average power, diode-pumped petawatt laser system — was designed, developed and constructed in only three years by Lawrence Livermore ’s NIF and Photon Science Directorate and delivered to ELI Beamlines in June 2017. Photo by Jason Laurea/LLNL

Open for business

The various petawatt-class laser systems at the ELI Beamlines facility near Prague bring to fruition the Nobel-winning vision of Gérard Mourou and Donna Strickland, a former Lawrence Livermore scientist.

The Extreme Light Infrastructure (ELI) project, a trio of giant laser facilities across eastern Europe, is officially up and running. Last year saw ELI pass several of its planned objectives on time and on budget as the sites become some of the world's foremost high-power laser user facilities.

The multi-sited endeavor comprises complementary facilities in the Czech Republic, Hungary and Romania, built to investigate light-matter interactions at the highest of intensities and the shortest of time scales currently possible. At its maximum output, the most powerful of the systems will be more than six orders of magnitude more intense than the prior state-of-the-art.

One of the lasers, the L3-HAPLS, is the world’s most advanced and highest average power, diode-pumped petawatt laser system. It was designed, developed and constructed in only three years by Lawrence Livermore’s NIF and Photon Science Directorate and delivered to ELI Beamlines in June 2017.