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.

Nov. 18, 2022

Nature laser

Work, conducted at Lawrence Livermore National Laboratory shows that ions behave differently in fusion reactions than previously expected. Image by John Jett and Jake Long/LLNL.

Burning for you

Scientists who are working toward the dream of nuclear fusion, a form of power that could potentially provide abundant clean energy in the future, have discovered surprising and unexplained behavior among particles in a government laboratory. The results hint at the mysterious fundamental physics that underlie nuclear fusion reactions, which fuel the sun and other stars.

Researchers at the National Ignition Facility, a laser facility at Lawrence Livermore National Laboratory (LLNL), recently celebrated the milestone of creating what’s known as a “burning plasma,” which is an energized state of matter that is mostly sustained by “alpha particles” created by fusion reactions. The NIF also has reached the threshold of producing “ignition,” meaning fusion reactions that are self-sustaining, which is a major breakthrough, though it will likely still take decades to develop a fusion reactor—assuming it is possible at all.

Now, a team led by Ed Hartouni, a physicist at LLNL, has revealed that particles inside burning plasmas have unexpectedly high energies that could open new windows into the exotic physics of fusion reactors, which “could be important for achieving robust and reproducible ignition.”

NIF target

A target at the NIFincludes the cylindrical fuel container called a hohlraum. Photo by LLNL.

Magnets can create a bundle of energy

For scientists and dreamers alike, one of the greatest hopes for a future of bountiful energy is nestled in a winery-coated valley east of San Francisco. 

Inside Lawrence Livermore’s National Ignition Facility’s boxy walls, scientists are working to create nuclear fusion, the same physics that powers the sun. About a year ago, NIF scientists came closer than anyone to a key checkpoint in the quest for fusion: creating more energy than was put in.

Recent research might bring them one step closer to cracking a problem that has confounded energy-seekers for decades. Their latest trick: lighting up fusion within the flux of a strong magnetic field. 

Tests with other lasers, like OMEGA in Rochester, New York, and the Z-machine in Sandia, New Mexico — had shown that this method could prove fruitful. Moreover, computer simulations of NIF’s own laser suggested that a magnetic field could double the energy of NIF’s best-performing shots. 

“Pre-magnetized fuel will allow us to get good performance even with targets or laser delivery that is a little off of what we want,” said LLNL physicist John Moody, who is involved in the research.

titanium stress

in a recent study by a multi-national team, including current and former LLNL scientists, researchers used synchrotron X-rays to track discrete slip avalanche events in titanium held under load at room temperature to examine causes of “dwell fatigue” in titanium alloys.

Tracking fatigue in titanium

"Dwell fatigue" is a phenomenon that can occur in titanium alloys when held under stress, such as a jet engine’s fan disc during takeoff. This peculiar failure mode can initiate microscopic cracks that drastically reduce a component's lifetime.

The most widely used titanium alloy, Ti-6Al-4V, was not believed to exhibit dwell fatigue before the 2017 Air France Flight 066 incident, in which an Airbus en route from Paris to Los Angeles suffered fan disc failure over Greenland that forced an emergency landing. The analysis of that incident and several more recent concerns prompted the Federal Aviation Administration and European Union Aviation Safety Agency to coordinate work across the aerospace industry to determine the root causes of dwell fatigue.

According to experts, metals deform predominantly via dislocation slip — the movement of line defects in the underlying crystal lattice. Researchers hold that dwell fatigue can initiate when slip is restricted to narrow bands instead of occurring more homogenously in three dimensions. The presence of nanometer-scale intermetallic Ti3Al precipitates promotes band formation, particularly when processing conditions allow for their long-range ordering.

In a recent study by a multi-national team, including current and former Lawrence Livermore scientists, researchers used synchrotron X-rays to track discrete slip avalanche events in titanium held under load at room temperature.

SJEYH

LLNL Director Kim Budil served as the keynote speaker, inspiring more than 250 attendees at the 30th annual San Joaquin Expanding Your Horizons conference in Stockton.

Record.net

STEM goes to Stockton

Purple shirts overflowed the De Rosa University Center at the University of the Pacific earlier this month for the San Joaquin Expanding Your Horizons conference. The event aims to inspire girls and share insight into the science and mathematics world. 

Ubiquitous Electronics, Amazing Everyday Chemistry and Chemistry Behind Winemaking were just some of the 15 different workshops offered this year at the conference for girls interested in science, technology, engineering and math (STEM).  

More than 300 girls in purple shirts from San Joaquin County schools in grades 6-12 attended this year's conference. 

“These kinds of programs can be life-changing,” said Kim Budil, director of Lawrence Livermore National Laboratory, which co-sponsors the conference.  

nuclear force

Radial-plane cross-sectional view of the BPT showing a typical triple event. Image courtesy of Physical Review Letters.

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The force is weak here

The weak nuclear force is currently not entirely understood, despite being one of the four fundamental forces of nature. In a pair of Physical Review Letters articles, a multi-institutional team, including theorists and experimentalists from Louisiana State University (LSU), Lawrence Livermore National Laboratory, Argonne National Laboratory and other institutions worked closely together to test physics beyond the “Standard Model” through high-precision measurements of nuclear beta decay.

By loading lithium-8 ions, an exotic heavy isotope of lithium with a less than one second half-life, in an ion trap, the experimental team was able to detect the energy and directions of the particles emitted in the beta decay of lithium-8 produced with the ATLAS accelerator at Argonne National Laboratory and held in an ion trap. Different underlying mechanisms for the weak nuclear force would give rise to distinct energy and angular distributions, which the team determined to unrivaled precision.

State-of-the-art calculations with the ab initio symmetry-adapted no-core shell model, developed at Louisiana State University, had to be performed to precisely account for typically neglected effects that are 100 times smaller than the dominant decay contributions. However, since the experiments have achieved remarkable precision, it is now required to confront the systematic uncertainties of such corrections that are difficult to be measured.

The results are essential for improving the sensitivity of high-precision experiments that probe the weak interaction theory and test physics beyond the Standard Model. Grigor Sargsyan led the theoretical developments while he was a Ph.D. student at LSU, and is currently a postdoctoral researcher at Lawrence Livermore.

lab panorama

LLNL Report takes a break

The LLNL Report will take a break for the Thanksgiving holiday. It will return Dec. 2, 2022.