LAB REPORT

Lawrence Livermore scientists announced this week that they have taken an important step in the long trek toward making nuclear fusion — the very process that powers stars — and a viable energy source for humankind.

Using the world's largest laser, the researchers coaxed fusion fuel for the first time to heat itself beyond the heat they zapped into it, achieving a phenomenon called a burning plasma that marked a stride toward self-sustaining fusion energy.

The experiments produced the self-heating of matter in a plasma state through nuclear fusion, which is the combining of atomic nuclei to release energy. Plasma is one of the various states of matter, alongside solid, liquid and gas.

"If you want to make a camp fire, you want to get the fire hot enough that the wood can keep itself burning," said Alex Zylstra, an LLNL experimental physicist. "This is a good analogy for a burning plasma, where the fusion is now starting to become self-sustaining."

Solid electrolytes may overcome key technological hurdles associated with the narrow electrochemical and thermal stability of conventional lithium (Li)-ion and sodium (Na)-ion batteries.

However, many solid electrolytes — ceramics in particular — also suffer from poor cycling issues and limitations in their ability to efficiently transport ions. These limitations often stem from interfaces and other features that make up the microstructure of the material, which in turn depends on how it is processed.

Lawrence Livermore scientists, in collaboration with San Francisco State University and Penn State, have developed a broad suite of multiscale simulation capabilities to help identify, assess and overcome microstructural impacts on ion transport in solid electrolytes.

The melting point of iron has been measured in conditions similar to those found in the cores of super-Earths, planets with masses several times that of our world.

A molten iron core is a feature of many planets, including Earth. On Earth, the molten core is responsible for generating a magnetosphere: a spherical magnetic field that shields the planet from radiation and allows life on the surface to survive. Understanding the conditions under which iron melts, or stays solid, can tell us how likely it is that other types of planets will be similarly protected with a magnetosphere, and for how long.

Richard Kraus at the Lawrence Livermore National Laboratory and his colleagues used one of the world’s most energetic lasers, at the Lab’s National Ignition Facility, to recreate the pressures found at the centre of super-Earths. They then used diffracted X-rays to work out whether iron would be solid or liquid under these conditions.

New research conducted at Lawrence Livermore explores the expansion of a classical mechanics model that has been useful for understanding asymmetries in inertial confinement fusion (ICF) implosions, from a two-piston to a six-piston model to capture higher-mode asymmetries.

Omar Hurricane, chief scientist for the LLNL ICF program, said the research shows that the key asymmetry that degrades performance in an ICF implosion is the asymmetry of the shell areal density at stagnation and that the key mathematical quantity that captures the important physics

It also shows that the radius at which the implosion acquires its peak velocity has a very strong impact on fusion performance and it has a direct connection to the concept of "coast time.”

"Asymmetry wastes kinetic energy in an implosion — we call this RKE or residual kinetic energy," Hurricane explained. "The less kinetic energy available to the implosion, the lower the fusion performance. Minimizing asymmetry in our ICF implosions has been a struggle because it integrates asymmetry present in the targets — the capsules in particular, the laser and the X-ray radiation field in the hohlraum."

The Earth — with its myriad interactions of atmosphere, oceans, land and ice components — presents an extraordinarily complex system for investigation.

For researchers, simulating the dynamics of these systems has presented a process that is just as complex. But today, Earth system models capable of weather-scale resolution take advantage of powerful new computers to simulate variations in Earth systems and anticipate decade-scale changes that will critically impact the U.S. energy sector in coming years.

Scientists at Lawrence Livermore are part of a team that developed Version 2 of the Energy Exascale Earth System Model (E3SMv2). Released to the scientific community in late September, the model runs more than two times faster than its predecessor (E3SMv1).

“E3SMv2 allows us to more realistically simulate the present, which gives us more confidence to simulate the future,” said David Bader, a LLNL scientist and overall lead of the E3SM project.