When It Comes to Fusion, Materials Matter

Fusion, the process that powers the sun, holds promise for generating abundant and reliable energy on Earth. Controlling fusion reactions, however, has additional benefits. The process generates subatomic particles called neutrons that find applications in medicine, research, and national security. Scientists at the University of California, Davis (UC Davis) and Lawrence Berkeley National Laboratory (Berkeley Lab) have discovered that materials surrounding a fusion reaction can significantly enhance its frequency, especially at low energies where fusion is rare.

Their study, published in Nature Communications on July 18, presents a new approach to studying and engineering nuclear reactions within solid materials. This innovative field, dubbed "materials-driven fusion," could potentially lead to more compact and efficient neutron generators with wide-ranging applications, such as cargo screening, planetary science, medical therapy, and imaging.

The researchers used palladium and titanium foils to encapsulate deuterium, a heavy form of hydrogen atoms commonly employed in fusion. By firing deuterium ions at these foils at varying energies and measuring the resulting fusion rates, they discovered that the materials surrounding the fusion reaction could considerably boost its occurrence. Notably, the effect was most pronounced at low energies, below 2.5 kiloelectronvolts, where fusion rates typically plummet.

The team observed a surprising plateau in fusion rates at these low energies, with some samples exhibiting rates roughly a quintillion times higher than bare fusion reactions. While the exact mechanism behind this phenomenon remains unclear, the researchers speculate that electrons and defects within the materials might partially shield repulsive electrostatic forces between deuterium nuclei, facilitating their proximity and fusion possibility.

By understanding and manipulating the electronic structure, defects, and composition of materials, researchers could potentially enhance nuclear reactions.

Jeremy Munday, a professor at UC Davis and corresponding author of the study, emphasized the importance of further investigating the underlying mechanism to determine the limits of this enhanced fusion. "Understanding this effect better opens the door to engineering new materials that would affect the fusion rate under certain conditions," he stated.

The team plans to explore a broader range of materials and continue investigating the unexpected fusion plateau at lower energies. This work not only validates the material environment's active role in low-temperature fusion but also establishes a reproducible experimental platform to study the interplay between solid materials and nuclear reactions, bridging fusion science, materials science, and chemistry.