Transmission electron microscope (TEM) images of shock-induced defects in diamond samples. Credit: Boya Li

Scientists at the University of California San Diego have uncovered how diamond—the material used to encase fuel for fusion experiments at the National Ignition Facility (NIF) in Lawrence Livermore National Laboratory—can develop tiny structural flaws that may limit fusion performance.

At the NIF, powerful lasers compress diamond capsules filled with deuterium and tritium to the extreme pressures needed for nuclear fusion. This process must be perfectly symmetrical to achieve maximum energy output.

By using a high-power pulsed laser to simulate these extreme conditions, researchers found that diamonds can form a series of defects, ranging from subtle crystal distortions to narrow zones of complete disorder, or amorphization. These imperfections can disrupt the implosion symmetry, which in turn can reduce energy yield or even prevent ignition.

The findings can help guide improved capsule designs and models to achieve more uniform implosions, and thus maximize the energy output of fusion experiments. The work brings researchers a step closer to harnessing fusion as a practical energy source.

The study, published in Matter, was led by UC San Diego researchers Boya Li and Marc Meyers.

More information: Boya Li et al, Direct observation of plastic deformation in diamond under extreme loading, Matter (2025). DOI: 10.1016/j.matt.2025.102271

News from: https://phys.org/news/2025-08-weak-diamond-fusion-fuel-capsules.html