Researchers achieved promising results in double‑shell fusion experiments that promote a more uniform "volume burn." Adding a thin gold coating at an outer‑shell joint suppressed instabilities and produced nearly tenfold higher neutron yields than earlier double‑shell tests. The heavy inner shell helps scientists study material mixing, energy partitioning, and radiation behavior—insights relevant to both fusion development and astrophysics. Despite progress, challenges remain, including scaling, cost, and nuclear‑technology concerns.
Breakthrough Toward Scalable Fusion: 'Volume Burn' Achieved in Double‑Shell Experiments
Researchers achieved promising results in double‑shell fusion experiments that promote a more uniform "volume burn." Adding a thin gold coating at an outer‑shell joint suppressed instabilities and produced nearly tenfold higher neutron yields than earlier double‑shell tests. The heavy inner shell helps scientists study material mixing, energy partitioning, and radiation behavior—insights relevant to both fusion development and astrophysics. Despite progress, challenges remain, including scaling, cost, and nuclear‑technology concerns.
06:12 PM, 11/17/2025Science
Breakthrough Toward Scalable Fusion: 'Volume Burn' Achieved in Double‑Shell Experiments
Fusion—the process by which two light atomic nuclei combine to form a heavier nucleus—can release enormous amounts of energy without direct carbon emissions. That promise has driven decades of research into practical fusion power as a potential source of abundant, low-carbon electricity.
Researchers reported new progress with double‑shell implosion targets, an alternative to single‑shell designs that traditionally rely on igniting a central hot spot to launch a burn wave through the fuel. In double‑shell experiments, two concentric shells are used: an outer shell that directs energy inward and a dense inner shell that compresses the fusion fuel.
Co‑author Sasi Palaniyappan told the American Institute of Physics (AIP) that the double‑shell geometry can enable a more uniform "volume burn," "in which the fuel can ignite and burn more uniformly throughout its volume." More uniform ignition can improve burn efficiency and reduce destructive instabilities that have limited past experiments.
"The design enables what physicists call 'volume burn,' in which the fuel can ignite and burn more uniformly throughout its volume," — Sasi Palaniyappan, co‑author (reported by AIP)
Early double‑shell tests struggled with implosion instabilities, but the team discovered that adding a thin gold coating at the joint of the outer shell suppressed those disruptions. With that modification, neutron yields rose nearly tenfold compared with previous double‑shell attempts—an important step toward demonstrating the approach's potential.
The inner shell in these experiments was made from high‑atomic‑number metals. That choice helps scientists study how heavy elements mix into the fuel during implosion, how extreme temperatures and pressures distribute kinetic energy, and how radiation is trapped and reemitted. These diagnostics are valuable for both advancing fusion science and improving models of astrophysical phenomena.
Researchers emphasize that while these results are promising, significant challenges remain. Practical fusion power will require scaling, improved energy gain, reliable fabrication, and cost reductions. Experts also point to broader concerns associated with nuclear technologies—long‑term waste management, possible links to weapons proliferation, and high upfront capital costs—though fusion's waste and proliferation profiles differ from those of fission.
Looking ahead, Palaniyappan said further work will focus on increasing the efficiency of energy transfer between the shells and refining fabrication techniques. These experiments mark a meaningful step in exploring a potentially scalable path to cleaner, high‑power energy sources.