Lab recreates extreme conditions that may produce diamond rain on Neptune and Uranus
Researchers at Lawrence Livermore National Laboratory used the Omega Laser Facility to vaporize a diamond sample, generating shock waves that compressed it to pressures over three times Earth's core and temperatures near the sun's surface for a billionth of a second. The experiment resolved a 20-year discrepancy between measured and quantum-mechanically predicted diamond melting points, differing by about 1,000 kelvins. The findings also suggest the same physics could help triple fusion energy output.
The experiment employed X-ray diffraction to capture diamond's phase transition in real time, revealing that solid diamond is less dense than liquid metallic carbon—a relationship analogous to ice floating on water. This unexpected property helps explain how diamond raindrops could form and descend through the deep interiors of ice giants, contributing to Neptune's excess heat output.
The findings also carry implications for fusion research. The same physics governing diamond's behavior under extreme compression may inform strategies to triple fusion energy yield. Additionally, the new data resolved a long-standing discrepancy between theoretical quantum models and experimental measurements, validating computational approaches that previously appeared inconsistent with physical observations.
This research could deepen understanding of planetary formation and energy dynamics, potentially refining models used in astrophysics and materials science. The fusion energy connection may offer a pathway toward more efficient clean power generation, though commercial viability remains distant. Society could benefit from accelerated fusion research and improved planetary modeling, while the dramatic imagery of diamond rain may enhance public engagement with fundamental science.