Livermore scientists finally measure how diamond melts

Diamond doesn't melt like ice or metal. Under extreme pressure, scientists weren't even sure how it happened. Researchers at Lawrence Livermore National Laboratory just measured it directly for the first time. They compressed tiny diamond samples to pressures three times greater than Earth's core. The results, published in Nature Physics, fix a measurement that's been off for years.

Livermore uses diamond capsules to hold the fuel in its fusion experiments. A laser blast compresses the capsule until the fuel inside fuses, releasing energy. If the diamond melts unevenly, the whole implosion gets thrown off balance. The reaction then produces less energy than it should. Physicist Marius Millot, who led the study, says the new measurement lets his team time the laser shock more precisely. That alone could triple how much fusion energy comes out of a single shot. Other problems with the implosion still have to be solved first.

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Will this actually show up in a real fusion shot, not just a lab measurement? Livermore's National Ignition Facility already hit fusion ignition once, in 2022, producing more energy than the laser put in. That gives the lab a working baseline to test this against. The same measurement also tells physicists something about Neptune and Uranus, since both planets have interiors crushed to similar pressures.