Monday, August 25, 2014

World's largest laser compresses diamond to pressures of 50 million Earth atmospheres

Physicists in the US have compressed a synthetic diamond to pressures of 50 million Earth atmospheres to recreate conditions in the cores of giant planets.

A team of physicists at the Lawrence Livermore National Laboratory’s National Ignition Facilityin California have used the world's largest and most powerful laser to compress a synthetic diamond to pressures of 50 million times the Earth's atmosphere. This has allowed them to recreate the conditions found deep in the cores of gas giant and super-Earth planets for the first time.
To do this, they created a synthetic diamond, extracted a tiny, millimetre-sized sample of it, and zapped it with 176 high-powered fusion laser beams, half on the top of the sample, and half on the bottom. "Upon firing, the physicists measured the rate of diamond material moving under the tremendous heating and counter-reactions,” says Neomatica. "As the cylindrical piece of diamond is compressed, its middle bulges out at extremely high velocities. The measured peak velocity was 109,000 miles per hour, or about 45 kilometres per second.”
The team measured the peak pressure their diamond sample experienced to be 5 trillion pascals - or 5 terapascals - and at this point the density of the diamond had more than tripled, packing its mass into almost a quarter of the volume it had been in originally. This allowed the team to simulate how dense matter would behave in the incredible pressure within the cores of gas giants such as Jupiter, Saturn, Uranus and Neptune, and super-Earth planets outside the Solar System.
The team plans to use this technique to complete planet evolution models, and in future experiments, they will exert pressures on their diamond samples at 7 terapascals, which is thought to be the pressure in the deep centre of Jupiter. “[The study] paves the way for study of even more extreme environments," Neomatica reports, "for example at the centre of stars."

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