The quest to create nuclear fusion may have come a step closer after scientists heated solid matter to two million degrees Celsius with the world’s most powerful X-ray laser.
A team of researchers at the US Department of Energy’s Slac National Accelerator Laboratory in California carried out the experiments using rapid-fire laser pulses a billion times brighter than those of any X-ray source.
Scientists used those pulses to flash-heat a tiny piece of aluminium foil, creating what is known as “hot dense matter,” and took the temperature of this solid plasma – about 2 million degrees Celsius. The whole process took less than a trillionth of a second.
Slac said in a statement that the achievement takes scientists “a significant step forward” in understanding the most extreme matter found in the hearts of stars and giant planets, and could help experiments aimed at recreating the nuclear fusion process that powers the sun.
Gas-like plasma is often called the fourth state of matter after solids, liquids and gases. While uncommon on Earth, it makes up over 99 percent of the visible universe, including the interior of stars such as the sun.
“Making extremely hot, dense matter is important scientifically if we are ultimately to understand the conditions that exist inside stars and at the centre of giant planets within our own solar system,” said Sam Vinko, lead author of a report written by the Slac team.
Scientists have long been able to create electrically-charged plasma by heating gases, which can ripe away electrons from their atoms.
But up to now, no tools existed for doing the same thing at solid densities that cannot be penetrated by conventional laser beams.
The breakthrough should help understand – and perhaps one day recreate – nuclear fusion, long heralded as a potentially unlimited and clean source of energy, the researchers said.
There are currently two main paths towards making fusion energy.
One uses large-scale magnetic fields, the approach adopted by the International Thermonuclear Experimental Reactor (ITER) in France, set to become operational in 2019.
The National Ignition Facility in the US (NIF), by contrast, is one of several experimental facilities to use very high-energy optical lasers to achieve the same end.
