In a doughnut-shaped chamber in eastern China, scientists have been able to produce hydrogen gas more than three times hotter than the core of the Sun using nuclear fusion – and maintain this temperature for 102 seconds.
The breakthrough puts China one step ahead in the global race to harness a new, artificial kind of solar energy for clean and unlimited energy, the researchers claim. This has become a pressing concern as more of the earth’s natural reserves are rapidly depleting.
The experiment was conducted last week on a magnetic fusion reactor at the Institute of Physical Science in Hefei, capital of Jiangsu province, according to a statement on the institute’s website on Wednesday.
The reactor, officially known as the Experimental Advanced Superconducting Tokamak (EAST), was able to heat a hydrogen gas – a hot ionised gas called a plasma – to about 50 million Kelvins (49.999 million degrees Celsius). The interior of our sun is calculated to be around 15 million Kelvins.
According to this thermodynamic scale, absolute zero occurs at zero degrees (equivalent to minus 273.15 degrees Celsius), a point at which all molecular movement stops.
The temperature reached in Hefei was at the other end of the scale, and roughly the same as a mid-sized thermonuclear explosion. The goal of the experiment was to approximate the nuclear fusion conditions that occur deep inside the sun.
Although at least one other experiment in the last decade claims to have produced a hotter temperatures than this, it has never been duplicated and was unable to match the endurance – over one and a half minutes – of the Chinese test.
Meanwhile, physicists in Japan and Europe have been able to reach the same temperature as the Chinese team, but not for longer than a minute due to concerns of provoking a reactor meltdown.
The EAST was invented by Soviet scientists to control nuclear fusion for power generation.
As a tokamak device, it uses a powerful magnetic field to confine plasma in the shape of a torus – imagine a large spinning doughnut -for safety reasons due to the phenomenally high temperatures being generated. The atoms are effectively held floating in place by superconducting magnets.
But controlling hydrogen gas in such a hot and volatile state is a formidable challenge, and one that most of the tokomak devices built over the last 60 years have not been able to sustain for more than 20 seconds.
The scientists in Hefei worked “day and night” to achieve the record level of endurance, according to the institute, which serves as a subsidiary of the Chinese Academy of Sciences.
Lasers could heat materials to temperatures hotter than the centre of the Sun in only 20 quadrillionths of a second, according to new research.
Theoretical physicists from Imperial College London have devised an extremely rapid heating mechanism that they believe could heat certain materials to ten million degrees in much less than a million millionth of a second.
One of the problems with fusion research has been getting the energy from the laser in the right place at the right time. This method puts energy straight into the ions.
– Dr Arthur Turrell
The method, proposed here for the first time, could be relevant to new avenues of research in thermonuclear fusion energy, where scientists are seeking to replicate the Sun’s ability to produce clean energy.
The heating would be about 100 times faster than rates currently seen in fusion experiments using the world’s most energetic laser system at the Lawrence Livermore National Laboratory in California. The race is now on for fellow scientists to put the team’s method into practice.
Researchers have been using high-power lasers to heat material as part of the effort to create fusion energy for many years. In this new study, the physicists at Imperial were looking for ways to directly heat up ions – particles which make up the bulk of matter.
When lasers are used to heat most materials, the energy from the laser first heats up the electrons in the target. These in turn heat up the ions, making the process slower than targeting the ions directly.
The Imperial team discovered that when a high-intensity laser is fired at a certain type of material, it will create an electrostatic shockwave that can heat ions directly. Their discovery is published today in the journal Nature Communications.
“It’s a completely unexpected result. One of the problems with fusion research has been getting the energy from the laser in the right place at the right time. This method puts energy straight into the ions,” said the paper’s lead author, Dr Arthur Turrell.
Normally, laser-induced electrostatic shockwaves push ions ahead of them, causing them to accelerate away from the shockwave but not heat up. However, using sophisticated supercomputer modelling, the team discovered that if a material contains special combinations of ions, they will be accelerated by the shockwave at different speeds.
This causes friction, which in turn causes them to rapidly heat. They found that the effect would be strongest in solids with two ion types, such as plastics.
“The two types of ions act like matches and a box; you need both,” explained study co-author Dr Mark Sherlock from the Department of Physics at Imperial. “A bunch of matches will never light on their own – you need the friction caused by striking them against the box.”
“That the actual material used as a target mattered so much was a surprise in itself,” added study co-author Professor Steven Rose. “In materials with only one ion type, the effect completely disappears.”