Tokamak Fusion Test Reactor. (Credit: Princeton Plasma Physics Lab/WikiCommons)

China’s cutting-edge nuclear fusion reactor has set a new world record after operating at 120 million Celsius for 101 seconds on May 28, according to the state-run newspaper the Global Times.

China’s largest and most advanced nuclear fusion experimental research device also achieved a peak temperature of 160 million Celsius, more than ten times hotter than the sun.

It is hoped the Experimental Advanced Superconducting Tokamak referred to as the ‘artificial sun’ due to the vast heat and power it produces, will produce a powerful green energy source.

The device, which is located in Anhui province and was first operated last December, broke its record of maintaining a plasma temperature of 100 million Celsius for 101 seconds.

It is designed to replicate the nuclear fusion process that occurs naturally in the sun and stars to provide almost infinite clean energy. Li Miao, Director of the Physics Department at the Southern University of Science and Technology in Shenzhen said the next aim is to run at a consistent temperature for a week.

“The breakthrough is significant progress, and the ultimate goal should be keeping the temperature at a stable level for a long time,” said Li Miao. The machine, which is based at the Hefei Institutes of Physical Science of the Chinese Academy of Sciences, uses a powerful magnetic field to fuse hot plasma.

Scientists have been working on developing smaller versions of the nuclear fusion reactor since 2006.

They plan to use the device in collaboration with scientists working on the International Thermonuclear Experimental Reactor (ITER) – the world’s largest nuclear fusion research project based in France, which is expected to be completed in 2025.

It is the largest global scientific cooperation effort since the creation of the International Space Station more than 20 years ago. South Korea Superconducting Tokamak Advanced Research has run at 100 million Celsius for 20 seconds.

Fusion is considered the Holy Grail of energy and is what powers the sun, which burns at roughly 15 million Celsius. It merges atomic nuclei to produce huge energy – the opposite of the fission process used in atomic weapons and nuclear power plants, which splits them into fragments.

Unlike fission, fusion emits no greenhouse gases and carries less risk of accidents or the theft of atomic material. But achieving fusion is both extremely difficult and prohibitively expensive, with the total cost of ITER estimated at £ 15.9 billion.

This is because causing hydrogen isotope atoms to collide and fuse to produce helium – the same way as the Sun creates energy – produces an enormous amount of waste heat.

However, last month UK scientists announced that they had found a way of dealing with these exhaust gases, cooling them from 150 million Celsius to just a few hundred degrees, temperatures similar to that of a car engine. This drastically reduces the wear and tear on the reactor in which the fusion occurs. Scientists at the UK Atomic Energy Authority, made their breakthrough using a £55 million experimental fusion reactor called MAST Upgrade.

At its heart is the tokamak, which uses a powerful magnetic field to confine the hydrogen isotopes into a spherical shape, similar to a cored apple, as they are heated by microwaves into plasma to produce fusion. The new divertor means long-promised nuclear fusion could be commercially viable in around 20 years, as UKAEA plans to build a £220 million scaled-up version of the MAST Upgrade by the 2040s.

What is a fusion reactor and how does it work?

Fusion is the process by which a gas is heated and separated into ions and electrons. It involves light elements, such as hydrogen, colliding to form heavier elements, such as helium.

For fusion to occur, hydrogen atoms are placed under high heat and pressure until they fuse. When deuterium and tritium nuclei – which can be found in hydrogen – fuse, they form a helium nucleus, a neutron and a lot of energy.

This is done by heating the fuel to temperatures over 150 million Celsius and forming a hot plasma, a gaseous soup of subatomic particles. Strong magnetic fields are used to keep the plasma away from the reactor’s walls so that it does not cool down and lose its energy potential.

These fields are produced by superconducting coils surrounding the vessel and by an electrical current driven through the plasma.
For energy production, plasma has to be confined for a sufficiently long period for fusion to occur. When ions get hot enough, they can overcome their mutual repulsion and collide, fusing.

When this happens, they release around one million times more energy than a chemical reaction and three to four times more than a conventional nuclear fission reactor.

Elham Asaad Buaras