China's EAST machine reaches temperatures six times hotter than the Sun

The reactor topped out at 100 million° C

Nuclear scientists at China's Institute of Physical Science are celebrating after their ‘artificial sun' - the Experimental Advanced Superconducting Tokamak (EAST) - reached 100 million° C - the minimum required to achieve nuclear fusion.

To put that in perspective, the Sun ‘only' reaches about 15 million° - meaning that, briefly, the plasma in EAST's reactor was six times hotter than our nearest star.

The massive amount of pressure inside the Sun forces tritium and deuterium isotopes (atomic variations of hydrogen) to fuse together, releasing tremendous amounts of energy. Nuclear fusion programmes like EAST are working to reach that state on Earth and harvest the energy produced, potentially providing an unlimited amount of clean energy.

Unlike nuclear fission, where the energy comes from the decay of large atoms into smaller elements, fusion releases very little waste: mostly helium.

However, because gravity is lower on Earth than it is inside the Sun, we need much higher temperatures and very precise control to force atoms to combine, and then to hold them in place while they produce energy.

One way of doing this is to inject plasma into a reactor and hold it in place with magnetic fields; tokamaks like EAST do this using the fields generated by the moving plasma itself. That makes it less stable than devices like stellarators, but also able to produce more heat (the record temperature for a stellarator, which Germany's Wendelstein 7-X reached this year, is 40 million° C).

The high temperatures inside a fusion reactor tear electrons away from their atoms and form a charged plasma of hydrogen ions. External magnetic coils contain the plasma to a small area to maximise the chances of fusion.

The Chinese team said that they achieved the record temperature using a variety of new techniques for heating and controlling the plasma, but could only maintain it for about 10 seconds.

Matthew Hole, a professor at the Australian National University, told ABC that the breakthrough will form an important contribution to the next major global experiment in nuclear fusion: the International Thermonuclear Experimental Reactor (ITER), which is under construction in southern France and is expected to begin operations in 2025.