On January 20, 2025, the Chinese experimental fusion reactor EAST set a new record for electron plasma confinement. The reaction was maintained for 1066 seconds, which is almost three times longer than the previous record. Almost all this time, the plasma temperature was around 100 million °C, which is six times higher than in the core of our star. The reactor recently completed another stage of modernization and is ready for new records.
Experimental Advanced Superconducting Tokamak outside. Image source: SCMP
The previous record was set by the EAST (Experimental Advanced Superconducting Tokamak or HT-7U tokamak) reactor, located in Hefei, Anhui Province, in April 2023. Then the thermonuclear reaction at the installation was maintained for 403 seconds with a plasma temperature of 100 million °C. Increasing the reactor runtime to 1000 seconds is considered key to achieving subsequent goals of both increasing the time to maintain the highest plasma temperature and raising the upper temperature limit.
Ultra-high temperatures are not needed to trigger a thermonuclear reaction in the Sun. The star’s core is “only” 15 million °C. To bring hydrogen ions closer together and trigger helium synthesis, the nuclei of atoms must come closer together until the strong nuclear interaction is activated, overcoming electrical repulsion. In addition to temperature, strong gravity helps in this – the mass of the Sun itself (this effect is also equivalent to pressure). On Earth, it is impossible to develop such pressure in a reactor chamber, so we have to “press” the nuclei by increasing the temperature. And the 100 million °C declared by Chinese scientists is not enough to start a reaction on Earth.
In all previous cases we were talking about the temperature of the electron plasma. Due to the records of Chinese fusion facilities, ion plasma has never been separately reported. At the same time, it is the ion plasma that needs to be heated to 100 million °C – these are nuclei devoid of electrons, which, in fact, enter into the fusion reaction. For some reason, the Chinese side is in no hurry to talk about records in heating ion plasma.
And yet, a new height level has been taken. For almost 18 minutes, the EAST reactor maintained a temperature of 100 million °C in the chamber. This is important both from the point of view of maintaining the stability of the installation (plasma), and from the standpoint of developing technologies and searching for new methods of working with the reactor, materials and other things, without which it is impossible to move forward.