Another milestone towards nuclear fusion thanks to the Wendelstein 7-X experimental reactor

The International Thermonuclear Experimental Reactor (ITER) is the best-known nuclear fusion machine, but other fusion energy machines are also important, such as the Wendelstein 7-X experimental reactor located at the Max Planck Institute for Plasma Physics in Greifswald (Germany).

Completed in 2015 with a stellarator design, its purpose is to contribute to the development of technologies involved in the fine-tuning of nuclear fusion reactors using magnetic confinement. However, its model is different from those proposed in ITER or the JET reactor. The primary difference between tokamak reactors and stellarators lies in their geometry, as the former are toroidal (or doughnut-shaped) and the latter are more complex, resembling a twisted doughnut. Tokamaks require the magnetic fields that confine the plasma to be generated by coils and induced by the plasma itself, while in stellarators, everything is done with coils. There is no current inside the plasma, which means that stellarators are more complex and difficult to build.

Wendelstein 7-X successfully conducted its first tests between 2015 and 2018. Between November 2018 and 2022, it was modified to install a water cooling system capable of more efficiently removing residual thermal energy from the walls of the vacuum chamber, as well as a system that would allow the plasma to reach a higher temperature.

In February 2023, the reactor managed to confine and stabilise the plasma for 8 uninterrupted minutes, during which it delivered a total energy of 1.3 gigajoules, encouraging scientists to continue making changes and go further. As a result, they optimised the control and data acquisition systems and improved the plasma heating system, enabling it to generate more than 1 megawatt of power in the plasma through the application of microwaves (this technology is known as Electron Cyclotron Resonance Heating (ECRH)). and implemented nearly 50 additional diagnostic tests in addition to the usual ones.

A year later, the reactor was once again ready to carry out new experiments, and the first results were not long in coming. On 22 May, it sustained the fusion reaction using high-performance plasma for 43 seconds and delivered 1.8 gigajoules of energy, setting a new record on the road to achieving nuclear fusion.

News source: Max Planck Institute for Plasma Physics