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The WEST tokamak reactor has become the latest milestone in nuclear fusion research by generating and maintaining ultrahot plasmas. This is a significant advancement toward harnessing energy from hydrogen atom fusion, one of the cleanest and most highly efficient energy sources.
On February 12, the WEST tokamak in Cadarache, France, maintained the plasma for an all-time record of 1,337 seconds (22 minutes and 17 seconds). The plasma reached an astounding temperature of 50 million degrees Celsius (90 million degrees Fahrenheit) during the experiment, which is nearly three times the temperature of the core of the Sun.
Breaking Previous Records
The former record for the duration of plasma in a plasma-sustaining device was established by the Chinese EAST tokamak in January 2025, achieving 1,066 seconds (17 minutes and 46 seconds) of plasma operation. The most recent achievement at WEST, run by the Commissariat à l’énergie atomique et aux énergies alternatives (CEA), surpassed this duration by just 4 minutes and 29 seconds – for a total of 25% progress.
The advancement is rather crucial in developing nuclear fusion into an energy-generating technology. Future reactor power plants, including the one currently being constructed in southern France, the International Thermonuclear Experimental Reactor (ITER), will expect plasma holding for extensive periods.
“This leap forward demonstrates how our knowledge of plasmas and technological control of them over longer periods is becoming more mature and offers hope that fusion plasmas can be stabilized for greater amounts of time in machines such as ITER,” said a statement from the CEA.
How Nuclear Fusion Works
Nuclear fusion is the process that powers stars, including the Sun. If successfully harnessed on Earth, fusion would require fewer resources and less fuel than nuclear fission, which is currently used in nuclear power plants. Unlike fission, fusion does not generate long-lived radioactive waste, making it a cleaner energy source.
Nuclear fission produces energy by splitting atoms of heavy elements, whereas fusion does the opposite—it combines atoms of lighter elements to form heavier ones, releasing energy in the process. In the Sun’s core, hydrogen atoms fuse to create helium, the second-lightest element in the universe.
Replicating this process on Earth is extremely challenging. The Sun’s core maintains its fusion process at around 15 million degrees Celsius (27 million degrees Fahrenheit), where plasma remains confined due to the immense mass and gravitational force of the Sun.
Challenges of Achieving Fusion on Earth
As it happens, Earth isn’t that strong in gravity, unlike the Sun. Therefore, scientists apply a method known as magnetic confinement fusion, in which powerful magnetic fields are used to contain and heat plasma in a torus-like reactor until hydrogen atoms start to fuse.
To assist in compensating for the lack of gravity exerted by the Sun, tokamaks must attain temperatures greatly exceeding those found in the Sun’s core. ITER, for instance, will aim for the temperature of 150 million degrees Celsius (or 270 million degrees Fahrenheit), or an order of magnitude hotter than the Sun’s core.
These extreme temperatures must be maintained while achieving stability throughout the plasma. Furthermore, every material in the tokamak must cope with intense radiation without either itself being damaged or contaminating the plasma.
WEST’s Major Technological Milestone
“WEST has achieved a new key technological milestone by maintaining hydrogen plasma for more than twenty minutes through the injection of 2 megawatts (MW) of heating power,” said Anne-Isabelle Etienvre, Director of Fundamental Research at the CEA. “Experiments will continue with increased power. This excellent result allows both WEST and the French community to lead the way for the future use of ITER.”
The next phase of WEST’s research will focus on extending plasma duration even further, with the goal of sustaining it for several hours. Scientists will also work towards increasing the plasma temperature to levels required for practical fusion energy generation.
