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Nachrichten, Termine, Experten
idw - Informationsdienst
Wissenschaft
On 10 December 2015, the nuclear fusion facility at the Max Planck Institute for Plasma Physics (IPP) in Greifswald generated its first plasma. Since then, the world's most powerful stellarator-type experiment has broken several records – and now forms the basis for power plant plans by several start-up companies.
Numerous international media representatives gathered in the control room at noon on 10 December 2015 to witness the launch of Wendelstein 7-X. In addition, several international fusion laboratories were connected live via video stream when the Wendelstein 7-X operating team fed one milligram of helium gas into the pumped-out plasma vessel for the first time and switched on the microwave heating. The first plasma appeared on built-in cameras. The measuring instruments recorded an input power of 1.3 megawatts, a temperature of one million degrees Celsius and a pulse duration of just one tenth of a second. The frenetic applause that erupted shortly afterwards lasted considerably longer.
Hundreds of employees at the IPP had worked towards this moment for years. The assembly of Wendelstein 7-X began in April 2005. A ring of 50 superconducting magnetic coils, each about 3.5 metres high, forms the core of the facility. They are cooled to temperatures of around minus 270 degrees Celsius. Calculating their complex shapes was only made possible by the use of supercomputers.
Wendelstein 7-X aims to prove that stellarators are suitable for power plants
The magnetic field encloses the hot plasma so that it floats largely contact-free in the doughnut-shaped plasma vessel. This is the principle behind magnetic fusion facilities, which until 2015 were mainly built according to the simpler tokamak principle. Wendelstein 7-X, on the other hand, belongs to the stellarators, which are more difficult to implement but have superior properties in theory.
But is the stellarator principle also suitable in reality for building a fusion power plant that, like the sun, generates energy from the fusion of hydrogen nuclei? Wendelstein 7-X aims to prove precisely this. To date, it is the most powerful stellarator experiment, used by researchers from all over the world.
‘We are starting with a plasma made from the noble gas helium,’ said IPP Director Thomas Klinger ten years ago. ‘This is because the plasma state is easier to achieve with helium. In addition, we can use helium plasmas to clean the surface of the plasma vessel.’ The first hydrogen plasma was ignited three months later by a prominent guest: Chancellor Dr Angela Merkel came to Greifswald on 3 February 2016 specifically to launch the scientific operation.
Temperatures of 40 million degrees Celsius are now being reached
Since then, Wendelstein 7-X has been upgraded in several phases of reconstruction. The vessel wall is now completely water-cooled and the plasma heating system is considerably more powerful. Wendelstein 7-X now achieves ion temperatures of 40 million degrees Celsius in the plasma.
In February 2023, plasma can be maintained for more than eight minutes for the first time – with an energy conversion of 1.3 gigajoules (coupled and decoupled energy). To date, this is the world record for stellarators. In the upcoming measurement campaigns, the Wendelstein 7-X team plans to increase these values significantly. The goal is a 30-minute pulse with high energy coupling. This would prove that stellarators are suitable for continuous operation.
In May 2025, Wendelstein 7-X achieved a new world record for the so-called triple product in long plasma discharges: on the last day of the measurement campaign, a new peak value for this key parameter in fusion physics was achieved over a plasma duration of 43 seconds. This puts the triple product on a par with the values achieved in the best tokamak experiments.
Start-ups orient themselves towards W7-X
The successes of Wendelstein 7-X have also inspired several newly founded companies around the world in recent years to develop stellarator power plants based on Wendelstein 7-X. In Germany, these are the companies Proxima Fusion and Gauss Fusion. The IPP is working with both of them within the framework of cooperation agreements.
Wendelstein 7-X is currently undergoing a one-year maintenance phase. In September 2026, the world's most powerful stellarator will resume experimental operation and set out to break records.
Contact:
Max Planck Institute for Plasma Physics
Frank Fleschner
Press officer
Boltzmannstraß 2
85748 Garching /Munich
https://www.ipp.mpg.de/17019/meilensteine
Maintenance work in the plasma vessel of Wendelstein 7-X in Greifswald (November 2025)
Copyright: MPI for Plasma Physics, Ben Peters
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