A New Experimental Fusion Reactor Powers Up in Germany

The reactor’s first test was brief but successful

Fusion reactor
Technicians hard at work are dwarfed by the Wendelstein 7-X stellarator Jens Büttner/dpa/Corbis

The quest to imitate the Sun—a.k.a. build a nuclear fusion reactor capable of producing abundant, sustainable energy—just took another step forward. Scientists at the Max Planck Institute for Plasma Physics in Greifswald, Germany turned on an experimental reactor and created hydrogen plasma for the first time, reports Frank Jordans for The Associated Press.

Fusion has been a kind of holy grail for physicists. If successfully harnessed, it could be a source of safe, clean nuclear energy. Instead of splitting atoms, as nuclear fission reactors do, fusion joins atoms, and hazardous radioactive waste is not produced.

"Everything went well today," Robert Wolf, a senior scientist involved with the project, tells Jordans at the AP. "With a system as complex as this you have to make sure everything works perfectly and there's always a risk."

The device in Germany is called the Wendelstein 7-X stellarator, reports David Talbot for MIT Technology Review. The stellarator is designed to contain plasma created by smashing together hydrogen atoms and blasting them with microwaves until the matter soars to temperatures of 100 million degrees, at which time the atoms' nuclei fuse to form helium. The whole process generates energy and mirrors what happens at the center of the Sun. In essence, the stellarator's donut-shape has to create a tiny star.

Yet fusion researchers aren't quite ready to power the world yet. Containing that star is the real challenge. Wednesday's experiment, by design, only created the plasma for a fraction of second before stopping to cool down. But that was long enough to hail the experiment as a success.

The stellarator uses a system of magnetic currents to contain the plasma, Talbot writes. Other devices are trying different approaches. In France, an international team is building a fusion reactor based on a device called a tokamak. This version is also donut shaped, but uses a strong electric current to trap the plasma. It's thought to be easier to build than a stellarator, but harder to operate. Other approaches include using magnetized rings and liquid metal pushed by pistons to compress and contain the plasma or  collide the atoms in a linear accelerator, reports M. Mitchell Waldrop for Nature

However, all of these devices are still decades away from commercial fusion power. That timeline, and the expense involved in developing the technology, has critics doubtful that the fusion energy dream is achievable. “I think these things are well motivated, and should be supported—but I don't think we're on the verge of a breakthrough," Stephen Dean, head of an advocacy group called Fusion Power Associates, tells Nature.

In the meantime, the stellarator in Germany will continue its inaugural test phase through mid-March, reports Jon Fingas for EnGadget. Then an upgrade will boost its capacity to run longer and heat hotter. Already the device has taken 19 years to build and cost about $1.3 billion, Fingas writes.

Hypothetically, the stellarator could run continuously. Their next goal is to keep the plasma stable for 30 minutes, though even that benchmark will take time to achieve. "If we manage 2025, that's good," Wolf tells the AP. "Earlier is even better." 

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