Newest Fusion Reactor Is a Relic of a Cold War Tech Rivalry

Plans left over from an unfinished Cold War tech rivalry could help meet the world’s clean energy needs.

Today, the Max Planck Institute in Greifswald, Germany, started up a nuclear fusion reactor using hydrogen fuel, the Associated Press reports. German Chancellor Angela Merkel, herself a former physicist, ceremoniously pushed the button. But the basic design of the new reactor is as old as the color TV.

IDL TIFF file
Photo of the plasma generated today in the Wendelstein 7-X.

Scientists have struggled to build a bug-free fusion reactor since the 1950s. The original Soviet model, a bagel-shaped device called a tokamak, is relatively simple to build and is the same design that underpins the massive ITER reactor under construction in France. Using powerful magnetic fields, the machine superheats hydrogen gas until it becomes plasma. At this point, the hydrogen atoms begin fusing into helium.

Not to be outdone by the Soviets, the Americans had their own fusion research program. Lyman Spitzer of Princeton University designed the American alternative in 1951. Dubbed the stellarator, the extra magnetic coils that wind their way around the outside of the tube keep the plasma fuel under better control, but they make for a much more complicated design.

So far, both models have had problems. For tokamaks, the plasma current tends to halt unexpectedly, causing powerful electric fields to escape and damage the reactor, and for stellerators,  construction costs have kept most on the drawing board. But the Planck Institute is giving the stellarator blueprint another shot.

The Institute’s reactor, called the Wendelstein 7-X, has been under construction since 1993—it was “hell on Earth” to build, the project’s leader told Science. The first test run was completed in December using helium fuel, which is easier to heat than hydrogen, the standard fuel. At today’s event, the Associated Press spoke to physics professor David Anderson of the University of Wisconsin, who was optimistic about that first test:

“The impressive results obtained in the startup of the machine were remarkable,” he said. “This is usually a difficult and arduous process. The speed with which W7-X became operational is a testament to the care and quality of the fabrication of the device and makes a very positive statement about the stellarator concept itself. W7-X is a truly remarkable achievement and the worldwide fusion community looks forward to many exciting results.”

Today’s test smashed hydrogen atoms together to produce superheated plasma—but only for a fraction of a second. The Wendelstein 7-X isn’t set up to provide power to northeastern Germany—it’s just testing the design for future reactors. It could be decades before stellarators replace other power sources.