The Germans have built a Stellarator

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For more than 60 years, scientists have dreamed of a clean, inexhaustible energy source in the form of nuclear fusion. And they’re still dreaming.

But thanks to the efforts of the Max Planck Institute for Plasma Physics, experts hope that might soon change. Last year, after 1.1 million construction hours, the institute completed the world’s largest nuclear fusion machine of its kind, called a stellarator.

They call this 16-metre (52-foot) wide machine the W7-X. And following more than a year of tests, engineers are finally ready to fire up the US$1.1 billion machine for the first time, and it could happen before the end of this month, Science reported.

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For years, tokamaks have been considered the most promising machine for harnessing the power of the sun because the configuration of their magnetic coils contains a plasma that is better than that of currently operational stellarators.

But there’s a problem: Tokamaks can only control the plasma in short bursts that last for no more than 7 minutes. And the energy necessary to generate that plasma is more than the energy engineers get from these periodic bursts.

Tokamaks thus consume more energy than they produce, which is not what you want from nuclear fusion reactors, which have been touted as the “most important energy source over the next millennium.”

Because of the stellarators’ design, experts suspect it could sustain a plasma for at least 30 minutes at a time, which is significantly longer than any tokamak. The French tokamak “Tore Supra” holds the record: 6 minutes and 30 seconds.

If W7-X succeeds, it could completely turn the nuclear fusion community on its head and launch stellarators into the lime light.

“The world is waiting to see if we get the confinement time and then hold it for a long pulse,” David Gates, the head of stellarator physics at the Princeton Plasma Physics Laboratory, told Science.

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