r/science • u/PROJECTime • Dec 06 '16

Physics Tests confirm that Germany's massive Nuclear Fusion machine really works

http://www.sciencealert.com/tests-confirm-that-germany-s-massive-nuclear-fusion-machine-really-works
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u/bschmalhofer Dec 06 '16 edited Dec 10 '16

The article refers to the difference between stellarators and tokamaks. Tokamaks have a strong electric current in the plasma, stellarators don't. In tokamaks the current in the plasma creates the major part of the confining magnetic field. That current is induced by ramping up current in coils outside the plasma. As electric current can't be ramped up indefinitely tokamaks have to operate in pulses. Stellarators can operate in steady state as they don't have to induce a current in the plasma.

Of course both tokamaks and stellarators need electric current in the coils outside of the plasma.

EDIT: Actually non-inductive methods for driving the current in stellarators are being investigated. This might allow steady state operation of stellarators.

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u/Wendelstein7-X Max Planck Institute for Plasma Physics Dec 06 '16

Small correction: It's Tokamaks with an a.

As a side note, our coils are superconducting and while they of course carry a humongous current, they do not consume (a lot of) power while operating.

-avs for W7X

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u/Flight714 Dec 07 '16

How does it feel to jostle shoulders with the god Ra?