Video screen shot of turbulence in the Alcator C-Mod tokamak

Video screen shot of turbulence in the Alcator C-Mod tokamak.

Courtesy of Nathan Howard.

Understanding the turbulence in plasmas

David L. Chandler  |  MIT News

A longstanding joke holds that practical fusion power is about 20 years away — and always will be.

One simple phenomenon explains why practical, self-sustaining fusion reactions have proved difficult to achieve: Turbulence in the superhot, electrically charged gas, called plasma, that circulates inside a fusion reactor can cause the plasma to lose much of its heat. This prevents the plasma from reaching the temperatures needed to overcome the electrical repulsion between atomic nuclei — which, in turn, prevents those nuclei from fusing together. But in order to tame that turbulence, scientists first must understand it.

Researchers at MIT’s Plasma Science and Fusion Center (PSFC) have now taken a significant step in that direction by quantifying a previously unknown type of small-scale turbulence that can have big effects on cooling the plasma in a reactor. Their results were published online in the journal Physics of Plasmas, and further described in a recent talk at a conference called the U.S.-E.U. Joint Transport Task Force Workshop.

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