Saturday, November 12, 2011

News From the World of Nuclear Fusion

A major upgrade to the DIII-D tokamak fusion reactor operated by General Atomics in San Diego will enable it to develop fusion plasmas that can burn indefinitely. Researchers installed a movable, 30-ton particle-beam heating system that drives electric current over a broad cross section of the magnetically confined plasma inside the reactor's vacuum vessel. Precise aiming of this beamline allows scientists to vary the spatial distribution of the plasma current to maintain optimal conditions for sustaining the high temperature plasmas needed for fusion energy production. _Eurekalert

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Physicists in San Diego have removed a stumbling block to sustained plasma fusion in tokamak reactors. This development should allow plasma fusion specialists to move ahead in their quest for essentially infinite energy.
The so-called "H-mode" where turbulence ceases and a tokamak becomes much more efficient was discovered as long ago as the 1980s, but working out how to make it happen - and keep happening, sometimes a tokamak will flick in and out of H-mode hundreds of times a second - has been difficult.

... The problem was that, until work began in San Diego, nobody really understood how and when turbulence ceased as surface flow built up. But Dr Lothar Schmitz and his crew are pleased to report that their method of using microwave radar guns - not dissimilar to police speed guns aimed into the torus using focusing mirrors - has given them a good handle on what's going on.

"We found that the turbulent eddies on the surface of the plasma produced surface flows that eventually grow large enough to shred the eddies, turning off the turbulence," says Schmitz. "Much like the population of predators and prey find a balance in the wild, we find that the plasma flow and the plasma turbulence reach an equilibrium in the tokamak plasma." _Register

Alan Boyle provides a nice overview on the state of the art of various approaches to fusion, including laser ignition, magnetic confinement, and assorted other types

Brian Westenhaus looks at news from the Bussard IEC fusion front

Gamma ray laser fusion technology has even been novelised recently by a Los Alamos scientist covers the unpredicatble developments in "cold fusion" or LENR -- low energy nuclear reactions

And Brian Wang's Nextbigfuture provides nice overall coverage of most large energy topics

The field of fusion is long past due for significant breakthroughs. When they begin coming, they may arrive too quickly to assimilate at once.

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