By IANS,
Washington : The prospect of fusion as a future power source is still decades away, but MIT scientists have edged closer to making it a reality.
Fusion has enormous potential because it produces no emissions, fuel sources are abundant and it produces relatively little (and short-lived) radioactive waste. But it still faces great hurdles.
“There’s been a lot of progress,” said physicist Earl Marmar, division head of the Alcator Project at the MIT Plasma Science and Fusion Centre (PSFC). “We’re learning a lot more about the details of how these things work.”
The Alcator C-Mod reactor, in operation since 1993, has the highest magnetic field and the highest plasma pressure of any fusion reactor in the world, and is the largest fusion reactor operated by any university.
One of the most vexing issues facing those trying to construct a fusion plant that produces more power than it consumes (something never achieved yet experimentally) is how to propel the hot plasma (an electrically charged gas) around inside the donut-shaped reactor chamber.
This is necessary to keep it from losing its heat of millions of degrees to the cooler vessel walls. Now, the MIT scientists think they may have found a way, said a MIT release.
Physicist Yijun Lin and principal research scientist John Rice have led experiments that demonstrate a very efficient method for using radio-frequency waves to push the plasma around inside the vessel, not only keeping it from losing heat to the walls but also preventing internal turbulence that can reduce the efficiency of fusion reactions.
“That’s very important,” Marmar says, because presently used techniques to push the plasma will not work in future, higher-power reactors such as the planned ITER (International Thermonuclear Experimental Reactor) now under construction in France, and so new methods must be found. “People have been trying to do this for decades,” he said.
Lin said that “some of these results are surprising to theorists,” and as yet there is no satisfying theoretical foundation for why it works as it does. But the experimental results so far show that the method works, which could be crucial to the success of ITER and future power-generating fusion reactors.”
“Lack of a controllable mechanism for propelling the plasma around the reactor “is potentially a showstopper,” Rice said, and the ITER team is “very concerned about this.”
“Given that the ITER project, which will take 10 years to build, is already underway, our results are just in time for this,” Lin said.
These results will appear in Physical Review Letters on Friday.