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Fusion Failure Fixed

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Scientists have worked out why the beams they use to heat hydrogen gas to a plasma ten times hotter than the Sun sometimes destabilise their fusion experiments before energy is generated.

The solution, published in Physical Review Letters (www.tinyurl.com/hp6zn7d), used a new theory that treated plasma as a fluid rather than individual atoms.

Nuclear fusion of hydrogen into helium is the process that powers stars. It promises a large-scale energy source based on fuel extracted from water, and doesn’t create the long-term waste that uranium-based nuclear fission does.

The fusion experiments heat hydrogen gas until it becomes a plasma, and then use strong magnetic fields to hold it in place until fusion reactions occur. However, plasma this hot is extremely turbulent and can behave in surprising ways that baffle scientists, at times becoming unstable and dissipating before any fusion reactions can take place.

“There was a strange wave mode which bounced the heating beams out of the experiment,” said lead author Zhisong Qu, a PhD student at The Australian National University.

Qu developed a simpler theory for plasma behaviour based on fluid flow, and was able to explain an unstable wave mode that had been observed in the United States’ largest fusion experiment,...

The full text of this article can be purchased from Informit.