It promises a large-scale energy source on Earth, based on fuel extracted from water, and does not create the long-term waste that uranium-based nuclear fission does.
The option of generating energy from fusion reactions remains elusive, but ANU research has now provided a theory that explains a previously impenetrable problem.
When two or more smaller positively charged atomic nuclei come close enough they can fuse. In the process some of their mass is converted to energy, which could be harnessed.
However, for the charged atomic nuclei to overcome the electrostatic forces that push them apart first requires a great deal of energy, and while there have been many different concepts of how to generate fusion energy, in most cases they required more energy to initiate and contain fusion than was released in the reaction.
At present, magnetic confinement fusion based on the so called tokamak principle is considered to be the most promising approach,. Here strong magnetic fields are used to hold in place hydrogen heated until it is a plasma 10 times hotter than the centre of the sun for fusion reactions to 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.
In the 1980s, the US established the DIII-D research program which pioneered new technology including the use of beams of neutral particles to penetrate the confinement field of the device and heat the plasma within.
It is to date the largest fusion experiment in the US, although it also showed up the limitations of the technology.
Thus, the million-degree heating beams sometimes fail, and instead destabilise the fusion experiments before energy is generated.
“There was a strange wave mode which bounced the heating beams out of the experiment,” said Zhisong Qu, from the Australian National University (ANU), lead author of the research paper published in Physical Review Letters.
In the paper, Mr Qu and co-author Dr Michael Fitzgerald, from the Culham Centre for Fusion Energy in the UK, provide a theory for plasma behaviour based on fluid flow which can explain the unstable wave modes.
"This new way of looking at burning plasma physics allowed us to understand this previously impenetrable problem," said Mr Qu, a theoretical physicist. Dr Fitzgerald said the new method made much more sense than previous brute-force theories that had treated plasma as individual atoms.
“When we looked at the plasma as a fluid we got the same answer, but everything made perfect sense.”
According to ANU's research group leader Associate Professor Matthew Hole, the theory’s success with the DIII-D wave puzzle was just the beginning.
“It will open the door to understanding a whole lot more about fusion plasmas, and contribute to the development of a long term energy solution for the planet.”