It's been called the holy grail of sustainable energy - and now Kiwi technology could help bring nuclear fusion closer to reality.
Optical-fibre sensing technology developed and patented by Victoria University's Robinson Research Institute is set to be a key component in eagerly anticipated nuclear fusion-energy plants of the future.
The Robinson team has designed an early-warning system which can tell in milliseconds if the temperature of the magnets keeping the super-heated plasma inside a reactor is fluctuating beyond the system's design limits.
The superconducting magnets need to stay at super-cold temperatures, below -253C (20 degrees Kelvin) to generate a magnetic field strong enough to ensure the plasma stays contained inside a tokamak reactor.
A tokamak reactor is a donut-shaped chamber that confines and heats a gas plasma using electricity and magnetic fields.
These must operate continuously, or the power station will shut down, the lights will go off, and factories stop.
The Robinson optical-fibre early-warning system is part of the "VIPER" superconducting magnetic cable attached to the reactor.
Superconductors transport huge electric currents with close to no energy loss, allow incredibly high-current densities to be achieved and truly massive magnetic fields to be obtained.
The Robinson Institute specialises in work that combines innovative engineering and applied physics to build advanced, sustainable technologies for global benefit, including medical imaging, Maglev trains, motors, generators and electric propulsion systems for spacecraft.
Fusion power generates electricity by harnessing energy from nuclear fusion reactions like those in the centre of the sun, in which two lighter atomic nuclei, such as those of hydrogen, fuse at temperatures of more than 15 million degrees to form a heavier helium nucleus.
During the past 25 years or so, various institutes around the world have been working on reproducing those conditions. One way is with a tokamak reactor.
Robinson Institute deputy director and principal engineer Dr Rod Badcock, who is part of the VIPER cable development team, said the worldwide effort towards fusion power was led by the global ITER megaproject in France, where they are building a reactor "the size of a stadium".
"That has taken decades and tens of billions of dollars," he said.
"Around the time they started to plan for ITER was when high-temperature superconductivity was discovered. And the story with us starts then because it was the Robinson team which invented a patented and particular type of high-temperature superconductor.
"Coming forward 20 to 25 years, high-temperature superconductors are now a commercial reality. What several commercial companies now realise, including Commonwealth Fusion Systems (CFS) who we work with, is that if you can boost the magnetic field in the tokamak field to 20 Tesla instead of a few Tesla, the tokamak only needs to be a couple of metres in diameter and can fit inside a room.
"Instead of needing co-operation and budgets in tens of billions of dollars, and co-operations across governments and countries and continents, you can actually do it now as a private company."
Robinson's work is at the "heart of the containment of the plasma" he said.
"In the same way nobody would be happy if the Huntly Power Station turned off because the generator overheats, so too do the magnet coils in these reactors need constant monitoring.
"The superconducting magnets need to remain superconducting, and if anything starts to happen to jeopardise that, the operators need to know about it. That magnetic field needs to remain stable and the superconductor needs to remain superconducting.
"The technology we proposed was a unique cryogenic optical-fibre sensing technique that can sense anywhere down around the magnet if temperatures are starting to have very small fluctuations. For example, it allows us to see at 7 Kelvin (-266C) any temperature changes of around 1 Kelvin in order that they can keep the system running reliably.
"This system responds in milliseconds to any perturbation of the temperature anywhere around it. We now have a very, very early warning system, an incredibly sensitive technique that can be applied where you cannot put anything electrical.
"We demonstrated this under test conditions with CFS and CERN at the SULTAN facility in Europe, and we are doing that with an ongoing US programme. We have validated that this may be the only technology that could protect these systems under operating conditions."
The Robinson team is led by Badcock, engineer Mike Davies, PhD student Jofferson Gonzales and senior principal engineer Dr Huub Weijers.
Badcock said high-temperature superconductors have made fusion power reachable within the next 10 years.
"What we have achieved too is a very major part of fusion. Our contribution is our intellectual property and our work on the fibre sensing – there is no other technique that has worked like ours has.
"This is a great story, with the university working with MIT at the cutting edge of nuclear fusion and with CFS, one of the leaders in the field. We are also working alongside the Brookhaven National Laboratory and the Lawrence Livermore National Laboratory in the US.
"Robinson, of course, is recognised internationally as one of the leading places for the application of high-temperature superconductor technology and we have been sought out by the sustainable energy industry to work on their commercial programmes."