The future of fusion

The future of fusion

Nuclear fusion could provide a virtually endless supply of energy with no carbon emissions and little radioactive waste, and scientists have devised an experiment with a half-ton doughnut-shaped magnet to move fusion a step closer.

Scientists at Massachusetts Institute of Technology have developed the Levitated Dipole Experiment – or LDX – with colleagues at the University of Columbia. A magnet – the size of a large truck tyre and made of superconducting wire coiled inside a stainless steel vessel – is used to control the motion of plasma contained within its 16-foot diameter outer chamber.

“It’s the first experiment of its kind,” said MIT senior scientist Jay Kesner, physics research group leader for LDX. He believes the experiment could produce an alternative path to fusion.

The experiment shows that random turbulence causes the plasma to become more densely concentrated, which is a crucial step towards getting atoms to fuse together. But Kesner warns that other fusion reactors like the tokamaks – which use a collection of coiled magnets surrounding a doughnut-shaped chamber to confine the plasma –are likely to go into production before LDX. More research is needed before deciding if the technology is practical – new equipment would be required to measure the temperature, and tests on a larger scale would be necessary.

The LDX magnet is supported by a magnetic field from an electromagnet overhead which is controlled by a computer based on precision monitoring of its position using laser beams and detectors. The magnet carries a current of one million amperes (compared with a typical home’s capacity of 200 amperes) and can be maintained this way to within half a millimetre. The magnet must be suspended in a magnetic field in this way because any supports would disturb the confinement of plasma.

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