Malta scientists join effort to build machine that will recreate Sun’s energy

Fusion reactors would produce reliable electricity with virtually zero pollution

3 November 2016, 10:20am
By fusing deuterium and tritium, the reaction produces the highest energy gain at the “lowest” temperatures
By fusing deuterium and tritium, the reaction produces the highest energy gain at the “lowest” temperatures
Researchers at the University of Malta are contributing to the construction of the International Thermonuclear Experimental Reactor (ITER), a €20 billion nuclear fusion reactor known as a “tokamak”.

The reactor is being constructed in Cadarache, France, which will be the world’s largest machine of its kind.

The European Union, the United States, Russia, China, India, Japan and South Korea have all joined forces to build this experimental “magnetic confinement machine” that is set to prove the feasibility of nuclear fusion as a large-scale and carbon-free source of energy.

“It is based on the same principle that powers our sun and stars,” say the researchers at ITER. “ITER is designed to produce ‘net energy and maintain fusion reactions for long periods of time. It will be the first fusion device to test integrated technologies, materials and physics regimes necessary to build power plants for the commercial production of fusion-based electricity.”

The science is complex: ITER will fuse the hydrogen isotopes deuterium and tritium together. At extreme temperature, the energy being added to the gas will create a plasma, which will then be confined in the shape of a ring or torus, inside a chamber containing very strong superconducting magnets.

Fusion is the energy source of the sun and stars. In the tremendous heat and gravity at the core of these stellar bodies, hydrogen nuclei collide and fuse into heavier, helium atoms to release tremendous amounts of energy.

So by fusing deuterium and tritium, the reaction produces the highest energy gain at the “lowest” temperatures. But the conditions that must be fulfilled for this fusion include a very high temperature – 150 million degrees Celcius – and sufficient confinement time to hold the plasma, which tends to expand.

The reactor is being constructed in Cadarache, France
The reactor is being constructed in Cadarache, France
“ITER is designed to make the long-awaited transition from experimental studies of plasma physics, to full-scale electricity-producing fusion power stations,” researchers say.

The first plasma is expected to be produced by 2025.

Through a collaboration set up with the Paul Scherrer Institute (PSI) in Villigen Switzerland, Karl Buhagiar, Dr Ing. Nicholas Sammut (Deputy Dean, Faculty of ICT) and Dr Ing. Andrew Sammut (Dean, Faculty of Engineering) worked on the measurement and characterisation of the ITER Toroidal Field (TF) coils.

These coils are core main elements of the machine. In all there are 18 superconducting D-shaped coils, each measuring 13 metres by eight metres.

These coils are cooled to an unthinkable freezing -268°C in operating cryogenic conditions.

With an electrical current of 68,000 amperes, these superconducting coils carry about 2,000 times the current found in a standard household wire! And the currents generated will reach a peak magnetic field of 11.8 T, which is required to confine the plasma and control its shape and direction of movement inside the reactor chamber.

“Nuclear fusion reactions are very challenging to confine sustainably due to the extremely high temperatures involved. However, they release three times as much energy as current fission reactors, and their fuels are abundant. They also produce 100 times less radioactive waste that is not long lived,” researchers say.

“The design of tokamaks is also such that it would be impossible to undergo large-scale runaway chain reactions. If this technology is harnessed, fusion reactors would be able to produce reliable electricity with virtually zero pollution. Hence fusion power has the potential to provide sufficient energy to satisfy mounting demand and to do so sustainably with a relatively small impact on the environment.”