Daily Mail By ELLIE ZOLFAGHARIFARD 18 March 2016
- Iter uses electric current to trap plasma inside a doughnut-shaped device long enough for fusion to occur
- Engineers in France are currently building its 18 magnets that each weigh between 113,400kg and 226,800kg
- Rocket scientists have been recruited to create super-strong materials that can hold these magnets in place
- Construction of the nuclear reactor is expected to be completed by 2019 with trials starting as early as 2020
The International Thermonuclear Experimental Reactor (Iter) will be the world’s largest tokamak nuclear fusion reactor when it’s complete in 2019.
But its construction is proving a challenge.
A team of engineers in France is currently grappling with building the massive device, which has magnets that weigh as much as a Boeing 747.
A video released by the European Space Agency this week shows just how complex each component of the tokamak reactor is.
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It is being hailed as the ‘holy grail’ of energy – a device that could realise the dream of create limitless supplies of power. When it’s complete in 2019, Iter will be the world’s largest tokamak nuclear fusion reactor. Pictured is computer generated animation of what it’s interior could look like
It is being hailed as the ‘holy grail’ of energy – a device that could realise the dream of create limitless supplies of power. When it’s complete in 2019, Iter will be the world’s largest tokamak nuclear fusion reactor. Pictured is computer generated animation of what it’s interior could look like
Fusion involves placing hydrogen atoms under high heat and pressure until they fuse into helium atoms.
When deuterium and tritium nuclei – which can be found in hydrogen – fuse, they form a helium nucleus, a neutron and a lot of energy.
This is down by heating the fuel to temperatures in excess of 150 million°C, forming a hot plasma.
Strong magnetic fields are used to keep the plasma away from the walls so that it doesn’t cool down and lose it energy potential.
These are produced by superconducting coils surrounding the vessel, and by an electrical current driven through the plasma.
For energy production. plasma has to be confined for a sufficiently long period for fusion to occur.
Fusion works by using two kinds of hydrogen atoms — deuterium and tritium — and injecting that gas into a containment vessel.
Scientist then add energy that removes the electrons from their host atoms, forming what is described as an ion plasma, which releases huge amounts of energy.
If the technique is perfected, it would provide an inexhaustible source of power and potentially solve the world’s energy crisis.
ITER uses a strong electric current to trap plasma inside a doughnut-shaped device long enough for fusion to take place.
The device, known as a tokamak, was conceived by Soviet physicists in the 1950s. But it’s proving tough to build, and could be even tougher to operate.
Iter nuclear engineers have recruited rocket scientists to help create super-strong materials that can withstand temperatures hotter than the sun.
The Iter team claim a technique for building launcher and satellite components has turned out to be the best way for constructing rings to support the powerful magnetic coils inside the machine.
Spanish company CASA Espacio is making the rings using a method they have perfected over two decades of building elements for the Ariane 5, Vega and Soyuz rockets.
‘Forces inside ITER present similar challenges to space,’ explains Jose Guillamon, Head of Commercial and Strategy.
‘We can’t use traditional materials like metal, which expand and contract with temperature and conduct electricity.
‘We have to make a special composite material which is durable and lightweight, non-conductive and never changes shape.’
The magnets themselves are massive. Engineering & Technology reports that the one currently being built is 45 feet long, 30 feet wide, and 3 feet deep.
Now, the team is using a similar technique to build the largest composite structures ever attempted for a cryogenic environment.
With a diameter of 5 m and a solid cross-section of 30×30 cm, Iter’s compression rings will hold the giant magnets in place.
Nuclear fusion powers the sun and stars, with hydrogen atoms colliding to form helium while releasing energy.
It has long been a dream to harness this extreme process to generate an endless supply of sustainable electricity from seawater and Earth’s crust.
In a worldwide research collaboration between China, the EU, India, Japan, South Korea, Russia and the US, the first prototype of its kind is now being realised in Iter.
Construction is expected to be completed by 2019 for initial trials as early as 2020.
A commercial successor for generating electricity is not predicted before 2050.
Designed to generate 500 MW while using only a tenth of that to run, Iter aims to demonstrate continuous controlled fusion and, for the first time in fusion research, produce more energy than it takes to operate.
Eighteen ‘D’-shaped toroidal field magnets will surround the torus-shaped vacuum vessel to confine the plasma particles. Measuring 17 metres in height, 9 metres in width, and weighing in at 310 tons each, these coils rank among the largest components of the Iter machine.
Inherently safe with no atmospheric pollution or long-lived radioactive waste, one kilogram of fuel could produce the same amount of energy as 10,000 tonnes of fossil fuel.
At Iter’s core is a doughnut-shaped magnetic chamber, 23 m in diameter. It will work by heating the electrically charged gases to more than 150,000,000ºC.
Hotter than the sun, the plasma would instantly evaporate any normal container.
Instead, giant electromagnets will hold the plasma away from the walls by suspending it within a magnetic ‘cage’.
Now under construction, Iter’s rings will each withstand 7,000 tonnes – the equivalent of the Eiffel Tower pressing against each one of the six rings.
Carbon fibres are woven like fabric and embedded in a resin matrix to create a lightweight, durable and stable composite.
‘In the same way that you’d weave a different fabric for a raincoat than you would for a summer shirt, we can lay the fibres in different directions and alter the ingredients to adapt the resulting material to its role, making it extra strong, for example, or resistant to extreme temperatures in space,’ explains Jose.
For Iter, glass fibres are laid to maximise their mechanical strength and can be built up in slices and stacked like doughnuts to create the cylindrical structure.
