It
is being hailed as the 'holy grail' of energy - a device that could realize the
dream of create limitless supplies of power.
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.
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.
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
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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.
The
final design will use 18 of these magnets, each weigh between 113,400kg and
226,800kg (250,000 and 500,000lbs)—which is about the same as a Boeing 747
airplane.
CASA
Espacio has been at the forefront of developing a technique for embedding
carbon fibres in resin to create a strong, lightweight material to hold these
magnets.
The
composite is ideal for rocket parts because it retains its shape and offers the
robust longevity needed to survive extreme launches and the harsh environment
of space for over 15 years.
Now,
the team is using a similar technique to build the largest composite structures
ever attempted for a cryogenic environment.
With a diameter of 5m and
a solid cross-section of 30x30 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 realized
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 500MW 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.
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, 23m 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 maximize their mechanical strength and can be built up in slices and
stacked like doughnuts to create the cylindrical structure.
Construction
is expected to be completed by 2019 for initial trials as early as 2020. The
new magnet will form part of ITER's first Toroidal Field coil (pictured under
construction)
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Originally published in Mail Online UK
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