After 1.1 million hours of construction,
the fusion reactor Wendelstein 7-X is
ready to switch on.
Over 16 meters across, Wendelstein 7-X is the largest
example of a type of reactor known as a stellerator.
Like the more familiar tokamak reactors,
stellarators hold superhot gas in a cage
of powerful magnetic fields.
Wendelstein 7-X has been optimized
by a supercomputer to produce the best
possible magnetic cage.
50 bizarrely twisted superconducting magnets,
look more like sculptures,
than pieces of precision engineering.
They are cooled to minus 270 C and
operate just 1m away from the gaps at 100 million °C.
If Wendelstein 7-X can show it holds on to gas as well
as a tokamak, then stellarators may step into the limelight.
Building this complex machine has taken 19 years
but researchers hope when they turn
it on that it will recreate a little bit of the Sun
