Our Sun is a gigantic fusion device,
the biggest in our solar system.
of hydrogen into helium
On the Sun, due to the strong gravity, hydrogen atoms fuse at 15 million°C. On Earth, however, because of the weaker gravitational forces, they need to be heated at temperatures as high as 150 million °C in order to collide
They came up with the idea of a Tokamak: a chamber using a powerful magnetic field to contain the hot plasma.