From the stars to the Earth

Fusion is the source of energy in the sun and other stars. A star starts to shine when, under the force of gravity, the matter in its very heart attains sufficiently high densities and temperatures to set off thermonuclear reactions, which then release energy. Plasma’s tendency of dispersing, and therefore cooling down, is balanced out by gravitational force.

On Earth, gravitational confinement is impossible. Two paths have been studied to reproduce these reactions:

• raising a small volume of matter for a very short time to very high pressure and temperature, described as inertial confinement. We thus seek to obtain the greatest possible number of fusion reactions before the plasma disperses.

• trapping and maintaining a plasma at very high temperature. This plasma is confined in an intangible torus-shaped bottle created by magnetic fields, described as magnetic confinement.