On Earth, to recover fusion energy, scientists are concentrating on the most accessible reaction: the fusion of deuterium and tritium, two isotopes of hydrogen containing one proton and one or two neutrons respectively.
This reaction produces a helium nucleus, also known as an alpha particle (α), and a neutron with high kinetic energy.
- The α particles, charged particles, remain confined in the plasma and transmit their energy by colliding with the other particles. In this way, α particles contribute to the ‘self-heating’ of the plasma.
- The neutron, which has no electrical charge, is not confined: it is stopped in the wall of the installation. Its kinetic energy is transformed into heat. In a reactor, it will be recovered and transformed to provide electricity. The neutron is also used to regenerate tritium in situ, so that it cannot be handled outside the containment.