Nuclear Fusion

Nuclear fusion occurs when  two or more light and small nuclei come together to perform a heavier nucleus.
This process is accompanied by the release of a huge amount of energy.

For example

Deuterium + Tritium = Helium + neutron + (Energy)
(2H1) + (3H1) = (4He2) + (1n0) + Energy



It is far more difficult to achieve fusion than fission due to the nature of the hydrogen nuclei that repel each other. In order to let this happen, the nuclei should be heated up to 10^8 K or more so that the nuclei will have enough kinetic energy to overcome the electrical repulsion between the nuclei.

The Sun acquires its energy from the fusion of hydrogen nuclei.

- Deuterium clashes with tritium to form a helium nucleus at a high temperature. This is accompanied by the release of a neutron and mass defect. The mass defect produces a massive amount of energy.

A hydrogen bomb also uses the principle of nuclear fusion for its design.