Fusion combines light nuclei — requires extreme temperatures to overcome repulsion

Nuclear Energy & Binding Energy — AQA A-Level Physics

Key Definition

Nuclear fusion — The combining of two small nuclei to produce a larger nucleus, releasing energy because the product has a higher binding energy per nucleon.

Occurs in light nuclei (A < 56) where the product is closer to the iron peak.
Example: deuterium + tritium → helium-4 + neutron + energyThe capacity to do work. Measured in joules (J).. This is the reaction powering stars.
Two barriers must be overcome: electrostatic repulsion between the positive nuclei, and the short range of the strong nuclear force.
Nuclei must have extremely high kinetic energyThe capacity to do work. Measured in joules (J).The energyThe capacity to do work. Measured in joules (J). an object possesses due to its motion. to get close enough — temperatures of tens of millions of kelvin.
Fusion releases more energy per kg of fuel than fission.