Physics – 5.1.2 The nucleus | e-Consult

Nuclear fusion is the process in which two or more light nuclei combine to form a heavier nucleus. This process requires extremely high temperatures and pressures to overcome the electrostatic repulsion between the positively charged nuclei. A common example is the fusion of deuterium and tritium:

• ²H + ³H → ⁴He + ¹n

In this equation, a deuterium nucleus (²H) fuses with a tritium nucleus (³H) to form a helium nucleus (⁴He) and a neutron (¹n). The mass of the resulting helium nucleus and neutron is slightly less than the combined mass of the deuterium and tritium nuclei. This mass difference is converted into a tremendous amount of energy, again following the principle of E=mc². The energy released is even greater than that released in fission for a given amount of mass. This is because the strong nuclear force is attractive between nucleons, and the resulting nucleus has a greater binding energy per nucleon than the original nuclei. Fusion reactions are the primary source of energy in stars.