Nuclear fusion

In physics, nuclear fusion is the process by which two nuclei join together to form a heavier nucleus. It is accompanied by the release or absorbtion of energy depending on the masses of the nuclei involved. The iron nucleus has the largest binding energy of all nuclei and so is the most stable. The fusion of two nuclei to produce a nucleus lighter than iron generally gives off energy while the fusion of nuclei heavier than iron absorbs energy. Nuclear fusion of light elements is the energy source which causes stars to shine and hydrogen bombs to explode. Nuclear fusion of heavy elements occurs in the extreme conditions of a supernova explosion. Nuclear fusion in stars and supernovae is the primary process by which new natural elements are created.

Related Topics:
Physics - Nuclei - Energy - Binding energy - Star - Hydrogen bomb - Supernova

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

This article deals with the fusion reaction itself. For information on controlling the fusion reaction to produce useful power, see the article on fusion power.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

It takes considerable energy to force nuclei to fuse, even those of the least massive element, hydrogen. But the fusion of lighter nuclei, which creates a heavier nucleus and a free neutron, will generally release even more energy than it took to force them together — an exothermic process that can produce self-sustaining reactions.

Related Topics:
Hydrogen - Free neutron - Exothermic process

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The energy released in most nuclear reactions is much larger than that for chemical reactions, because the binding energy that glues a nucleus together is far greater than the energy that holds electrons to a nucleus. For example, the ionization energy gained by adding an electron to hydrogen is 13.6 electron volts -- less than one-millionth of the 17 MeV released in the D-T (deuterium-tritium) reaction shown to the right.

Related Topics:
Energy - Nuclear reactions - Chemical reactions - Binding energy - Electrons - Ionization energy - 13.6 - Electron volts - 17 MeV

~ ~ ~ ~ ~ ~ ~ ~ ~ ~