The general idea
(Nuclear Physics 101)
Nuclear fission requires large nuclei, from atoms such as uranium, which are then split into two smaller nuclei of roughly equal size. When this occurs, energy is released. A few neutrons are also released. These neutrons can then bombard other nuclei, which split and release neutrons. This is known as a chain reaction. An uncontrolled chain reaction causes an explosion. This phenomenon is used in the atomic bomb. Controlling this reaction produces useful energy. This is how nuclear power plants operate. Fission, however, creates radioactive nuclear waste.
Nuclear fusion, on the other hand, requires small nuclei, such as hydrogen, which are then combined to create a larger nucleus. This fusing of nuclei releases energy and neutrons. Just as in a fission reaction, these neutrons can be used to help continue the reactions.
In order to overcome the repelling force between the two positively charged nuclei, these nuclei must have a great amount of kinetic energy. There are several ways of raising their kinetic energy to the point needed for fusion. One is to accelerate one of the nuclei to very high speeds in an accelerator. Another way is to raise the energy of both nuclei by using very high temperatures. Neutrons released in deuterium-tritium fusion reactions can also help to increase the energy of the nuclei.
Using high temperatures to increase this energy is called "thermonuclear fusion," or "hot fusion." This type of fusion is used in the hydrogen bomb, and in the Sun and other stars.
If the fusion reaction takes place at normal room temperatures, using an electric current or something besides high speeds or temperatures to cause the nuclei to fuse, it is called "cold fusion."
Does it exist?
Igloo of Cold Fusion
Why Cold Fusion?
A Dictionary of Nuclear Terms
Cold Fusion Links