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| Nuclear Fusion |
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| The sun is the most enormous and direct,
source of energy. Where does this enormous energy that the sun radiates come
from? The source of this energy was not known to mankind until the year
1939. It was a German physicist, Hans Bethe, who proposed that the sun
contains hydrogen nuclei in its core, moving at large speeds. Whenever these
nuclei fuse to form a nucleus of a heavier element, a large amount of energy
is liberated. Such a reaction is known a nuclear fusion reaction. |
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| Fusion Reaction between Isotopes of Hydrogen |
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| Nuclear fusion is a reaction in which two or more light nuclei combine to form a heavy nucleus with the liberation of large amount of energy. |
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| Example: |
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| Nuclear fusion takes place at a very high temperature which is equal to 4 x 106 oC. Fusion is the combination of two like light nuclei and the nuclei must have sufficiently high kinetic energy to overcome the force of repulsion between the like nuclei. Therefore, for fusion reactions to occur, the two hydrogen nuclei have to collide at very high speeds, which is possible only at a very high temperature, equal to 4 x 106 oC. Hence a fusion reaction is also known as thermonuclear reaction. |
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| Fusion releases more energy than fission because the mass lost during fusion is more than that lost during fission. |
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| One of the practical application of nuclear fusion is hydrogen bomb. |
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| Hydrogen Bomb |
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| The basic principle involved in the
preparation of hydrogen bomb is nuclear fusion. A nuclear fission reaction
initiates the fusion reaction. In a hydrogen bomb the set up for fission
reaction is surrounded by a mixture of deuterium (21H)
and lithium. The nuclear fission reaction liberates heat energy and
neutrons. The heat energy released creates a temperature equal to 4 x 106
oC and the neutrons are used for converting 63Li
to tritium. The reactions taking place in a hydrogen bomb is as follows: |
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