Tuesday, August 24, 2010

Physics Form Five: Chapter 5 - Nuclear Fusion

Fusion is what happens when two atomic nuclei are forced together by high pressure and high temperature ... high enough to overcome the strong repulsive forces of the respective protons in the nuclei. When the nuclei fuse, they form a new element, and release excess energy in the form of a fast-moving neutron. The energy is 'extra' because the mass of the newly formed nucleus is less than the sum of the masses of the original two nuclei; the extra mass is converted to energy according to Einstein's equation E=mc2 . This energy can be used to do useful work!

Deuterium can be easily extracted from seawater, where 1 in 6500 hydrogen atoms is deuterium. Tritium can be bred from lithium, which is abundant in the earth's crust. In the fusion reaction a deuterium and tritium atom combine together, or fuse, to form an atom of helium and an energetic neutron.
Fusion is like lighting a match to a bucket of gasoline. You need that input energy (the match), but what you get as a result is far more powerful. Fusion fuel is very energy dense. A thimbleful of liquid heavy-hydrogen fuel could produce as much energy as 20 tons of coal. Or, more realistically, one pick-up truck full of deuterium would release the energy equivalent of approximately 2 million tons of coal (21,000 rail car loads), or 1.3 million tons of oil (10 million barrels), or 30 tons of Uranium Oxide (1 rail car load). Clearly, with seawater as our energy source, our energy problems would be over forever! 


Anonymous said...

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Anonymous said...

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