What is fusion?

Fusion Energy is the tremendous energy source that powers the sun, stars and the universe. This energy is created by a nuclear fusion reaction burning hydrogen into helium. In this reaction, an extraordinary amount of energy is given off when the nuclei of light elements (hydrogen), fuse together to make heavier elements (helium). On Earth, the most practical method of producing a fusion reaction in the laboratory, is through the fusion of deuterium and tritium. Deuterium occurs naturally in molecules of heavy water (HDO). About 0.03% of the water in the oceans is heavy water, and Tritium can be easily produced from lithium in a nuclear reactor. The marvelous result of such a sustainable reaction here on earth, is the production of a clean, safe and almost limitless source of energy. The available supply of deuterium is sufficient to satisfy all our energy requirements for a billion years; the supply of lithium is sufficient for a million years. In order for a Deuterium-Deuterium (D-D) and Deuterium-Tritium (D-T) reaction to take place, a plasma temperature of about 5x10⁹K and 1x10⁸K are required respectively.

The Problem: To ignite a nuclear fire, the reactants must be heated to extremely high temperatures. But, if the nuclear fire is to yield enough energy, the reactants must be kept together for some minimum length of time. For example, a D-T plasma with a density of 10¹⁴cm^-3 must be confined for at least 2 seconds if it is to produce a sufficient amount of energy to reach the break even point. Thus, lies the great problem of plasma physics as plasma tends to escape and disperse. The challenge is to confine the plasma long enough to extract a significant amount of energy.

Fusion Education Links

Princeton Plasma Physics Laboratory Educational Website
General Atomics Educational Website
Plasma Science and Fusion Center's Educational Outreach Programs at MIT
MIT Alcator C-Mod
The Wonders of Physics - University of Wisconsin-Madison
Coalition for Plasma Science
Contemporary Physics Education Project (CPEP)
The American Physical Society Education and Outreach
Energy Information Administration
Slide Show of MIT's Mr. Magnet

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