29.1 Fission and Fusion

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At the beginning of this module, molecules, atoms, protons, and particles were characterized as different sized balls.  

In the Sun, two very small balls collide to produce a slightly larger ball and release a huge amount of energy.  Specifically, multiple hydrogen nuclei join together (fusion) to form a heavier helium nucleus, accompanied by the release of massive amounts of energy.  If humans could effectively replicate this on Earth, we would have an ideal source of power. On a small scale, fusion can be sustained in a reactor such as the one in the photograph.  Such a reactor would combine multiple hydrogen nuclei to form helium, which is environmentally clean and biologically harmless.

Fusion reactions involving hydrogen, however, need to have sustained temperatures ranging from 45 - 400 million degrees Kelvin.  In the Tokamak reactor vessel, plasma is heated in a doughnut-shaped vessel called a torus.  Magnetic fields are used to contain the superheated plasma, preventing it from contacting the vessel walls.

Although very promising in theory, current fusion technology can only sustain the reaction for a few seconds while producing only slightly more energy than it consumes.  Significant technological advances need to be made before fusion becomes a practical energy source, one that is clean, safe, and abundant.

Plasma: ionized gas in which the electrons have been separated from the nucleus

Split image showing the interior of a nuclear fusion reactor and the superheated plasma when it is in operation.