CPEP Fusion Overview
The fusion process powers the sun and other stars. In a fusion reaction, light nuclei combine, or fuse, to form heavier nuclei. Through fusion reactions, mass energy is converted to kinetic energy as described by Einstein's formula, E = mc^2. In the sun, a sequence of fusion reactions named the p-p chain begins with protons, the nuclei of ordinary hydrogen, and ends with alpha particles, the nuclei of helium atoms. The p-p chain provides most of the sun's energy, and it will continue to do so for billions of years.
To make fusion happen on the earth, atoms must be heated to very high temperatures, typically above 10 million K. In this high-temperature state, the atoms are ionized, forming a plasma. This plasma must then be held together (confined) long enough that many fusion reactions occur. If fusion power plants become practical, they would provide a virtually inexhaustible energy supply because of the abundance of fuels like deuterium. Substantial progress towards this goal has been made, but many challenges remain.
This site supplies the essential scientific information about this fundamental energy source. The site is organized in layers. To dig deeper into the fundamental physics of fusion, simply explore any of the Guided Tour topics in the menu frame at left. For visitors new to the subject of fusion, we recommend proceeding in the listed sequence. Learning about fusion is an intellectual odyssey for all of us, even the scientists on the cutting edge of fusion research! The development and exploitation of fusion energy remains one of the grand challenges of science. But we hope we've made it easier for you to learn about it than for scientists to develop it! Please let us know if we can improve the site in any way.
CPEP grants permission for teachers and students to reproduce these copyrighted images and materials for their personal or classroom use, provided http://FusEdWeb.llnl.gov/CPEP/ is cited as the source. For other CPEP copyright permissions, email firstname.lastname@example.org.