Fusion is a process by which two or more atomic nuclei join together to form one or more heavier nuclei. The fusion of lighter nuclei releases energy, while the fusion of heavier nuclei consumes it. Fusion reactions are responsible for the energy production in stars, and occur under extreme conditions on Earth only in thermonuclear weapons and in experimental reactors.
The possibility of using fusion to produce energy has been investigated since the 1920s. In 1931, British astrophysicist Arthur Eddington proposed that the Sun’s energy comes from nuclear fusion reactions of hydrogen atoms. Nuclear fusion research was conducted throughout the remainder of the 20th century in both controlled laboratory settings and uncontrolled natural settings such as solar flares and magnetic reconnection events.
The first artificial self-sustained nuclear fusion reaction was achieved on November 3, 1953, using magnetic confinement at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) in California. This was followed by many other experiments leading to today’s Tokamak devices being able to confine plasma long enough for significant rates of nuclear fusion reactions to occur.
Currently, there are many initiatives underway worldwide to develop commercial nuclear fusion power plants based on Tokamaks or other designs. These projects are motivated by concerns about greenhouse gas emissions from fossil fuel electric power generation, security of supply of fossil fuels, and peak oil.
If successful, nuclear fusion power plants would offer a safe (no risk of meltdown), environmentally friendly (no carbon dioxide emissions), and virtually limitless source of energy with minimal waste products (helium and water). However, significant technical challenges remain before this goal can be realized, including developing materials that can withstand the extreme temperatures and pressures involved in a working reactor; designing a system that will efficiently extract usable energy from the reaction; and dealing with radioactive byproducts produced during operation