A tokamak is a device which uses a powerful magnetic field generated by external magnets to confine plasma in the shape of an axially-symmetrical torus. The tokamak is one of several types of magnetic confinement devices being developed to produce controlled thermonuclear fusion power. The tokamak concept is currently one of the leading candidates for a practical fusion reactor.
Fusion power is a proposed form of power generation that would generate electricity by using heat from nuclear fusion reactions. In a fusion process, two lighter atomic nuclei combine to form a heavier nucleus, while releasing energy. Devices designed to harness this energy are known as fusion reactors. Research into fusion reactors began in the 1940s, but as of 2024, no device has reached net power, although net positive reactions have been achieved.
This timeline of nuclear fusion is an incomplete chronological summary of significant events in the study and use of nuclear fusion.
ITER is an international nuclear fusion research and engineering megaproject aimed at creating energy through a fusion process similar to that of the Sun. It is being built next to the Cadarache facility in southern France. Upon completion of construction of the main reactor and first plasma, planned for 2033–2034, ITER will be the largest of more than 100 fusion reactors built since the 1950s, with six times the plasma volume of JT-60SA in Japan, the largest tokamak operating today.
Magnetic confinement fusion (MCF) is an approach to generate thermonuclear fusion power that uses magnetic fields to confine fusion fuel in the form of a plasma. Magnetic confinement is one of two major branches of controlled fusion research, along with inertial confinement fusion.
DEMO, or a demonstration power plant, refers to a proposed class of nuclear fusion experimental reactors that are intended to demonstrate the net production of electric power from nuclear fusion. Most of the ITER partners have plans for their own DEMO-class reactors. With the possible exception of the EU and Japan, there are no plans for international collaboration as there was with ITER.
The Experimental Advanced Superconducting Tokamak (EAST), internal designation HT-7U, is an experimental superconducting tokamak magnetic fusion energy reactor in Hefei, China. The Hefei Institutes of Physical Science is conducting the experiment for the Chinese Academy of Sciences. It has operated since 2006.
The National Spherical Torus Experiment (NSTX) is a magnetic fusion device based on the spherical tokamak concept. It was constructed by the Princeton Plasma Physics Laboratory (PPPL) in collaboration with the Oak Ridge National Laboratory, Columbia University, and the University of Washington at Seattle. It entered service in 1999. In 2012 it was shut down as part of an upgrade program and became NSTX-U, for Upgrade.
The Plasma Science and Fusion Center (PSFC) at the Massachusetts Institute of Technology (MIT) is a university research center for the study of plasmas, fusion science and technology.
The KSTAR is a magnetic fusion device at the Korea Institute of Fusion Energy in Daejeon, South Korea. It is intended to study aspects of magnetic fusion energy that will be pertinent to the ITER fusion project as part of that country's contribution to the ITER effort. The project was approved in 1995, but construction was delayed by the East Asian financial crisis, which weakened the South Korean economy considerably; however, the project's construction phase was completed on September 14, 2007. The first plasma was achieved in June 2008.
The beta of a plasma, symbolized by β, is the ratio of the plasma pressure (p = nkBT) to the magnetic pressure (pmag = B2/2μ0). The term is commonly used in studies of the Sun and Earth's magnetic field, and in the field of fusion power designs.
General Fusion is a Canadian company based in Richmond, British Columbia, which is developing a fusion power technology based on Magnetized Target Fusion (MTF). The company was founded in 2002 by Dr. Michel Laberge. The company has more than 150 employees.
A spherical tokamak is a type of fusion power device based on the tokamak principle. It is notable for its very narrow profile, or aspect ratio. A traditional tokamak has a toroidal confinement area that gives it an overall shape similar to a donut, complete with a large hole in the middle. The spherical tokamak reduces the size of the hole as much as possible, resulting in a plasma shape that is almost spherical, often compared to a cored apple. The spherical tokamak is sometimes referred to as a spherical torus and often shortened to ST.
The Culham Centre for Fusion Energy (CCFE) is the UK's national laboratory for fusion research. It is located at the Culham Science Centre, near Culham, Oxfordshire, and is the site of the Joint European Torus (JET), Mega Ampere Spherical Tokamak (MAST) and the now closed Small Tight Aspect Ratio Tokamak (START).
The Lockheed Martin Compact Fusion Reactor (CFR) was a fusion power project at Lockheed Martin’s Skunk Works. Its high-beta configuration, which implies that the ratio of plasma pressure to magnetic pressure is greater than or equal to 1, allows a compact design and expedited development. The project was active between 2010 and 2019, after that date there have been no updates and it appears the division has shut down.
The ARC fusion reactor is a design for a compact fusion reactor developed by the Massachusetts Institute of Technology (MIT) Plasma Science and Fusion Center (PSFC). ARC aims to achieve an engineering breakeven of three. The key technical innovation is to use high-temperature superconducting magnets in place of ITER's low-temperature superconducting magnets. The proposed device would be about half the diameter of the ITER reactor and cheaper to build.
Commonwealth Fusion Systems (CFS) is an American fusion power company founded in 2018 in Cambridge, Massachusetts after a spin-out from the Massachusetts Institute of Technology (MIT). Its stated goal is to build a small fusion power plant based on the ARC tokamak design. It has participated in the United States Department of Energy’s INFUSE public-private knowledge innovation scheme, with several national labs and universities.
SPARC is a tokamak under development by Commonwealth Fusion Systems (CFS) in collaboration with the Massachusetts Institute of Technology (MIT) Plasma Science and Fusion Center (PSFC). Funding has come from Eni, Breakthrough Energy Ventures, Khosla Ventures, Temasek, Equinor, Devonshire Investors, and others.
Spherical Tokamak for Energy Production (STEP) is a spherical tokamak fusion plant concept proposed by the United Kingdom Atomic Energy Authority (UKAEA) and funded by the UK government. The project is a proposed DEMO-class successor device to the ITER tokamak proof-of-concept of a fusion plant, the most advanced tokamak fusion reactor to date, which is scheduled to achieve a 'burning plasma' in 2035. STEP aims to produce net electricity from fusion on a timescale of 2040. Jacob Rees-Mogg, the UK Secretary of State for Business, Energy and Industrial Strategy, announced West Burton A power station in Nottinghamshire as its site on 3 October 2022 during the Conservative Party Conference. A coal-fired power station at the site ceased production a few days earlier. The reactor is planned to have a 100 MW electrical output and be tritium self-sufficient via fuel breeding.
The history of nuclear fusion began early in the 20th century as an inquiry into how stars powered themselves and expanded to incorporate a broad inquiry into the nature of matter and energy, as potential applications expanded to include warfare, energy production and rocket propulsion.
