The magnetic fields are produced by superconducting coils surrounding the vessel, and by an electrical current driven through the plasma.
A major step forward in fusion occurred in 1968 when the Russian scientists Tamm and Sakharov announced results from a new type of magnetic confinement device called a tokamak.
The toroidal, or doughnut-shaped, vacuum vessel was able to run at temperatures nearly ten times higher than any other device at the time.
Since its invention, many international experiments have relied on the tokamak concept.
American efforts on magnetic confinement fusion are being led by the Princeton Plasma Physics Laboratory (PPPL), based in Princeton, New Jersey. In January, 2012, PPPL announced an upgrade to their tokamak. The project will upgrade the National Spherical Torus Experiment (NSTX) facility at PPPL with completion scheduled for 2014. The work will enhance the position of the NSTX as the world’s most powerful tokamak.
The Joint European Torus (JET) project came into operation in 1983, about the same time as the Tokamak Fusion Test Reactor (TFTR) in the USA. It is hosted in the UK by the Culham Centre for Fusion Energy.
The Massachusetts Institute of Technology’s Alcator C-Mod tokamak pushes the bounds of knowledge on magnetic fields and plasma pressure, more than any other facility in the world. This research works to solve the key engineering challenges that remain before fusion energy can be commercialized. Photo: MIT, Plasma Science and Fusion Center.
General Atomics operates a fusion center on behalf of the Department of Energy outside of San Diego, called DIII-D. It is the third largest tokamak in the world, and focuses its research on plasma confinement and advanced tokamak designs.
Located in Troitsk, Russia, Ignitor is a tokomak collaboration between Russia and Italy, based on the approach taken by MIT’s Alcator C-Mod. Construction on the reactor is projected to be completed in 2014. Photo: RIA Novosti, Grigori Sisoev.
Located in Greifswald, Germany, the Wendelstein 7-X is a stellarator that will begin operation in 2014. A stellarator is different than a tokamak in that it could be better at producing a stable, confined plasma. Photo: IPP, Wolfgang Filser.
Located in Hefei, China, EAST was designated a “Mega Project of Scientific Research” in June 1997 by the Chinese government. Construction of the EAST tokamak was completed in 2006. It is the world’s first fully superconducting Tokamak. Photo: Chine Academy of Sciences, Institute of Plasma Physics.
Located in Daejon, South Korea, construction of KSTAR began in 1995, with the purpose of achieving steady-state operations with high-performing plasmas. It is one of the first tokamaks in the world to use fully superconducting magnets. Photo: Nature Publishing Group.
Located in Toki, Japan, the Large Helical Device (LHD) is a superconducting stellerator. It is the world’s largest helical fusion device. After the successful production of the first plasma in 1998, LHD’smission has been to increase the strength of the magnetic confinement field.
ITER will be the largest tokamak ever built. Conceived as a necessary experimental step on the road to a demonstration fusion power plant, the reactor will be twice the size of JET, the world’s largest tokamak currently in operation.