Fusion glossary
D
The process by which the facility is permanently taken out of operation at the end of the plant lifecycle with adequate regard for the health and safety of workers and the public, and protection of the environment.
DEMO (DEMOnstration fusion reactor) is a generic term referring to the next class of experimental device to follow ITER, predecessor to a demonstration power plant. DEMO would generate electricity at the level of a few hundred MW and utilize all technologies necessary for a commercial device. See the After ITER page of the website for more information about the projects underway in the ITER Members.
An isotope of hydrogen. Its nucleus contains one neutron and one proton.
A plasma obtained by using deuterium and tritium as the fusion fuels. Also called a D-T plasma.
Reactions between the nuclei of two isotopes of hydrogen, deuterium and tritium, to release energy by nuclear fusion. Helium nuclei and neutrons are produced.
Equipment for determining/monitoring the properties and behaviour of a plasma during an experiment.
The DIII-D tokamak was developed in the 1980s by General Atomics in San Diego, USA, as part of the ongoing effort to achieve magnetically confined fusion. It is currently operated by General Atomics for the US Department of Energy. See this link.
A disruption is an instability that may develop within the tokamak plasma. Disruptions lead to the degradation or loss of the magnetic confinement of the plasma and, because of the high amount of energy contained within the plasma, the loss of confinement during a disruption can cause a significant thermal loading of in-vessel components together with high mechanical strains on the in-vessel components, the vacuum vessel and the magnet coils. Disruptions have been observed, avoided and mitigated in most operating tokamaks.
A system to protect machine components against excessive heat loads and electromagnetic forces resulting from plasma disruptions, in which there is a sudden loss of stored thermal and magnetic energy. See shattered pellet injection.
The component of the ITER device that removes helium "ash" and plasma heat during operation of the tokamak. Located at the very bottom of the vacuum vessel, the ITER divertor is made up of 54 remotely-removable cassettes, each holding three plasma-facing components, or targets. These are the inner and the outer vertical targets, and the dome.
The region of the divertor into which field lines in the plasma scrape-off layer are conducted.
Agencies created in each of the seven ITER Members to fulfil in-kind procurement responsibilities to ITER. In-kind procurement means that instead of supplying only cash to the ITER Organization for the construction phase of the project, Members are supplying 90% of their participation "in kind," in the form of systems, components and, in the case of Europe, buildings.
The building block of ITER's toroidal field and poloidal field superconducting magnets. Double pancakes are double layers of spiralled superconductor wound into the precise shape of the coil (D-shape for the toroidal field magnets, ring-shape for the poloidal field magnets). Six to nine double pancakes are stacked to form the final magnet assemblies.