* Completion of the world's largest superconducting coil ever built
* Director-
* Established technology and techniques for welding large cryogenic stainless steel structures (approx. 230mm in thickness), enabling enormous superconducting coils (16.5m high, 9m wide, gross weight 300t) to be manufactured having a level of precision within 0.01%
The newly completed TF coil is the first main structural component for ITER's magnet system, and its completion is a major milestone forward for the reactor's construction. Plans call for five TF coils to be produced at the Futami Plant, which will be shipped from
Project Background
ITER's superconducting TF coils are D-shaped and approximately 16.5m in height, 9m wide, and weigh some 300 tonnes. Eighteen TF coils will encompass the vacuum vessel container and generate a powerful magnetic field (maximum of 12 tesla) to confine high-temperature, high-density plasma within the vessel.
Significance of Latest Achievement
To confine plasma inside ITER, a highly precise, strong magnetic field (12 tesla) is required, which called for the development of unprecedentedly large superconducting coils that use niobium-tin conductors. To maintain superconductivity, the coils must be able to function in cryogenic temperatures of -269 -degreeC, which required special stainless steel structural materials capable of withstanding such low temperatures to be developed along with all requisite manufacturing technology. Not only was there no precedent for coils of this unsurpassed scale, the dimensional tolerances of the windings and coils required a high precision of within 0.01%.
QST commenced R&D for the TF coil manufacturing technology in 2005, and MHI began their manufacture in 2012. Working in collaboration, QST and MHI developed high-precision technology for winding niobium-tin conductors, and also developed durable structural materials made from a special stainless steel capable of withstanding cryogenic temperatures. Furthermore, to determine the conditions to suppress deformations caused by welding, parameter tests were conducted and the welds were verified using both miniature and full-scale specimens, which formed the basis for the fundamental technologies suited to the material's properties, including advanced welding procedures and machining techniques. In the end we were able to meet the stringent requirements demanded for ITER.
Future Schedule
Plans call for a total of five TF coils to be shipped from the Futami Plant in the run-up to the start of ITER operations in 2025. Completion of the first TF coil will give
Fusion is the energy source that enables the sun to keep shining. The ultimate goal is achieving fusion here on Earth. Fusion reactions fuse light atomic nuclei-deuterium and tritium-in a plasma environment into a heavier element, helium. Fusion reactions emit zero carbon dioxide, and their source of fuel can be extracted from seawater in virtually unlimited quantities (lithium from which tritium is derived, and deuterium). Fusion energy is expected to provide fundamental solutions to many of the world's energy and environmental problems.
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