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History of Development

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History of Research on Superconductivity in SEI

 In the beginning of 1960's, SEI's research in superconductivity started from the research on metal superconductors wire materials that will become superconductive in liquid helium. Although various high-temperature superconductive materials were discovered, today, bismuth and rare-earth superconductors are seen as the candidates to practicalization. Since discovery of these superconductors, SEI has been striving toward the development of applied products and fabrication of wires from bismuth and rare-earth superconductors.

Bismuth Superconductors

 High-temperature superconductor composed of Bi (bismuth), Sr (strontium), Ca (calcium), Cu (copper), and O (oxygen) is called the bismuth high-temperature superconductor. The 2223 phase, which composition ratio of Bi, Sr, Ca and Cu is 2:2:2:3, has high critical temperature (110 K) and therefore was winning much attention as practicable material since its discovery. Recent improvement in performance of bismuth (2223 phase) high-temperature superconductor has realized the larger-sized prototypes, thus allowing prototyping of cables and magnets of actual sizes.

Rare-Earth Superconductors

 High-temperature superconductor composed of Re (rare earth), Ba (barium), Cu (copper) and O (oxygen) is called the rare-earth high-temperature superconductor. Rare earth includes Y (yttrium), Nd (neodymium), Sm (samarium), and Ho (holmium). The rare-earth high-temperature superconductors can synthesize the superconductors that are close to the monochrystals, and they have superior characteristics in critical current densities and in high magnetic fields.

Rare-Earth Superconductors

Application of Bismuth Superconducting Wires

100 m Cable Practicality Test

 When superconducting cables are to be used as the underground cables in urban areas, it will be possible to send large electrical power through the cables that are more compact than conventionally used ones. Because superconducting cables have small energy loss during transmission, energy conservation is expected. As the first step toward practical use, the long-term test of 100-thousand kw class superconducting cable (100 m) was successfully completed in July, 2001. This was the world's first test to be conducted on three superconducting cables implemented inside a trunk as one.

 
Switching-on of the long-term test

Switching-on of the long-term test
From left: Noritaka Kurauchi (the chairman of the board of SEI), Takeshi Taneichi (the vice president of Tokyo Electric Power Company), and Kaoru Samejima (the executive Vice President of Central Research Institute of Electric Power Industry).
(Titles are as of the time of this photo.)

The 100-m superconducting cable system jointly implemented by SEI, Tokyo Electric Power Company, and Central Research Institute of Electric Power Industry.

The 100-m superconducting cable system jointly implemented by SEI, Tokyo Electric Power Company, and Central Research Institute of Electric Power Industry. On the premise of Yokohama Research Laboratory, Central Research Institute of Electric Power Industry

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