The Superconducting Revolution

Phase 5

Equipment development and the future.

Fujikura's challenge to lead the world with more original and innovative technology than anywhere else has begun.

Y-based superconducting wires have high critical current characteristics in magnetic fields, so they can be used for a variety of applications. They are particularly suitable for devices that use magnetic fields (such as linear motor cars, diagnostic MRIs, and energy storage devices). These devices use magnets made of coiled superconducting wires. When processed into a coil, bending and tensile strain occurs during winding. Electromagnetic forces also act when electricity is passed through the wire. Furthermore, there are various issues that cannot be understood at the wire level for device applications, such as the balance with cooling and what phenomena will occur under abnormal conditions. Therefore, there are many things that need to be considered prior to device application, and these issues need to be fed back into the wire manufacturing process.

Fujikura therefore repeatedly carried out various hypotheses and verifications, including investigating the superconducting properties when the superconducting wire is bent, investigating the operating characteristics of magnets made from coiled superconducting wire, conducting experiments in which electricity was passed through the wire beyond the critical current, and checking temperature changes in liquid nitrogen.

In fact, when electricity was passed through it, nothing happened. Furthermore, when electricity was passed through it beyond the critical current, a slight transition to normal conductivity occurred, and a voltage was observed. When the current was further increased, the voltage rose, but the thermometer attached to the magnet did not move at all. This means that when Y-based superconducting wire is application in equipment, it can operate more stably than conventional metallic superconducting equipment.

Furthermore, in 2006, in order to understand the magnet's excitation characteristics at temperatures lower than 70K, the temperature of liquid nitrogen, a refrigerator-cooled magnet was produced. Using this magnet, the excitation characteristics were investigated at temperatures between 30K and 70K. The results showed that stable current flow was possible, just as in liquid nitrogen.

Based on these results, the first motor using Y-type superconducting wire was manufactured. The motor was rated at 360 rpm and 15 kW and was intended for use on ships, with superconducting wire used in the magnetizing coil. The armature was a semi-superconducting motor that used copper wire. After completing the motor rotation tests, an actual screw was attached and tests were carried out underwater to test its characteristics for use on ships. The results were excellent, and the momentum towards practical use was finally building.

As mentioned above, Y-based superconducting wires have reached a level where they can be manufactured in lengths of over 500m. Furthermore, the critical current has also reached a level where it can exceed 500A at liquid nitrogen temperatures. In the future, they will continue to improve the characteristics and hone the technology to manufacture long lengths at low cost, while verifying application of this technology to various superconducting devices. They will continue their approach to provide the technology to the world as soon as possible. The crucial moment will come if they are to succeed as a business. Fujikura's challenge to lead the world with more original and innovative technology than anywhere else has begun...

Many of the research results mentioned above are the results of the research and development projects "Development of Superconducting Power Application Technology" (1987-1998), "Research and Development of Basic Technology for Superconductivity Applications (Phase I)" (1999-2002), and "Research and Development of Basic Technology for Superconductivity Applications (Phase II)" (2003-2007), which were commissioned by the New Energy and Industrial Technology Development Organization (NEDO).