The Superconducting Revolution

Phase 4

Towards further technological evolution.

Japan surpassed the United States by extending the cable length by 100m, and became the world leader in IcL value, the product of critical current and length.

In 2004, Fujikura was preparing to create the world's first 100m-long wire with a critical current of over 100A. That year also coincided with the biennial Applied Superconductivity Conference, an international conference on superconductivity that attracts many superconductivity researchers. As this conference attracts many researchers, the company planned to present the results of its 100m-long wire at the conference, and began preparations in July. To create a superconducting wire, it is necessary to deposit an intermediate layer, a superconducting layer, and a stabilizing layer, followed by heat treatment. The deposition equipment at the time was smaller and less powerful than today's, so it took more than two months to complete the entire process.

Just as they were completing the intermediate layer and about to deposit the superconducting layer, a critical component in the excimer laser they relied on broke down. They inquired with manufacturer representatives and other research institutions about the same component, but they couldn't find it anywhere. Just when it seemed all hopeless, they had an idea: they might be able to produce 100 meters of wire by using the excimer laser they had been using for basic experiments. However, this method would require not only moving the laser's position, but also reconnecting the laser's raw gas and cooling water pipes. Counting backward from the date of the conference presentation, they only had a few dozen hours to complete the work. Fujikura's engineering team immediately took measurements on the spot, and construction began the next morning. They prepared the paper for the conference presentation so that they only needed to include the performance figures at the end, and they were able to determine the superconducting wire's properties two days before the conference presentation, successfully completing the presentation.
At the time, a project had just begun in the United States with the goal of developing a 100m superconducting wire in four years. When they heard from Japan that their goal had been achieved, American researchers could hardly believe their ears. Truly unbelievable! It's not hard to imagine that this caused considerable jealousy and resentment.

Six months after developing the 100A, 100m superconducting wire, Fujikura started developing a 200A, 200m long wire. They faced many difficulties, but overcame them all. They achieved a 200m long wire in 2006. The NEDO project was to develop a 300A, 500m long wire by the end of 2007. Fujikura then set out to lengthen the superconducting layer as a challenge, and through trial and error. They worked on the first wire production in the summer of 2007, and as a result, they established the basic production technology for long wires. The continuous length was 368m, exceeding 300A, and the lowest critical current was 305A. Incidentally, the IcL value, which is the product of the critical current and length, was 112,000A. It took only four months, but they maintained their position as the world's best. After that, they continued to refine the manufacturing process of the superconducting layer to improve the superconducting properties, and after forming an intermediate layer, they finally completed a 500m superconducting wire. The critical current for the entire length was 350A over 504m. The IcL value at this time was 176,000A, once again taking the number one spot in the world.