Current limits to wire technology

摘要

Soon after their discovery over a decade ago, high-temperature superconductors (HTS) promised applications in the power industry, where superconducting wires could carry large electric currents with virtually no energy loss. Unfortunately, the materials are extremely complex, and their properties present several serious obstacles to the development of wires. Today, many of these problems have been ingeniously solved, and 1-km lengths of BiSrCaCuO superconductors (BSCCO) are routinely produced by companies in the United States and Japan. These wires, which are actually multi-filament composite silver/superconductor ribbons, have already shown their practical uses in a number of prototype devices, including motors, transformers, fault-current limiters, and power transmission cables. But their performance is far below optimum, with less than 10% of the superconductor effectively carrying current. Understanding the sources of this problem is essential to the viability of the technology. On page 906 of this issue, Cai and colleagues describe experiments on single filaments extracted from a BSCCO tape, which shed new light on the barriers to current flow.