Development of a magneto-optical imaging equipment for long length 2G-HTS tapes

Abstract

We developed a characterization method suitable for high-Tc superconducting long tapes in prospect of practical use. In order to find low Jc regions with higher spatial resolution and to feedback to fabrication process of the next generation superconducting tapes of 123 system, we chose magneto-optical imaging (MOI) technique as one possibility. Previously, the maximum length that our MOI equipment can deal with was limited to 5cm by cryostat size. Therefore, we needed to develop new MOI equipment corresponding to high-Tc tapes of several hundred-meter lengths. It is the most important requirement of the new MOI equipment that the maximum length up to 500m in reel to reel can be measured. The other characteristic specifications of this apparatus are variable temperature (20–100K), 16mm square area observation at a time, and application of magnetic fields up to 100mT. By using this MOI equipment, we observed several kinds of 2G-HTS tapes produced by techniques such as IBAD(CeO2)/TFA-MOD(YBCO), IBAD(CeO2)/PLD(YBCO) on hastelloy tapes and confirmed the performance of the equipment.