高温超伝導コイルで発生する常伝導領域の非接触型検出法

―低温容器外周のピックアップコイル群を使う新しい測定法の提案―

抄録

This study proposes a new indirect method of detecting normal transitions appearing in superconducting coil windings. In this method, multiple sets of pick-up coil pairs arranged outside the cryostat are used in order to electrically measure the occurrence of normal transitions during coil operation. This indirect method has benefits such as high reliability, safety and easy maintenance. The validity of this method was clarified theoretically and experimentally. In this experiment, tests of whether or not normal transitions could be detected were carried out on a Bi-2223 coil immersed in liquid nitrogen. The coil was closely wound into a single-layered, solenoidal coil shape with Ag-sheathed multifilamentary Bi-2223 tapes. The results showed that signs of normal transitions were successfully detected using this method when the winding area of the coil was warmed up locally using nitrogen gas.