Yonghoon Kim, Takumi Sato, Hiroyuki Fukushima, Hideki Ii, Hirokazu Tsubouchi, Kiyoshige Hirose
Abstract
We have developed the self-bonding NbTi wires for superconducting magnets, which can eliminate an epoxy impregnation process which requires some time and cost in the superconducting coil manufacturing, and we have evaluated its bonding strength and the characteristics of the superconducting coil. Consequently, we confirmed the optimum heat treatment condition to obtain a sufficient bonding strength and found out that the properties are stable without degradation of the bonding strength after the heat cycle treatment between room temperature and ultralow temperature. As the current test result on a sample of small-sized superconducting coil made of self-bonding NbTi wires, we found that it had the characteristic equivalent of an epoxy impregnated coil with no characteristic degradations were caused by heat cycle or quench occurred and, in a 4.5 T backup magnetic field, a 100% load factor and an 8.0 T maximum experienced magnetic field could be achieved. A mediumsized superconducting coil had no characteristic degradations after heat cycle or quench and 100% load factor was achieved under the current test, therefore we could confirm the usefulness of the self-bonding superconducting wire.
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