ITER用内锡法Nb3Sn超导线材的不可逆温度研究

本文采用超导量子干涉仪(SQUID)测定了一种国际热核聚变实验堆(ITER)项目用内锡法Nb3Sn超导线材的不可逆温度,测量方法是在恒定磁场下循环温度,即将温度以一定间隔从10K上升到20K,然后再返回到10K,测定磁矩的偏离温度.所得结果可用于从生成最佳Nb-Sn相组成方面来优化A15相成相热处理制度.本研究得出的结论是,对于像ITER使用的高场磁体超导线来说,鉴于其需要在较高磁场下有高的临界电流密度,就需要将超导线的热处理温度适当提高一些.本实验所用Nb3Sn超导线材的最适宜热处理制度为675°C/128小时,这样可以得到最佳不可逆温度特性,即最佳的A15相组成.

IRREVERSIBILITY TEMPERATURE INVESTIGATION OF ITER Nb3Sn WIRE BY INTERNAL-Sn PROCESS

The irreversibility temperature of ITER Nb3Sn superconducting wire which is made by internal-Sn process was measured with a SQUID magnetometer by cycling the temperature from 10K to 20K and then down back to 10K at a constant magnetic field. The obtained results could be used to optimize the A15 phase formation heat treatment process and to determine the superior Nb-Sn phase composition of the reacted wire. Our study demonstrates the conclusion that with the requirement of high Jc at higher field for the wire of ITER's high-field magnets, it is necessary to heat-treat the wire at a relatively higher temperature for a suitable time. For ITER's wire, a little higher enduring temperature of 675℃ for around 128hrs dwelling time should be the suitable selection owing to the best irreversibility property and thus the super A15 phase composition.