Manufacture and Thermal Stability of Small HTS Magnet With a Joint

HTS sample magnet having two double pancake sub- coils was manufactured. In HTS magnet coil, lab joint method has been conventionally, used. Such joint has some disadvantage: while handling, easy damage on HTS tapes occurs. On the contrary, parallel joint method has merits: easy handling to solder, less damage. Accordingly, such method was adopted to connect between two sub-coils. At 77.3 K, resistance of parallel joint with 20 cm in length was 55 nOmega up to about current 130 A. At 21.0 K, resistance of parallel joint was 31 nOmega and critical current (I_c) of HTS magnet higher than 500 A. In simple calculation, Joule heat was calculated 7.8 mW in the joint region under operating current 500 A, and Joule heat in HTS magnet was 565 mW. From such consideration of Joule heat generation, this joining method is available for fabricating HTS magnet.