抄録
Superconducting current leads have been prepared by the TFA-MOD processed YBCO tapes. YBCO tape is 5 mm in width, and about 120 µm in thickness. The YBCO superconducting layer, 1.5 µm in thickness, is formed on oxide buffer layers of GZO and CeO2 deposited on HastelloyTM substrate tapes. Transport current is supplied through Ag layer deposited on YBCO layers. Current leads No.1 and No.2 have been composed of 20 YBCO tapes soldered to Cu caps at both ends. The two stainless steel boards as the shunt have been attached to current lead at both sides. The YBCO tapes with critical current of about 80 A (current lead No.1) and 61 A (current lead No.2) at 77 K in self-field have been used for current lead No.1 and No.2, respectively. The transport current of 1,600 A in current lead No.1 and 1,200 A in current lead No.2 were stably carried in liquid nitrogen without any voltage appearance on each tapes. The heat leakage of current leads No.1 and No.2 composed of 20 YBCO tapes, two stainless steel boards and GFRP board between 77 K and 4.2 K is calculated to be 547 mW (342 mW/kA : current lead No.1), 535 mW (446 mW/kA : current lead No.2), which is much smaller than that of conventional Cu current lead (1.2 W/kA). The small heat leakage results from high current performance and low thermal conductivity in the present superconducting current leads.
