Abstract
A prototype of 250 A-class Y-Ba-Cu-O bulk current leads usable in magnetic fields has been fabricated and studied for transport, mechanical and thermal properties. In this current lead, a melt-processed bulk superconductor 5mm wide and 0.8mm thick was reinforced by a support made of glass fiber-reinforced plastic (GFRP). The current leads could carry 300 A in liquid nitrogen for 10min without a rise in voltage, although the bulk superconductor was under thermal stress due to the difference in thermal expansion between the bulk superconductor and GFRP. In the bending test, the bulk superconductor was not broken although the copper electrode was plastically deformed. Thermal input of the current lead was estimated to be 0.12W under the condition that the high-end temperature was 77.3K and the low-end temperature was 4.2K. Furthermore, using the numerical method, it was possible to visualize distribution of the temperature and the heat flux inside the current lead.
