DEVELOPMENTS OF HIGH-T-C SUPERCONDUCTING CURRENT FEEDERS FOR A LARGE-SCALE SUPERCONDUCTING COIL SYSTEM

A large-scale superconducting coil system, which is an essential techn ology for a fusion reactor, requires large capacity and high performan ce current feeders from the power supplies at the room temperature to the superconducting coils at the operating temperature, which is usual ly liquid helium temperature at present. The superconducting current f eeders are being considered as a promising application of a high tempe rature superconductor (HTS), which can satisfy the requirements of a l arge current capacity and a low heat in-leak, simultaneously. To study the feasibility of the HTS current feeders, a melt-textured YBCO bulk superconductor was selected as a candidate material because of its hi gh current transport characteristics. The YBCO disk fabricated by quen ch and melt growth process was cut into a short sample with the cross section of 7 mm x 7 mm and the length of 40 mm and was mounted on the copper bars to perform the actual large current transport tests. The s ample could be successfully excited up to 20 kA at 4.2 K and 10 kA at 77 K. These performance test results and the Further R&D items for the HTS current feeders are discussed. (C) 1998 Elsevier Science B.V. All rights reserved.