Superconducting Magnets for the Hybrid Magnets at Tohoku University

Abstract

In the High Field Laboratory for Superconducting Materials at Tohoku University, we have built up in the last four years three hybrid magnets capable of 30 T, HM-1, HM-2, and HM-3. Two of these magnets, HM-3 (32 mm bore, 20 T) and HM-2 (52 mm bore, 23 T) have been already made available for the development of superconducting materials for nuclear fusion reactors. The outer, superconducting, parts SM-3 and SM-2 of these magnets, wound with multifilamentary NbTi conductors, can both generate 8 T and have the room temperature bores of 220 and 360 mm, respectively. The fabrication of HM-1, the maximum field of which had been designed to be either 31 T (32 mm bore) or 29 T (52 mm bore), was finished last spring and we succeeded in generating 30.7 T on May 29, 1985. A 12-T superconducting magnet (SM-1) with a room temperature bore of 360 mm was used in HM-1. SM-1 used Ti-doped Nb3Sn multifilamentary couductor. The design, construction, test and operation of these three superconducting magnets are reported in detail. A few examples of HC2 and Jc measurements in HM-1 are also presented.