Feasibility Study for 15-Tesla Magnet using Rapid-Heating Quenching and Transformation Nb3Al Strand

Abstract

A new practically long copper stabilized Rapid-Heating Quenching and Transformation (RHQT) Nb3Al strand is presented, which is being developed and manufactured at the National Institute of Material Science (NIMS) in Japan. It has achieved a non-copper Jc of 1000 A/mm2 at 15 T at 4.2K, with a copper over non-copper ratio of 1.04, and a filament size about 50 µm. Using this strand the feasibility study of a 15 T dipole magnet is presented. For this study a Rutherford cable with 28 Nb3Al strands of 1 mm diameter will be fabricated early in 2006. A block-type magnet is designed using ROXIE, and the stress and strain in the coil is estimated and studied with the characteristics of the Nb3Al strand. The advantages and disadvantages of the Nb3Al cable are compared with the prevailing Nb3Sn cable from the point of view of stress-strain, and possible effects on Jc due to cabling is presented. The Nb3Al coil of the magnet, which will be made by wind and react method, has to be heat treated at 800 degree C for 10 hours. As preparation for the 15 T magnet design, a series of tests on strands and Rutherford cables is presented.