Heat treatment study of Nb3Sn strands for the Fermilab'shigh field dipole model

摘要

Fermilab is developing high field superconducting dipole magnets based on Nb3Sn for a post-LHC very large hadron collider (VLHC). The first prototype is a 1 meter long two-layer shell-type (cos-theta) coil with a nominal field of 11 T. A keystoned Rutherford-type cable made of 28 Nb3Sn strands of 1 mm in diameter is used. The development of high Jc multifilamentary Nb3Sn strands with low magnetization is an important step of this program. To achieve this goal, strand R&D is actively pursued by Fermilab and IGC using the internal tin process. Conductor designs, heat treatment studies, and results of measurements, including Ic , n-value, RRR, magnetization, and chemical analyses, are presented