Increasing the Jc of Tube-Type Nb3Sn Strands, Phase I Final Report.

摘要

In this Phase I, we successfully made strands with better Cu/Sn ratio to reduce the coarse Nb3Sn grain region, thereby providing the potential of increasing the non-Cu Jc in the Phase II and scaling up to 2 billets with 331 subelements. In order to improve the strands high field properties, we successfully doped low amount of Ti in the subelements and made a 217- subelement wire which has been drawn down to 0.7 mm without any breakage. This strand gave subelement size of 35 im. We will scale up the Ti-doped billet to 271-subelement in 1.5 billet in this proposed Phase II. The hexagonal shaped subelements with round Nb-Sn have been developed for a 61-subelement restack. Thus the results indicated that for 217-subelement restack in a 2 billet we have the potential to draw down this type of construction without problems while maintaining a good array to react more Nb to get higher non-Cu Jc in the Phase II.