Title :
Development of high performance Nb-Ti(Fe) multifilamentary superconductor for the LHC insertion quadrupoles
Author :
Lee, P.J. ; Fischer, C.M. ; Gabr-Rayan, W. ; Larbalestier, D.C. ; Naus, M.T. ; Squitieri, A.A. ; Starch, W.L. ; Barzi, E.Z.A. ; Limon, P.J. ; Sabbi, G. ; Zlobin, A. ; Kanithi, H. ; Hong, S. ; McKinnell, J.C. ; Neff, D.
Author_Institution :
Appl. Supercond. Center, Wisconsin Univ., Madison, WI, USA
fDate :
6/1/1999 12:00:00 AM
Abstract :
A development program was initiated in order to develop strand with improved current density at 10.5 T and 1.9 K over existing SSCL designs. The two successful strand designs reported on here both utilized high Fe content Nb-47 wt%Ti alloys to improve the critical current density at high field by 7 %. At 10.5 T and 1.9 K, critical current densities exceeding 1450 A/mm/sup 2/ were obtained. In this paper we report detailed quantification of the macro- and micro-structures of these strands and correlate these with critical current density measurements at 1.9 K and 4.2 K. The high Fe content significantly reduced the /spl alpha/-Ti precipitate size. The linear relationship between critical current density and precipitate volume found is in agreement with earlier studies. High resolution FESEM electron backscatter contrast suggests a thin layer of high atomic number at grain boundaries.
Keywords :
accelerator magnets; alloying additions; critical current density (superconductivity); field emission electron microscopy; iron alloys; multifilamentary superconductors; niobium alloys; precipitation; scanning electron microscopy; superconducting magnets; titanium alloys; type II superconductors; /spl alpha/-Ti precipitate size; 1.9 K; 10.5 T; FESEM electron backscatter contrast; Fe content; LHC insertion quadrupoles; Nb-Ti-Fe; critical current density; current density; grain boundaries; high performance Nb-Ti(Fe) multifilamentary superconductor; macro-structures; micro-structures; precipitate volume; strand designs; Atomic layer deposition; Atomic measurements; Backscatter; Critical current density; Current density; Current measurement; Density measurement; Electrons; Iron alloys; Size measurement;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
