High field insert coils from Bi-2212/Ag round wires

Bi-2212/Ag round wire is a promising and practical material for extending high field superconducting magnets beyond the limits of Nb-3 Sn. Efforts to develop superconducting magnets in the 25 to 30 T range include fabrication and test of practical size insert coils using this wire. Recent studies have focused on improvements in wire performance, wire insulation, and coil fabrication for wind-and-react coils. Continued improvements in the engineering critical current density (J(E)) and the critical current density (J(c)) performance have been achieved by optimizing the starting precursor composition, and the heat treatments. The highest J(E) of 1580 A/mm(2) at 4.2 K, 0 T and 420 A/mm(2) at 4.2 K, 31 T were obtained in 0.81 mm wire. In particular, significant progress on braided insulation has been made for enabling a robust procedure for wind-and-react Bi-2212 solenoid coils. Performance of three of these coils has been measured in background fields up to 19 T, showing good prospects for high field magnet application of this conductor.