Speaker
Description
Internal oxidation technique could generate nano oxide particles in Nb3Sn strands, which could significantly refine the Nb3Sn grain size and boost the high-field critical current density. Our recent APC (Artificial Pinning Center) Nb3Sn wires with Ta and Zr doping demonstrated substantial grain refinement and significantly increased Jc,nonCu, while retaining the high Bc2 values of the best ternary Nb3Sn conductors. The non-Cu Jcs of these APC conductors has reached nearly 1500 A/mm2 at 16 T/4.2 K, which achieve the current CERN FCC target. Their layer Jc reaches 4700 A/mm2 at 16 T/4.2 K - more than double the present best ternary Nb3Sn conductors. Their Bc2 was about 28 T, about 1-2 T higher than present state-of-the-art conductors. Microscopy analysis shows that this APC wires still have overly high residual Nb fractions due to the low Sn/Nb ratio, indicating that there is still great potential for further Jc,non-Cu improvement. This strand has been made to 61-filament restack strands getting filament size of 45 micros at the 0.5 mm strand.
