Speaker
Description
The internal oxidation technique could generate oxide nano particles in Nb3Sn strands, which could significantly refine the Nb3Sn grain size and boost the high-field critical current density. Our recent Ta doped ternary APC Nb3Sn wires with ZrO2 pinning center 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 approaches the current CERN FCC spec. Their layer Jc reaches 4700 A/mm2 at 16 T/4.2 K - more than double the present best ternary Nb3Sn conductors. Even so, further improvements are possible using straightforward methods, and by using these we are pushing the fine grain fractions in these conductors up a further 10% to 20% which is expected to lead directly to proportionate increases their Jc. This strand has been made to 61-filament restack strands getting filament size of 45 micros at the 0.5 mm strand. In this paper, we will report the recent progress in this APC Nb3Sn wire.
This work was supported by the US Department of Energy, Office of High Energy Physics, Grants No. DE-SC0017755 and DE-SC0013849.
