Speaker
Description
In this paper we will report the recent progress of making ternary APC (Artificial Pinning Center) Nb3Sn conductor using internal oxidation technique in Hyper Tech. Our ternary APC Nb3Sn conductors with Ta and either Zr or Hf 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 ternary APC conductors have surpassed the best state-of-the-art Nb3Sn and the Jc,non-Cu specification of the Future Circular Collider (FCC). Their Bc2 was about 28 T, about 1-2 T higher than present state-of-the-art conductors. This APC strand has been made to 217-filament restack strands getting filament size of 35 micros at the 0.7 mm strand. These newly developed APC wires have RRR above 150 while surpassing the Jc,non-Cu specification of the FCC.
We will also report the progress in increasing the specific heat (Cp) of the Nb3Sn conductors to increase the energy margin against quenching by adding certain high Cp material in the strands. We successfully made 217-filament restack strands with filament size of 35 micros at the 0.7 mm strand and demonstrated the higher specific heat strands has much higher Minimum Quench Energy (MQE) values while keeping its high Jc and high RRR.
