A Scalable APC Approach to Increase Layer and non-Cu Critical Current in High Field in Nb3Sn Conductors
During this Phase I and Phase II, we succeeded in making Nb3Sn APC subelements and restacks with refined grain size in the reacted A15, and made the Nb3Sn APC subelements into 61-subelement restack strands and drew them down to 0.25 mm with subelement size of 25μm respectively. This is a big achievement. We obtained both magnetic and transport Jc at 10,000 A/mm2 at 12T-4.2K in the binary and Ti doped ternary APC Nb3Sn subelements, which is the basis for restack wires. We have modified the present design for a better Sn-SnO2/Nb ratio for increased phase formation, and have fabricated and are currently heat-treating a 61 subelement strand version of this conductor, which we believe will produce the 30-50 nm grain Nb3Sn and obtain high Je as well as Jc. Based on the work accomplished in this Phase II, we are further optimizing the chemistry and the powder mixing procedure in the current continuous Phase II project. Our recent APC-PIT Nb3Sn strands could be drawn down to 0.5 mm with filament size of 45 micros without breakage. Our recent APC Nb3Sn wires with Ta and Zr doping gave Birrs and Bc2s in the 26-28 T range, values that are at or above those of the current best ternary Nb3Sn conductors. The non-Cu Jcs of these APC conductors have reached nearly 1200 A/mm2 at 16 T/4.2 K, similar to present best ternary Nb3Sn conductors. Their Layer Jc reaches 4700 A/mm2 at 16 T/4.2 K which is more than doubled the present best ternary Nb3Sn conductors. These conductors’ fine grain fractions are still significantly below those of current standard Nb3Sn conductors due to the lack of recipe and heat treatment optimizations. Further chemistry and HT optimization will push the non-Cu Jc at 16T/4.2K to 2000-2400 A/mm2, which is greater than the target for CERN-FCC, 1500 A/mm2 at 16 T/4.2K.
- Research Organization:
- Hyper Tech Research Inc.
- Sponsoring Organization:
- USDOE
- Contributing Organization:
- Fermi Lab; Ohio State University
- DOE Contract Number:
- SC0013849
- OSTI ID:
- 1487382
- Type / Phase:
- SBIR (Phase II)
- Report Number(s):
- DE- SC0013849
- Country of Publication:
- United States
- Language:
- English
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