Develop Nb3Sn Strands for Advanced Fusion Application with High Jc at High Field and Low AC Loss
- Hyper Tech Research Inc., Columbus, OH (United States)
During Phase I, we succeeded in making a 1 km billet of 0.82 mm diameter 919-subelement restack strands with filament size of 19 µm, which has non-Cu Jc of 2125 A/mm2 12T-4.2K which is more than doubled the current ITER project requirement (800 A/mm2) while having AC losses of about 500 mJ/cm3, which is lower than the current ITER project requirement (600 mJ/cm3). This strand was drawn down to the filament size of 16 µm, which has non-Cu Jc of 2078 A/mm2 which is more than doubled the current ITER project requirement (800 A/mm2) while having AC losses of about 400 mJ/cm3, which is much lower than the current ITER project requirement (600 mJ/cm3). Due to the time limit of the Phase I, we have not optimized the heat-treatment yet. In the following Phase II, we will optimize the current 919-subelement restack wire and potentially improve about 15% its non-Cu Jc while keeping the losses low. We will scale up and make larger billets to demonstrate piece lengths of 3-10km for this high count filament restack wire. We also succeeded in making subelements and restacks with refined grain size in the reacted A15, and made the subelements for 61-subelement restack strands and drew them down to 0.7 mm, 0.5 mm, 0.4 mm and 0.25 mm with filament sizes of 65 µm, 45µm, 35 µm and 25µm respectively, which is corresponding the 0.82 mm diameter of 61, 127, 271 and 547 subelement restack strands respectively. This is a big achievement. We obtained both magnetic and transport layer Jc at 10,000 A/mm2 at 12T-4.2K in the binary Nb3Sn with ZrO2 in the subelements, and have fabricated and heat-treated 61 subelement strands. This restack strands has refined grain size, but its non-Cu Jc is low since there is only partially reaction. As we move into the proposed Phase II program, we will first optimize the heat-treatment schedule of the restack wires in Phase I, and then further optimize the chemistry including Nb/Sn and Sn/Cu2O ratios in the subelement. We will make a 217-subelement restack strand of this optimized subelement and draw it down to 0.82 mm with subelement size of 40 µm and make a 547-subelement restack strands of this optimized subelement and draw it down to 0.82 mm with subelement size of 25 µm. Through this Phase II, we are focusing on making high count restack wire with refine grain size.
- Research Organization:
- Hyper Tech Research Inc., Columbus, OH (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- Contributing Organization:
- The Ohio State University
- DOE Contract Number:
- SC0017754
- OSTI ID:
- 1477164
- Type / Phase:
- SBIR (Phase I)
- Report Number(s):
- DE-SC0017754
- Resource Relation:
- Related Information: [1] X. Xu, M. Sumption, X. Peng, Applied Physics Letters, Vol. 104, No. 8, (2014
- Country of Publication:
- United States
- Language:
- English
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