Coated conductors being used at the NHMFL are (not yet anyway) uniform

Data provided by Dmytro Abraimov (32 T testing), and further selected samples by Lidia Rossi, Xinbo

(Paul) Hu Jan Jaroszynski and Tak KametaniDavid Larbalestier

Data taken from D Abraimov(WAM-HTS Hamburg talk) and Lidia Rossi (MS thesis, University of Paris Marie Curie, June 2014 with stage at NHMFL Jan-Jun 2014)

Simple points

• Procurements have taken place over about 3 years

• SF 77K is not sufficient to specify conductor for any of our high field coils

• We have invested strongly in characterization capabilities

• Many variations are seen, more than those whose cause is understood!

0 20 40 60 80 100 120 1400

50

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450

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650

700

7501029

1038 1038

1038

1038

1022-11024-3

1028-1

1029-1

1030-1 1030-1

1030-1

1031-2

1031-2

1033-2

1033-2

1033-2

1033-2

1038-2

1038-2

1038-2

1038-2

1038-2

1038-2

1038-2

1038-2

1043-2

1045-31045-3

1045-3

1045-3

1047-4 1048-2

1048-2

1048-2

1048-2

1048-2 1048-2

1050-4

1052-3

1052-3 1052-3

1052-3

1060-2

1060-3

1061-2

1061-2

1061-2

1061-2 1061-2

1061-2

1061-2

1061-2

1061-2

1062-2

1062-4 1062-4

1063-2

1063-2

1063-2 1067-2

1071-2

1072-3 1078-2

1078-2 1078-2

1078-2

1084-2

1088-2

1088-2

1089-21094-2

1094-2

1111-2

1111-2

1115-2

180-3180-4

182-2

182-2

182-4

195-2 195-2

217-2

217-2

217-2

217-2

217-4

218-2

218-2 218-2

218-2 218-2

218-2

219-2

219-2

219-2

219-2

219-2

219-2 219-2

219-2

219-2

219-2

219-2

219-2

236-2

239-3

239-3

239-3

245-3

245-3

245-3

245-3

245-3245-3

246-2

246-2 246-2

246-2

246-2

246-2

246-2

246-2246-2

247-2

247-2

<Ic(4K;17T;18o)>

Inner Ic(4K;17T;18o)

Outer Ic(4K;17T;18o)

32T spec.

I c(4K

, 17

T, 1

8o),

A

Tape

M4passed with large margin

M3

The 32 T procurements show a very wide range of behavior even though supposed to be identical (each end short samples)

Abraimov WAM-HTS Hamburg

0 20 40 60 80 100 120 140 160 1800

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M3 inner M3 outer M4 inner M4 outer

I c a

t 4.2

K e

xtra

po

late

d to

17

T, A

Ic SF; 77K, A

Self field 77 K does NOT provide good prediction of 4 K high field properties

Q: How do we (or the manufacturer) understand better such scatter?Partial A: in field at 77 K is better………

Abraimov WAM-HTS Hamburg

Lidia Rossi MS thesis

Select 5 from 100….

Lidia Rossi MS thesis

Conductor Ic at 0.5 T, 77 K

M4-151 M4-171-4 M4-142 Comment

B parallel ab 44 A 26 A - lowest 47 A - highest

B parallel c 55 A - highest 42 A 30 A - lowest

microscopy Dense c-axis BZO and ab-plane Re2O3

Fewer BZO c rods and many fewer ab- plane Re2O3

Few c-axis BZO nanorods with dominant ab plane ppts.

TEM by Fumitake Kametani

M4-151

M4-171

M4-142

Conclusion

• Both extrinsic and intrinsic defects control Ic in coated conductors and both types are present.

• In situ REBCO growth, especially with strong vortex pinning defects like BaZrO3 (BZO) is VERY susceptible to local growth perturbations that affect Jc(B, T, q) and Ic(x)

• The right tools – multiple ones – are needed to sort them out