Advances in 2G HTS Conductor for High Field Applications

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1 superior performance. powerful technology. Advances in 2G HTS Conductor for High Field Applications DW Hazelton November 5, 2013 LTHFSW 2013 St. Petersburg, FL SuperPower Inc. is a subsidiary of Furukawa Electric Co. Ltd.

2 Acknowledgements We would like to acknowledge the contributions of the team at SuperPower as well as collaborators from around the world. In particular we would like to acknowledge the input from Toru Fukushima, Paul Brownsey, Honghai Song*, Yifei Zhang, Justin Waterman, Trudy Lehner, Hisaki Sakamoto, John Dackow, Ross McClure and Allan Knoll. The work presented here is supported in part with funding from the US DOE Smart Grid Program and ARPA-E. *currently at MSU-FRIB 2

3 Outline SuperPower 2G HTS conductor architecture Critical current status Mechanical properties Bonded conductor development Closing remarks 3

4 Wire performance critical to high field applications I c (B, T, ) Temperature, magnetic field and field orientation dependence of I c Minimum I c at operating condition Mechanical properties (electromechanical performance) Workability for fabrication into various devices Irreversible stress or strain limits under various stress condition, in terms of I c Uniformity along length (I c and other attributes) Thermal properties (thermal expansion coefficient and thermal conductivity) Quench stability (NZPV and MQE) Insulation (material and method) Splices Resistance (resistivity) Mechanical strength (tensile and bending) 4

5 SuperPower s ReBCO superconductor with artificial pinning structure provides a solution for demanding applications Hastelloy C276 substrate high strength high resistance non-magnetic Buffer layers with IBAD-MgO Diffusion barrier to metal substrate Critical texture layer Ideal lattice matching from substrate through ReBCO MOCVD grown ReBCO layer with BZO nanorods Flux pinning sites for high in-field I c Silver and copper stabilization 5

6 I c uniformity along length (TapeStar) Position (cm) (on a 12 mm wide tape) Magnetic, non-contact measurement High spacial resolution, high speed, reel-to-reel Monitoring I c at multiple production points after MOCVD Capability of quantitative 2D uniformity inspection 6

7 I c uniformity along length (four-probe transport measurement) Ic (A, 77K, s.f.) and n-value Position (m) (on a 4 mm wide wire) 7

8 I c (B,T, Φ) characterization is critical to understanding the impacts of processing on operational performance M Lift Factor vs. H//ab, T 65 K 50K 40 K 30K 20K M Lift Factor vs. H//c, T 65 K 50K 40 K 30K 20K Lift Factor [ Ic(H,T)/Ic(sf, T) ] //ab Applied Field (Tesla) Lift Factor [ Ic(H,T)/Ic(sf, T) ] //ab Applied Field (Tesla) Measurements made at the University of Houston Lift factor, I c (B,T)/I c (sf, 77K), particularly a full matrix of I c (B,T, Φ) is in high demand. Frequently sought by coil/magnet design engineer, for various applications. Used to calculate local I op / Ic ratio inside coil body, and design quench protection. 8

9 Significant improvement in lift factor at targeted operating conditions for motor/generator demonstrated 9

10 FEC Nikko test data 4K Ic data Ic test data 4mm samples B//c Ic spread at 15T > 2x A for M3 (8 runs) Tighter Ic spread for M (2 runs) slopes comparable ( ) M4 Ic > M3 Ic 10

11 FEC Nikko test data 77K LF 77K LF test data 4mm samples B//c LF spread at 15T much tighter than earlier NHMFL measurements for M3 (8 runs) Tighter LF spread for M (2 runs) M4 LF > M3 LF 11

12 FEC Nikko test data 4.2K, 5T normalization 4.2K 5T Normalization 4mm samples B//c Tight data spread when normalized to 4.2K, 5T 12

13 Lift factor performance tied to film composition 30K, 3T 774A 807A Similar 4K, 15T analysis in progress 373A 795A 442A 1037A Composition X 13

14 IcBT measurement system being built for routine production sampling Target operating conditions Temperature: 30K 77K Field: 0 2.5T (65K) Higher field operation at 4K Field //c and //ab (rotatable deg) Sample length in field min 25 mm Maximum sample current A Full width samples to 4mm wide Maximum coil current 400A 2G HTS background coils Enables testing of production material in Schenectady (77K- 30K, 0-2.5T) to evaluate consistency of lift factor. 1 4

15 Tensile test of Hastelloy substrates before EP Substrates with various thickness measured for baseline data 1.0mil, 1.2 mil, 1.5mil, 2mil, 4mil from Suppliers A, B 25.4 m per mil

16 Tensile test of wires with SCS Measurement for baseline data Effect of Cu thickness or Cu/Hastelloy ratio Establish data base on tensile stress (strain) limits M (100µm Cu) Stress limit 450MPa M (40µm Cu) Stress limit 600MPa 16

17 Delamination strength studied with peel test P 90 peel test P T-peel test Cu Ag REBCO Buffer Hastelloy Ag Cu Cohesive Adhesive Mixed mode Peeling Load (N) Displacement (mm) Relationship between peel strength and processing conditions established 17

18 Successful winding techniques demonstrated to mitigate delamination issue Decoupling of former from winding has been demonstrated to be beneficial Eliminates radial tensile stress on the 2G HTS windings PET release layer incorporated at former:windings interface Lower thermal expansion formers (Ti, controlled expansion glassepoxy) Alternative insulations/epoxy systems have been successfully demonstrated PET shrink tube - NHMFL Electrodeposited polyimide - Riken Alternative epoxy system with filler - KIT Use of cowound stainless steel as insulation with partial epoxy application on coil sides Mitigates radial tensile stress on the 2G HTS Improves overall coil strength Negative impact on coil current density 1 8

19 Stainless steel insulation, partial epoxy application on coil sides shows resistance to delamination Very thin layer of epoxy (transparent) after epoxy is cured Mechanical fix turn-turn and layer-layer Provides thermal link between optional cooling plates and windings Seals the coil Voltage (V) 1.00E E E E E-03 Five thermal cycles (77K), no degradation found TC#1 TC#2 TC#3 TC#4 TC#5 0.00E E Current (A) 19

20 Alternative epoxy for wet wound coils shows resistance to delamination Design of experiments on Adraldite epoxy with Alumina Epoxy (Araldite DBF): hardener (Araldite 951) = 10:1 A fully wet wound coil Conductor M BS, , 10 meter, 52 turns, ID=2 No additional insulation except for the epoxy, PET release Five thermal cycle, no degradation found [C Barth et al, KIT, SuST. 26 (2013) ] Voltage over 10 meter (V) 1.4E E E E E E E 04 TC#5 TC#4 TC#3 TC#2 TC#1 Ic=42.9A, n-value=~18 Voltage (V) 2.0E E E E E E A/min 10 A/min E Current (A) 1.0E E 03 Current (A) Five thermal cycles, no degradation In TC#5, ramp rate comparison, no difference in Ic and n-value, 42.9A/

21 Capability for bonded conductors demonstrated [higher amperage, specialty applications (FCL) ] Bonded conductors offer the ability to achieve higher operating currents FCL transformer windings HEP applications High current bus applications Bonded conductors offer higher strength Withstand FCL transformer fault currents High field HEP applications with high force loadings Bonded conductors offer the ability to tailor application specific operating requirements, i.e. normal state resistance for a FCL transformer 21

22 Bonded conductors meet target normal state resistance while meeting mechanical strength targets for FCL transformer application] composite resistance / length 70Cu-30Ni mm mm mm mm mm mm mm mm target resistance / length (ohm / m) mm wide C m (RE)BCO 1.0 m silver alloy 4.0 m solder 10.0 m target temperature (K) DOE SMART GRID Project 28 MVA 3-phase FCL Medium Power Utility Transformer (69 kv / kv class) Testing on So. California Edison Smart Grid site in Irvine, CA plan min 1 year of grid operation 22

23 Closing remarks SuperPower 2G HTS conductor offers a flexible architecture to address the broad range of demanding high field applications requirements. SuperPower is engaging major resources in improving its manufacturing capabilities to deliver a consistent, reliable, high quality 2G HTS product Improved mechanical properties Improved piece length / uniformity Improved current density Improved splice resistance Alternative conductor configurations are being developed to address customer specific requirements Ag alloy Bonded conductors 23