MgB 2 and BSCCO. S.I. SCHLACHTER, W. GOLDACKER KARLSRUHE INSTITUTE OF TECHNOLOGY, INSTITUTE FOR TECHNICAL PHYSICS

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1 MgB 2 and BSCCO S.I. SCHLACHTER, W. GOLDACKER KARLSRUHE INSTITUTE OF TECHNOLOGY, INSTITUTE FOR TECHNICAL PHYSICS KIT University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association

2 Contents Situation for MgB 2 materials (commercial) and cables BSCCO(2223) cables BSCCO(2212) cables Conclusions 2 26/ Wilfried Goldacker HTS4Fusion WS KIT

3 Current carrying capability of LTC and HTS wires at lhe 3 26/ Wilfried Goldacker HTS4Fusion WS KIT

4 The interest in MgB 2 is better temperature margin than LTS, expected possible upgrade of transport currents and low costs!!! Nb 3 Sn YBCO B irr [T] 10 NbTi Coils for Fusion Reactors Bi2223 MgB 2 0 LHe LH 2 LNe LN 2 pumped LN Temperature [K] 4 26/ Wilfried Goldacker HTS4Fusion WS KIT

5 Examples of MgB 2 conductors for cables PIT manufactering in length exceeding 1 km (industry) HyperTech Research Inc., USA IEE, Bratislava Cu-30Ni Cu MgB 2 Nb Fe AgMg Nb Columbus Superconductors srl, Genoa: Karlsruhe Institute of Technology SS Fe SS SS Nb Fe Cu MgB 2 Cu Fe Ni Round wires are very suited for assembling cables, speciality of KIT are thin wires, down to 0.25 mm! 5 26/ Wilfried Goldacker HTS4Fusion WS KIT

6 Commercial availability of MgB 2 conductors I Columbus Superconductors srl, Genua Length: ~1-5 km Total Production: 2007: 100 km 2008: 300 km anticipated Standard: Ex-Situ 14 Filaments I c (A) tape 14 fil-perp wirea-19 fil wireb-19 fil wirec-19 fil wired-37 fil wiree-19 fil 1 T = 4.2 K B (T) 6 26/ Wilfried Goldacker HTS4Fusion WS KIT

7 Commercial availability of MgB 2 conductors II HyperTech Res., Columbus Ohio Diameter mm (and others) In-situ-route Filament number 7 and 19 (higher filament numbers experimentally) State Reacted and unreacted, insulated with s-glass Heat Treatment 700 C / 20 minutes (nominal) Critical Current Density, J c, A cm NbCu19+M A (700-20) NbCu19+M C (700-20) NbCu19+M D (700-20) NbCu19+M E (700-20) NbCu19+M G (700-20) 10 5 NbCu19+M H (700-20) NbCu19+M I (700-20) NbCu19+M J (700-20) NbCu19+M M (700-20) NbCu19+M N (700-20) J 20 K 2T Max. axial strain tolerance Continuous length Superconductor fraction 175,000 A/cm 2 (nominal) 0.35% 1-4 km 13 18% (30% under development) Magnetic Field, B, T At 4.2 K and 4 T: J c = x 10 5 A cm -2 At 4.2 K and 8 T: J c = x 10 4 A cm / Wilfried Goldacker HTS4Fusion WS KIT

8 Coming to assembled wires: cable concepts 8 26/ Wilfried Goldacker HTS4Fusion WS KIT

9 MgB 2 Cables at FZK (Status): Possibilities: Continuous cabling Easy control of twist length Constant winding angle Constant strand tension Addition of Cu wires Cable & React Technology Cable & React (C&R) Technique High deformation of sc strands possible Small twist pitches J c,cable ~ J c,wire!!! J c [Acm -2 ] Strand S2: MgB 2 /Nb/Cu/SS Cable C3: 3 x 1 Cable C4: 6 x 1 + Cu B [T] 9 26/ Wilfried Goldacker HTS4Fusion WS KIT

10 Specialities of the KIT cable route Diversity of strands: Thin wires Different sheath composite SS-sheath SS-Nb-sheath In-situ Processing: Cabling of unreacted wires Allows very small twist pitch Flexibility of cable design Suitable for RTR (T < 640 C/ min) No SS softening Suitable for Cu-strands SS-Cu-Nb-sheath 10 26/ Wilfried Goldacker HTS4Fusion WS KIT

11 MgB 2 cables at IEE Bratislava (P. Kovac et al SUST 23 (2010) ) The transport critical current density shows degradation at < micron depending on composite design 1000 A! Also the transport current goes down with filament size, possibly due to geometry sausaging (PIT) and barrier defects 11 26/ Wilfried Goldacker HTS4Fusion WS KIT

12 Examples for MgB 2 cables at IEE Bratislava Institute for Electrical Engineering, Bratislava: I. Hušek et al., Cryogenics 49 (2009) / Wilfried Goldacker HTS4Fusion WS KIT

13 MgB 2 cables R&D at CERN /Columbus: Survey busbar concepts for LHC upgrade (CERN) Design: (MgB 2 -conductors in green) Cable concepts : I = 3 ka I = 14 ka Copper mockups: I = 8 x 0.6 ka I = 7 x 14 ka I = 7 x 3 ka All 4.2K s.f. A. Ballarino, Proceedings EUCAS 2009, Dresden, / Wilfried Goldacker HTS4Fusion WS KIT

14 Conclusions for MgB 2 Suitable so far for medium field range at lhe Limits for reaching small filaments (PIT) High potential for cabling, standard procedures Cheap wires, round wires Good choice for busbars Potential for much higher performance (Geneva!) Cables for >20 ka in magnetic field are very complex, not demonstrated so far! Wires are commercial! 14 26/ Wilfried Goldacker HTS4Fusion WS KIT

15 Contents Situation for MgB 2 materials (commercial) and cables BSCCO(2223) cables BSCCO(2212) cables Conclusions Tapes are commercial! 15 26/ Wilfried Goldacker HTS4Fusion WS KIT

16 ROEBEL bar (CTC) from BSCCO(2223) tapes (Siemens) M. Leghissa et al. Features: In-plane bending of tapes Transposition m 1.18 ka at 77 K s.f. Insulated strands BSCCO(Ag/AgMg) 16 26/ Wilfried Goldacker HTS4Fusion WS KIT

17 Characteristics of CTC- BSCCO-cables (M.Leghissa SIEMENS) Transport AC losses explained assuming monobloc model Filament intergrowths Strong current degradation in self field Typical BSCCO tape (EAS) 17 26/ Wilfried Goldacker HTS4Fusion WS KIT

18 Strong filament coupling from intergrowths AC losses reduced via strand (tape) width! Strong current degradation in self field Characteristics of CTC- BSCCO-cables (M.Leghissa SIEMENS) Transport AC losses explained assuming monobloc model Filament intergrowths Typical BSCCO tape (EAS) 18 26/ Wilfried Goldacker HTS4Fusion WS KIT

19 Performance of BSCCO(2223) and REBCO Normalized Current I c (B,T)/I c (s.f.,77k) K 77 K 50 K 77 K 4.2 K 4.2 K 65 K B Tape 22 K 20 K 50 K B (T) Sumitomo DI-BSCCO 77 K 66 K 50 K 20 K 4 K SuperPower REBCO 77 K 65 K 50 K 22 K 4.2 K Sumitomo DI-BSCCO: SuperPower REBCO: D. Hazelton et al., Recent Developments in 2G HTS Coil Technology - Talk 5LZ01, ASC 2010, Washington DC, Aug. 1-6, 2010 Y.-Y. Xie et al. ; 2009 KEPRI-EPRI Joint Superconductivity Conference, Nov 16-19, 2009 Daejeon, South Korea Better I c (B,T)-performance for REBCO-conductors than for BSCCO (2223) conductors for T K BSCCO(2223) is definitly fixed to a tape structure which is limiting ideas for cable designs in particular with low AC loss structure 19 26/ Wilfried Goldacker HTS4Fusion WS KIT

20 Contents Situation for MgB 2 materials (commercial) and cables BSCCO(2223) cables BSCCO(2212) cables Conclusions 20 26/ Wilfried Goldacker HTS4Fusion WS KIT

21 Hasegawa T, et al. (2001), IEEE Trans. on Appl. Superc., 11, 3034 Strong bridging as result of I c optimization At low temperature the current carrying capacity of (2212) is superior to (2223) 21 26/ Wilfried Goldacker HTS4Fusion WS KIT

22 22 26/ Wilfried Goldacker HTS4Fusion WS KIT

23 Strand performance very sensitive depending on treatment and different filament size & number 23 26/ Wilfried Goldacker HTS4Fusion WS KIT

24 High current AC cable (2212) for accelarator magnets (BNL-Showa-Oxford-Nexans) 24 26/ Wilfried Goldacker HTS4Fusion WS KIT

25 Performance of (2212) Rurtherford cable (Showa electric) 25 26/ Wilfried Goldacker HTS4Fusion WS KIT

26 26 26/ Wilfried Goldacker HTS4Fusion WS KIT

27 BSCCO(2212) Rutherford cable (Korea) S.-C.Kim et al. Estimated current densities 5 K 0.1 T and (10 K 5T) 20 strands: 127 (15) kacm strands: 110 (11) kacm / Wilfried Goldacker HTS4Fusion WS KIT

28 BSCCO(2212) Rutherford Cable (OSU, BNL, IGC, Showa) E.W.Collings et al. Strand with 380 filaments Cables with varied strand coupling best cable current 3.5 ka 28 26/ Wilfried Goldacker HTS4Fusion WS KIT

29 BSCCO(2212) RF Cable, coupling losses for different designs E.W.Collings et al. Alternating NiCr cores cause low coupling Al 2 O 3 plasma-spraying is also insulating One of the rare R&D actions to work on technical issues and a more sophisticated cable design! Coupling losses (at Bm =400 mt) for cables Bi-NC (core of NiCr), Bi-AO-NC (NiCr-core and plasma-sprayed Al2O3 coating), BI-NC- NC (alternating 9 HTS, 9 NiCr strands) 29 26/ Wilfried Goldacker HTS4Fusion WS KIT

30 Summary for BSCCO Rutherford Cables Referenz HTS material I c (4.2K, s.f.) [A] * extrapolated ** at 77 K No. of Strands Transpos. pitch [mm] Filam. / strand I c (4.2K, s.f.) [A] per strand * extrapolated ** at 77 K Cable dimensions Width x hight [mm] (length [m] M.Leghissa Bi(2223) 1180** ** 9 x 2.5 (50) T. Hasegawa Bi(2212) 12000* > x 1.9 (147) Bi(2212) 12000* > x 1.55 (300) S-C. Kim Bi(2212) 3146* * 8.26 x 1.46 (110) Bi(2212) 6960* * x 1.46 (10) E.W.Collings Bi(2212) x 2.73 (5-10) RF BSCCO(2212)-cables exceeded 10 ka at lhe in self field! Long length was demonstrated (200 m) Cable upgrade (> factor 5) for high field specs. possible? Cable design and fabrication with low flexibility (reacted strand, Ag-sheath)? Is the wire an affordable, commercial product 30 26/ Wilfried Goldacker HTS4Fusion WS KIT

31 Conclusions It seems more promising to consider 2G HTS cables for application in Fusion technology Thanks for your attention! 31 26/ Wilfried Goldacker HTS4Fusion WS KIT