Superconductivity UK Commercial superconductors for motors and generators

Superconductivity UK Commercial superconductors for motors and generators Dr. Philip Sargent, Diboride Conductors Ltd.

Commercial Wire & Tape • Commercial production: • Niobium alloys (Nb. Ti, Nb 3 Sn etc) • B 2223 / silver tape - 1 st Generation HTS • Pre-commercial: • Mg. B 2 • Industrial laboratory: • YBCO 2 nd Generation HTS “coated conductor”

Superconductors Hg. Ba 2 Cu 3 O 9 (under pressure) 160 140 Tl. Ba. Cu. O Transition temperature (K) 120 Liquid Methane LNG (112 K) B 2223 - Bi 2 Sr 2 Ca 2 Cu 3 O 100 YBCO - YBa 2 Cu 3 O 7 Liquid Nitrogen (77 K) 80 60 40 20 (La, Ba) Cu) Hg Pb Nb 1910 Leigh Jarvis Tl, Hg…(138 K) Hg. Ba 2 Cu 3 O 9 Nb. C Nb. N 1930 Nb 3 Sn Mg. B 2 Nb 3 Ge V 3 Si 1950 1970 1990

More superconductors YPd 2 B 2 C Ho. Mo 6 S 8 (Chevrel) Er. Rh 4 B 4 Ce. Ru 2 heavy fermion 1991 - K 3 C 60 Fullerene 1994 - Sr 2 Ru. O 4 2001 – Mg. B 2 2001 - C nanotubes 2002 - Pu. Co. Ga 5 (18 K) 1980 - (TMTSF)2 PF 6 Nature 6 Mar. 2003 - Na 0. 35 Co. O 2 • 1. 3 H 2 O

HTS –complex copper oxides B 2223 - Bi 2 Sr 2 Ca 2 Cu 3 O YBCO - YBa 2 Cu 3 O 7

HTS –perovskite ceramics Ba Cu O Y Ba B 2223 - Bi 2 Sr 2 Ca 2 Cu 3 O YBCO - YBa 2 Cu 3 O 7

Engineering Implications • Requires near single-crystal microstructure by complex processing, • Oxide requires furnace treatment in controlled oxygen atmosphere, in silver, • Highly anisotropic resulting tape: • Along and across tape, • Sensitive to magnetic field direction!

B 2223 multifilamentary tape -1 • Fill silver tube with precursor powders. • Reduce by extrusion, swaging, drawing and rolling to a mono filament alignedcrystal wire. • Restack bundle in another silver tube.

B 2223 multifilamentary tape -2 • • Draw multifilament Draw to align crystals Roll to tape Furnace heat treat

AMSC & Sumitomo • AMSC & Sumitomo have a reciprocal American Superconductor 55 filament (B 2223) tape licensing agreement Sumitomo (B 2223) tape

AMSC B 2223 Manufacturing Plant § Larger billets, Process automation, Longer strands, Multi-dies, Faster line-speed, Combination of process steps § Began volume production in early 2003 § Full capacity could be 20, 000 km/year, now 900 km/year

(B 2223) Critical Currents 2001 -02 Manufacturing variability 32 30 28 > 150 m lengths Manufacturing Campaign for Detroit Edison Manufacturing Campaign for Customer X (2002) 26 24 22 Frequency 20 18 16 14 12 10 8 6 4 2 0 103 105 108 110 113 115 118 120 123 125 128 130 133 135 138 140 143 145 148 150 End to End Critical Current, Amps 170 A also demonstrated in short lengths

B 2223 Wire Improvement 21 20 Jc (A/cm 2, 77 K, 0. 1 T, //c) 19 Measured at AMSC and UW Measured at AMSC & University of Wisconsin 18 17 16 15 14 13 12 1994 1995 1996 1997 1998 1999 2000 2001 2002 n Jc of 19. 8 k. A/cm 2 (77 K, 0. 1 T, //c): a new level of performance for wire //c): with production architecture n Measurement in 0. 1 T field avoids self-field current suppression

Current Distributions in B 2223 180 k. A/cm 2 Regions Observed in AMSC Monocore Tapes Headroom for Further Current Density Progress (U. Wisconsin/AMSC)

AMSC B 2223 Plant History • Development started in summer 1988 • 10 years (1998): • • • AMSC produces 20 km in 200 m lengths with an average current of 90 A at 77 K 14 years: 900 km/y plant fully operational 15 years: 900 km/y plant & B 2223 IPR value of $22 m written off !

Price/Performance $/k. A. m • How much does it cost to buy the wire to carry 1000 Amps a distance of 1 m? • Copper: 6 $/k. A. m – 22 $/k. A. m depending on current density (400 – 100 A/cm 2) • Superconductors typically quoted at Jc and at 77 K and either zero magnetic field or “self field”. • Cryogenic OFHC copper can be 0. 06 $/k. A. m. • Nb. Ti is approx. 0. 9 $/k. A. m in liquid helium.

Price/Performance $/k. A. m Price/Performance Ratio, $/k. A-m 1200 $/k. A. m 1000 800 600 World’s First HTS Wire Manufacturing Plant Opened By AMSC 400 200 0 1995 200 $/k. A. m 1996 1997 1998 1999 2000 2001 2002 2003 2004 Reduced Manufacturing Costs ($/m) and Increased Wire Performance (current carrying capacity)

B 2223 & Commercial Products • At $50/k. Am (77 K) price/performance ratio significant markets would be enabled (it was thought in ~1999): − − − Utility Generators (>100 MVA) Ship Propulsion Motors and Generators (>5 MW) Wind Turbine Generators (>4 MW) Urban T&D Power Cables Industrial Magnetic Processing Bought and shut down by AMSC in 2002 • Significant worldwide industry in B 2223 American Superconductor, Innova, Nordic Superconductor, Sumitomo Electric, Vacuumschmelze, Trithor

Magnetic Field • High magnetic field reduces current carrying capacity • Lower temperatures enhance current carrying capacity • B 2223 must operate 20 K – 40 K for motors which have fields ~ 2 T • B 2223 at 27 K carries twice the current, so $/k. A. m reduces to 100 $/k. A. m.

Saturation in Fe-3%Si at 1. 6 T Flux Density, B (T) 1. 6

MA/cm 2 Peter Lee’s Cosmic Plot (UW/ASC) 10 1. 6 T 1 0. 01 0. 001 Power Apps 30 – 77 K Copper: up to 400 A/cm 2

Key issues for power applications • Overall current density • Cost! Je of conductor, not just of superconductor • Performance in field • Multiple filaments for AC applications • Anisotropy of Jc with respect to field direction • Conductor itself • Cooling (AC losses) • Scalability of fabrication • Mechanical • Strength, bend radius • Conductor shape • tape or wire • or new motor designs

Diboride & YBCO • YBCO and similar compounds have had research worth $$billions devoted to their physics and processing. • Mg. B 2 was discovered in January 2001; physics now entirely understood. • Both can be made in: • Tape geometry • Massive lumps for new motor designs

Magnesium Diboride Mg B s Mg B Mg 39 K p

Magnesium Diboride ~ 400 $/kg

Making Diboride tape Tube filling with Mg. B 2 reacted powders Wire drawing and/or rolling Flat rolling Long lengths can be now fabricated Cu-sheathed tape transverse cross irregular cross section Simple sintering ~700 C

PIT Processing routes for the fabrication of Mg. B 2 wires B a) Mg + Mg. B 2 IN-SITU EX-SITU b) tube filling draw to wire reaction sintering IN-SITU 23% porosity EX-SITU simple sintering 100 m lengths of tape

Powder in Tube Swege F = 3. 85 mm P. I. T. Fin= 5 mm Ball milling under Ar Fout= 8 mm P. I. T. Mg. B 2 Flat rolling Tape 4 x 0. 38 mm 2 Draw F = 2 mm Final Tape Flat rolling Université de Genève

Hyper. Tech CTFF for Mg. B 2 CONTINUOUS TUBE FORMING AND FILLING (CTFF)

Irreversibility field • Increase magnetic field capability by metallurgy • Create pinning defects by controlled alloying of Mg. B 2 L. Cowey et al. , Mg. B 2 + yttria

Texas Center for Superconductivity and Advanced Materials University of Houston NASA Commercial Space Center TCSAM 10 -Meter Long Square Mg. B 2 Wire

Strain Effect on Mg. B 2 long tape 100 h ball milled Modified Walters Spiral (WASP) Mg. B 2 Tape Strain gauges d=26 cm Université de Genève

In situ B+Mg with Fe barrier in Monel Sheath With iron –tough to make multifilament- most likely be cabled , (twisted) monofilaments for low AC loss conductor, working on Outer sheaths of Monel, Cu/Ni, and Cu to improve stabilization. Hyper Tech Research

Reasonable properties can be obtained with all Cu wires, Or with Nb barriers in Cu. Multifilament wires can be made Hyper Tech Research

Shows ITER barrel wound with over 1 meter of Mg. B 2 wire, all Cu sheath, 1. 00 mm diameter wire. The self field transport current for the coil at 4. 2 K was 450 amps, the estimated transport current at 20 K would be 150 -180 amps. Hyper Tech Research

First test of an Mg. B 2 pancake Critical Current [A] 250 Mg. B 2 pancake BSCCO pancake 200 150 4. 2 K BSCCO 100 50 0 Mg. B 2 3. 0 3. 5 4. 0 Magnetic Field [T] 4. 5 5. 0

MA/cm 2 Peter Lee’s Cosmic Plot (UW/ASC) 10 1 Genoa 25 K 0. 1 0. 001 Power Apps 30 – 77 K

Magnesium Diboride (Mg. B 2 ) • Advantages • No weak-link effects, low anisotropy • Easy to fabricate wires, films: <$10/k. A. m potential • Challenges • Tc < 40 K (77 K applications like cables, transformers not viable) • High field applications such as NMR not viable • Possible applications in 20 -30 K range for modest field environments, e. g. , rotating machinery

YBCO Coated Conductor • Rolled, textured Nickel tape (Ni-W) • Oxide buffer layer, preserves texture • YBCO (or analogue, e. g. Ho. BCO), preserves texture • Near “single crystal” 100 s of metres long • <$10/k. A. m potential

YBCO Coated Conductor Sumitomo YBCO-CC

YBCO Ni tape Oxide buffer layer deposition

YBCO precursor YBCO oxygenation and conversion

YBCO Slitting

YBCO Coated Conductor tape • Active programs in US, Japan and Europe • Examples of results in 2001: • 122 A (75 K) over 1 m by LANL − World record for meter length • 50 A over 10 m by Fujikura − World record for 10 meter length • Over 60 m : Fujikura 1. World’s longest processed tape

Comparative Development • YBCO CC • • Fujikura announces YSZ-IBAD process, early 1991 Ten years later (2001): • Fujikura produces 10 m with 50 A (77 K) • B 2223 • • Work started in summer 1988 Ten years later (1998): • AMSC produces 20 km at minimum 200 m piece length with an average current of 90 A (engineering current density 11, 000 A/cm 2 at 77 K)

YBCO CC Technical Issues • Adequate uniformity over length • Stability to over-currents or cracks • Adequate current in MOD films • Mechanical properties – spalling, cracking • Stability of metal-oxide epitaxial interface • Deposition rate for ion beam and laser processes • Thicker than 3 micron YBCO ? • …but must have that 10 $/k. A. m process!

B 2223 (1 G) to YBCO (2 G)

Price/Performance $/k. A. m Price/Performance Ratio, $/k. A-m 1200 $/k. A. m 1000 800 600 World’s First HTS Wire Manufacturing Plant Opened By AMSC 400 200 0 1995 200 $/k. A. m 1996 1997 1998 1999 2000 2001 2002 2003 2004 Reduced Manufacturing Costs ($/m) and Increased Wire Performance (current carrying capacity)

AMSC 2 G Plant • 25 th Sept. 2003 • ORNL award of $2. 5 m to AMSC to commercialise 2 G process • 1 st October 2003 • First tranche of $10 m from US Do. D and DOE to build 2 G plant for YBCO-CC tape over 3 years. • 3 rd October 2003 • $44 m share issue priced to be used to build 2 G plant • but all committed on pre-commercial processes!

Performance Technology ‘S’ Curves Effort

Power Technologies HTS g 2 Performance 75 y 17 y Mg. B 2 HTS g 1 Copper-Iron 2003 Effort

Conclusions: Superconductors for Motors • HTS G 1: • B 2223 tape • Diboride: • Mg. B 2 wire • Mg. B 2 HIPped bars • HTS G 2: • YBCO CC tape • YBCO cast crystals