Continued Developments in High Magnetic Fields Enabled by Second-Generation High- Temperature Superconductors

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1 superior performance. powerful technology. Continued Developments in High Magnetic Fields Enabled by Second-Generation High- Temperature Superconductors Drew W. Hazelton - Principal Engineer, HTS Applications 2009 Magnetics Conference Chicago, IL April 15-16, 2009 SuperPower, Inc. is a subsidiary of Royal Philips Electronics N.V.

2 Acknowledgements SuperPower Jason Duval, Venkat Selvamanickam and the rest of the SuperPower Team Program funding from Title III and DOE through UT-Battelle, the Air Force Research Laboratory and the Office of Naval Research National High Magnetic Field Laboratory / FSU David Larbalestier, Denis Markiewicz, Huub Weijers and the rest of the NHMFL/FSU team Supported through funding from NSF, the State of Florida and by the DOE Naval Research Laboratory Ron Holtz Supported through funding from the Office of Naval Research 1

3 Superconductor: How do we make SuperPower 2G HTS wire? Uniform thickness Substrate Electropolishing Silver Sputtering Substrate: Smooth and Clean Buffer: Good Texture Copper Electroplating Buffer IBAD HTS MOCVD Superconductor: Composition 2

4 2G HTS wire properties drive coil advancements SuperPower s 2G HTS wire is based on high throughput IBAD MgO and MOCVD processes. Use of IBAD as buffer template provides us choice of any substrate. Advantages are: high strength, low ac loss (non-magnetic, high resistivity substrates) and high engineering current density (ultra-thin substrates) 2.66 A/mm 2 per A of operating current 3

5 2G HTS wire has excellent performance over a wide field and temperature range I c /I c (77K, 0T) vs. Field (perpendicular) K (Sample 1) 14 K (Sample 1) 22 K (Sample 1) 33 K (Sample 1) 45 K (Sample 2) 50 K (Sample 2) 65 K (Sample 2) 77 K (Sample 2) Ic (H//c)/Ic (77K 0T) H (T) 4

6 2G HTS in-field performance improving with enhanced pinning within (RE)BCO structure In-field performance vs. field angle drives coil design and performance Critical region for coil is degrees Significant drop off in Ic Relatively large field component New wire with enhanced pinning becoming available Critical current (A/cm-width) micron SmYBCO micron GdYBCO micron Zr:GdYBCO K, 1T Angle (degree) 5

7 Thin-profile Wire (50 micron substrate) exhibits superior bend properties in joints Copper stabilizer solder YBCO substrate Lap Joint Bridge Joint 4 mm wide conductors each with 20 μm surround copper stabilizer Joint or splice length = 3 or 3.5 cm Original tape thickness = mm Thickness at joint or splice = 0.22 mm (~ 2 times thinner that with 1G or other 2G!) No degradation in Ic (1 μv/cm) over the joint or splice Joint or splice resistivity = 40 to 50 nωcm 2 (<100 nano-ohm in a typical splice) No degradation in Ic and resistivity when joint or splice is bent over down to 1 diameter and thermal cycled three times. Ic was tested at every thermal cycle No issues with soldering 6

8 SuperPower 2G HTS wire has superior mechanical strength 77K Yield Stress 970 MPa Strain at yield 0.92% Superpower 4mm Wide 2G-HTS Tape Stress-Strain Curves at Room Temperature and 77K Tape ID # M BS M K 800 Stress [MPa] Room Temperature 0048.RT 0083.RT 0099.RT RT LN LN LN 0 0.0% 0.5% 1.0% 1.5% 2.0% Strain [%] Data from R. Holtz, NRL 7

9 SuperPower 2G HTS wire tolerates high axial stress up to 700 MPa Ic/Ic(0) Ic/Ic(0) Versus Stress at 77K Tape ID # M BS M Peak Stress 0048 Unloaded Peak Stress 0115 Unloaded Peak Stress 0163 Unloaded Recommended Stress Limit Stress [MPa] Data from R. Holtz, NRL Ic drops by up to 10% reversibly under peak stress up to 700 MPa (about 0.6% strain) Above 700 MPa (0.6% strain) Ic degrades irreversibly N-value does not change with peak stress up to 700 MPa N-value degrades irreversibly coincident with irreversible Ic degradation Define σ IcRL (ε IcRL ) = Ic Reversiblity Limit = Peak monotonic stress (strain) for >98% reversibility of Ic σ IcRL (ε IcRL ) = 700 MPa (0.6%) 8

10 Fatigue strength equivalent to Ic reversibility limit Fatigue-Life at 77K Superpower 2G Tape ID M BS Tension-Tension Cyclic Loading at Stress Ratio (min/max) = 0.1 Peak Stress [MPa] Ic drops below 98% Mechanical Failures Recommended Critical Stress for 100% Ic Retention Runouts Runouts are specimens that did not degrade either mechanically or electrically up to 100,000 cycles Load Cycles 1,000 10, ,000 Data from R. Holtz, NRL 9

11 2G HTS has favorable thermal expansion characteristics 2G HTS (SCS4050) Iron / steel G10 warp 304 SS Copper Brass ( ΔL / L o ) Temperature (K) 10

12 SuperPower 2G HTS wire has larger operating stress-strain window compared to other conductors Stress (MPa) SP 2G HTS - High Je "High Strength" 1G HTS - Moderate Je "Low Strength" 1G HTS - Moderate Je Strain (%) Nb 3 Sn - Moderate Je 11

13 SuperPower 2G HTS offers distinct advantages in critical current performance over conventional LTS conductors at high fields Superconductor Critical Currents Non-Cu Critical Current Density (A/mm 2 ) K NbTi MBG avg NbTi Industry Avg Nb3Sn OST Bronze Nb3Sn OST Internal Sn YBCO 2007 (H//c-radial) YBCO 2007 (H//a,b-axial) YBCO 2012 (H//c-radial) YBCO 2012 (H//a,b-axial) Applied Field (T) 12

14 NHMFL facilities provide 19T axial background field for 26.8 T world record measurement Insert coil tested in NHMFL s unique, 19-Tesla, 20-centimeter wide-bore, 20-megawatt Bitter magnet 2G HF Insert Coil Showing Terminals, Overbanding and Partial Support Structure. Flange OD is 127 mm. 13

15 High field insert coil demonstrated Wire: Dimensions: 4 mm wide x 95 microns thick Substrate: 50 micron Hastelloy HTS: ~1 micron YBCO Stabilizer: ~2 micron Ag on YBCO Coil ID Winding ID Winding OD 9.5 mm (clear) 19.1 mm ~ 87 mm Wire Ic ~20 microns of surround copper stabilizer per side A, 77 K, sf Coil Height ~ 51.6 mm # of Pancakes 12 (6 x double) Coil Winding Double Pancake Construction Dry Wound (no epoxy) Kapton polyimide insulation (cowound) 2G wire used ~ 462 m # of turns ~ 2772 Coil Je ~1.569 A/mm 2 per A Coil constant ~ 44.4 mt/a Overbanding: 316 Stainless Steel 14

16 High field insert coil achieves record performance for highest HTS field, highest magnetic field Ic of Tapes in Coil by a SC magnet Central Field (T) Peak hoop stress ~ 215 MPa, well below tape limit 19T background self field A A 72 A 82 A (77K, sf) 4.2 K Coil Ic - self field 221 A 4.2 K Amp Ic- self field 612, K Ic, self field A/mm 2 4.2K Peak Radial Ic, self field 4.2 K Central field self field 4.2 K Coil Ic 19 T background (axial) 4.2 K Amp Ic 19 T background (axial) 3.2 T 9.81 T 175 A 485, K Ic, 19 T background (axial) A/mm Current (A) 4.2 K Peak Radial Ic, 19 T bkgd (axial) 4.2K Central Field 19 T background (axial) 2.7 T 26.8 T 15

17 New coil in 2008 with Zr-doped (Gd,Y)BCO 2G with improved in-field performance in LN coil Coil ID (mm) clear coil 2007 coil 2008 coil Wire Ic (A) 4 mm to 97 Winding ID (mm) Winding OD (mm) Coil Height (mm) # of double pancakes 2G wire used (m) # of turns 19.1 ~ 87 ~ ~ 462 ~ ~ 87 ~ ~ 480 ~ 2664 Coil Je (A/mm 2 ) per amp of operating current ~1.569 ~1.635 Coil constant (mt/a) ~ 44.4 ~

18 30% higher field achieved with 2G with improved in-field performance Ic (A) for 4 mm wide wire (Y,Sm)BCO wire 2007 coil (Y,Sm)BCO wire 2007 coil Zr:(Gd,Y)BCO wire for 2008 coil Zr:(Gd,Y)BCO wire for 2008 coil 75 K, 0.92 T (LANL) 77 K, 1 T (ORNL) Angle between field and wire (degrees) Temperature Coil current Max Central Field (K) (A) (T) Temperature 2008 coil with Zr-doped (Gd,Y)BCO 2007 coil with (Y,Sm)BCO Improvement 77 K 0.95 T 0.73 T 30% 65 K 2.39 T 17

19 2008 NHMFL coil demonstrates 33.8 T in 31 T background field Fabricated with 4 mm wide commercial SuperPower wire Reference: Tests of HTS Insert Coils Above 30T, H.W. Weijers et. al. (NHMFL) ISS Tsukuba, Japan, Oct

20 Summary We have not reached the limit of 2G HTS wire capability 2G HTS wire with 50 micron Hastelloy substrate enables high winding pack Je 2G HTS wire is available in lengths and quantity to enable development in high field magnet design and construction T (and beyond) is within our grasp 19

21 Questions? Thank you for your interest! For further information about SuperPower, please visit us at: or 20