Recent Developments in YBCO for High Field Magnet Applications

Transcription

1 superior performance. powerful technology. Recent Developments in YBCO for High Field Magnet Applications D.W. Hazelton Principal Engineer, SuperPower, Inc Low Temperature Superconductor Workshop November 11-13, 2008, Tallahassee, FL SuperPower, Inc. is a subsidiary of Royal Philips Electronics N.V.

2 2G HTS In-field performance improving with enhanced pinning 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 Angle measured relative to a, b plane (90 deg // c) Process parameter window being established for reproducible fabrication Critical current (A/cm-width) standard conductor performance others w/ enhanced pinning K, 1T 0.7 micron SmYBCO 0.7 micron GdYBCO 0.7 micron Zr:GdYBCO Angle (degree) 1

3 New coils in 2008 with Zr-doped (Gd,Y)BCO 2G with improved in-field performance in LN coil Coil ID (mm) clear coils Winding ID (mm) coil 2008 coil Wire Ic (A) 4 mm a) 72 to 97 b) > 90 Winding OD (mm) Coil Height (mm) # of double pancakes 2G tape used (m) # of turns ~ 87 ~ ~ 462 ~ 2772 ~ 87 ~ ~ 480 ~ 2664 Coil Je (A/mm 2 ) per amp of operating current ~1.569 ~1.635 Coil constant (mt/a) ~ 44.4 ~ coil a 2

4 30% higher field achieved from 2G with improved in-field performance (2008a) 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 a-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 4.2 K to be measured 9.8 T / 26.8 T* *in 19T background 3

5 Ic/Ic(0) SuperPower 2G HTS tolerates high axial stress up to 700 MPa 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 Fatigue testing to 100,000 cycles shows no degradation up to 700 MPa (σ min /σ max = 0.1) 4

6 Universal model being developed to look at coil heating, quench initiation Universal Curve for 2G Conductor, H//c Temp (data set) 83K (8) 82K (1) 77K (1) 77K (4) 77K (5) 77K (7) 77K (9) 75K (6) 72K (1) 65K (1) 65K (9) 60K (8) 54K (8) 50K (1) 50K (2) 50K (4) 50K (7) 50K (9) 45K (1) 45K (9) 42K (8) 40K (2) 33K (9) 30K (2) 30K (4) 22K (9) 20K (2) 20K (7) 15K (2) 14K (9) 10K (2) 10K (7) 4.2K (3) 4.2K (6) 4.2K (9) Jc / Jco Data Set 1: PB Data Set 2: PB Data Set 3: PB Data Set 4: PB C Data Set 5: 1217 Data Set 6: PLee/LANL 1996 data Data Set 7: PB Jc(θ) min Data Set 8: ONRL meas "std" cond Data Set 9: SP release 11/ H / H irr 5

7 Universal model being developed to look at coil heating, quench initiation Top = K 30 Ic(Bφ,T) / Ic(sf, 77K) 7 6 Ic(B,T) / Ic(sf,77K) field angle φ (deg) 6

8 Universal model being developed to look at coil heating, quench initiation Coil H2 - Iop / Ic Plot Ic (77, sf) = 80 A, Iop = 60 A, Top = 50 K Iop / Ic radial position (cm) Low Temperature axial position Superconductivity (cm) Workshop

9 Universal model being developed to look at coil heating, quench initiation Coil H2 - Iop / Ic Plot Ic (77, sf) = 80 A, Iop = 60 A, Top = 60 K Iop / Ic radial position (cm) axial position (cm)

10 Questions? Thank you for your interest! For further information about SuperPower, please visit us at: or 9

11 BACKUP 10

12 2G HTS has excellent performance over a wide field and temperature range I c /I c (77K, 0T) vs. Field (perpendicular - B//c) 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) B (T) 11

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

14 NHMFL facilities provide 19T axial background field 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 achieves record performance for highest HTS field, highest magnetic field by a SC magnet Peak hoop stress ~ 215 MPa, well below tape limit Ic of Tapes in Coil 72 A 82 A (77K, sf) 4.2 K Coil Ic - self field 221 A T background self field A 4.2 K Amp Ic- self field 612, K Ic, self field A/mm 2 4.2K Peak Radial Ic, self field 3.2 T Central Field (T) A 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) 9.81 T 175 A 485, Current (A) 4.2 K Ic, 19 T background (axial) 4.2 K Peak Radial Ic, 19 T bkgd (axial) 4.2K Central Field 19 T background (axial) A/mm T 26.8 T 14

16 2G HTS wire architecture 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 (current flows in a-b plane) c b a 15

17 SuperPower 2G HTS 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 16

18 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 17

19 SuperPower 2G HTS wire has larger operating stress-strain window compared to other conductors SP 2G HTS - High Je Stress (MPa) "High Strength" 1G HTS - Moderate Je To 0.6%, 700 MPa "Low Strength" 1G HTS - Moderate Je Nb 3 Sn - Moderate Je Strain (%) 18