2G HTS Wires for High Magnetic

Transcription

1 2G HTS Wires for High Magnetic Field Applications Venkat Selvamanickam Department of Mechanical Engineering Texas Center for Superconductivity University it of Houston, Houston, TX, USA SuperPower Inc, Schenectady, NY, USA 1

2 2G HTS wire : Great potential for applications Second-generation (2G) HTS- HTS is produced by thin film vacuum deposition on a flexible nickel alloy substrate in a continuous reel-to-reel process very different from mechanical deformation & heat treatment techniques used for Nb-Ti, Nb 3 Sn and 1G HTS wires Only 1% of wire is the superconductor ~ 97% is inexpensive Ni alloy and Cu Automated, reel-to-reel continuous manufacturing process Quality of every single thin film coating can be monitored on-line in real time! 20μm Cu 40 μm Cu total 2 μmag 1 μm YBCO - HTS (epitaxial) nm Buffer 50μm Ni alloy substrate 20μm Cu

3 2G HTS wires provide unique advantages 2G HTS wires provide the advantages of high temperature operation at higher magnetic fields. Mechanical properties of 2G HTS wires are also superior YBCO (H//c) YBCO (H//ab) NbTi Nb3Sn (Internal Sn) Nb3Sn (Bronze) < 0.1 mm m 20μm Cu 50μm Hastelloy 20μm mcu non-cu Jc ( A/m mm 2 ) Stress (M MPa) High Strength 1G HTS Low Je SP 2G HTS High Je Applied Field ( Tesla ) 200 Low Strength 1G HTSModerate Je Nb3Sn Moderate Je Strain (%)

4 Advantages of IBAD MgO-MOCVD based 2G HTS wires Use of IBAD MgO as buffer template provides the choice of any substrate High strength (yield strength > 700 MPa) Non-magnetic, high resistive (both important for low ac losses) Ultra-thin (enables high engineering current density) Low cost, off-the-shelf High deposition rate and large deposition area by MOCVD enable high throughput Precursors are maintained outside deposition chamber Long process runs (already shown 50+ hours) 2 μm Ag 1 μm YBCO - HTS (epitaxial) ~ 30 nm LMO (epitaxial) < 0.1 mm 20μm Cu ~ 30 nm Homo-epi MgO (epitaxial) ~ 10 nm IBAD MgO YBCO LaMnO nm 50μm Hastelloy substrate 20μm Cu MgO (IBAD + Epi layer) Y 2 O 3 Al 2 O 3 Hastelloy C-276 4

5 Successful scale up of IBAD-MOCVD based 2G HTS wires 500 Critical Curren nt (A/cm) 500 m 2G HTS wire first 400 demonstrated in January (crossed 100,000 A-m) 200 1,000 m 2G HTS wire first 100 demonstrated in July (crossed 200, A-m) Crossed 300,000 A-m in July 2009 with 1,000 m wire. 1,400 m lengths are now routinely produced. High throughput processing (>> Critical Curre ent * Length (A- -m) Position (m) 320, , , , m/h* in IBAD & buffer 160, processes, > 100 m/h* in other 120,000 processes) 80,000 Manufacturing capacity of few 40,000 hundred km/year 0 *4 mm wide equivalent Nov A-m to 300,330 A-m in seven years 595 m 1 m 18 m 97 m 206 m 62 m 158 m Jul-02 Mar-03 Nov-03 Aug m 1,065 m 1,030 m 322 m 427 m Apr-05 Dec-05 Aug-06 Apr m Jan-08 Sep-08 May-09 5

6 Meeting application requirements for HTS wire: Superior performance in operating conditions Application Cables Wind/Off-shore Generators Operating Field (Tesla) Operating Temp. (K) Key requirements Wire needed per device (ka-m) 001t 0.01 to (ac) Low ac losses (ac) 40, to 70 to to 1 (DC) High currents (dc) 2,500,000 1 to 3 30 to 65 In-field I c 2,000 to 10,000 Transformers to 77 Low ac losses 2,000 to 3,000 Fault current limiters to 77 Thermal recovery High volts/cm 500 to 10,000 SMES 2 to 30 T 4 to 50 In-field I c 2,000 to 3,000 Automotive motors 2 to 5 30 to 65 Aerospace 2 to 5 30 to 50 Low ac losses In-field I c 500 to 1,000 Light weight In-field I c 1,000 to 2,000 Magnets/coils 5 to to 40 In-field I c 200 to 2,000 MRI, NMR, HEP, Fusion reactors 5 to K to 30 In-field I c Long lengths Persistent joints ,000+ 6

7 SuperPower-UH 2G wire development strategy SuperPower s technology operations consolidated in Houston which enabled total focus on manufacturing in Schenectady. Manufacturing objectives High yield, high volume operation On-time delivery of high- quality wire Incorporate new technology advancements Technology objectives High performance wires Highly efficient, lower cost processes Advanced wire architectures Successful transition to manufacturing Manufacturing Operations in NY SuperPower Manufacturing at Schenectady, NY Customers SP Houston National Labs Best of both worlds : strong and concentrated emphasis on technology development & manufacturing Technology in Houston UH research staff CRADAs

8 Improved pinning by Zr doping of MOCVD HTS wires 5 nm sized, few hundred nanometer long BZO nanocolumns with ~ 35 nm spacing created during in situ MOCVD process

9 Improved pinning by Zr doping of MOCVD HTS wires Systematic study of improved pinning by Zr addition in MOCVD films at UH. Two-fold improvement in in-field performance achieved! Cr tiical curren nt (A/12 mm ) % 2.5% 5% 7.50% 10% 12.50% 1.0 T, 77 K Angle between field & tape normal ( ) J /cm 2 c (MA/ ) Critical current (A/4 mm) Standard Production wire Enhanced Zr doped production wire c axis Angle between field and c axis ( ) Process for improved in-field performance successfully transferred to manufacturing at SuperPower 9

10 Benefit of Zr-doped wires realized in coil performance Coil properties With Zr doped dwire With undoped dwire Coil ID 21 mm (clear) 12.7 mm (clear) Winding ID 28.6 mm mm # turns G wire used ~ 480 m ~ 600 m Wire I c 90 to 101 A 120 to 180 A Field generated at 65 K 2.5 T 2.49 T Same level of high-field coil performance can be achieved with Zr-doped wire with less zero-field 77 K I c, less wire and larger bore 10

11 Large improvements in in-field I c of Zr-doped d wires at lower temperatures t too B tape 18 K 18 K undoped 40 K 40 K undoped 65 K 65 K undoped l current (A A/cm) Critica Magnetic Field (T) () 100 A/4 mm All data from production wires 100 A/4 mm achieved at 65 K, 3 T in Zr-doped wire compared to 40 K, 3 T in undoped wire 165 A/4 mm achieved at 40 K, 5 T in Zr-doped wire compared to 18 K, 5 T in undoped wire 11

12 Large improvements in in-field I c of Zr-doped d wires at lower temperatures t too (B, T) / J c (7 77 K, 0 field d) K 18 K undoped Retention of 65 K 40 K 18 K 77 K, zero field I 40 K 40 K undoped c 3 T 3 T 3 T 65 K 65 K undoped Undoped wire Doped wire Retention factor of doped wire is higher by K zero-field I c of 2009 undoped wire = 250 A/cm 77 K zero-field I c of new doped wire = 340 A/cm J c 0.10 B tape Magnetic Field (T) Retention factor of doped wire including higher zero field Ic is higher by

13 Superior performance in recent Zr-doped MOCVD production wires in high fields at 4.2K Production wire 1.1 µm thick HTS film I c (77 K, 0 T) = 310 A/cm 1000 T=4.2K Jc, MA/cm T, K J 4.2 K (A/4 mm) T, B wire T, B wire T, B wire 1,219 1, T, B wire 1,073 1,769 I c - 4mm width (A) 100 undoped, B perp. wire undoped, B wire FY'09 Zr-doped, B perp. p wire FY'09 Zr-doped, B wire FY'10 Zr-doped, B perp. wire FY'10 Zr-doped, B wire 1 10 B (T) Measurements by V. Braccini, J. Jaroszynski, A. Xu,& D. Larbalestier, NHMFL, FSU In-field performance of Zr-doped production wires improved by more than 50% in high fields at 4.2 K 13

14 High-Field Magnets demonstrated with 2G HTS wire Coils fabricated by SuperPower and NHMFL Je ~ 300 A/mm 2 Stress levels MPa 14

15 Applications enabled by high-field performance: Superconducting Magnetic Energy Storage (SMES) Energy storage with greater than 97% efficiency. Provides rapid response for either charge or discharge amount of energy available is independent of discharge rating charge and discharge sequence can repeat infinitely without degradation of magnet 2G HTS-based SMES being developed by ABB, SuperPower, UH and BNL through $ 5.2M program funded by ARPA-E (GRIDS: Grid-Scale Rampable Intermittent Dispatchable Storage) 20 kw ultra-high field SMES device with capacity of up to 3.4 MJ based on HTS coils operating at magnetic fields of up to 25 T at 4.2K 15

16 Goals for further performance improvements Two-fold improvement in in-field performance achieved with Zr-doped d wires Further improvement in I c at B c : Now 30% retention of 77 K, zero field value at 77 K, 1 T ; Goal is 50%. Improvement in minimum i I c controlling factor for most coil performance : Now 15 to 20% retention of 77 K, zero field value at 77 K, 1 T ; Goal is first 30% and then 50% Together with a zero-field I c of 400 A/4 mm at 77 K, self field 200 A/4 mm at 77 K, 1 T in all field orientations. Achieve improved performance levels at lower temperatures too (< 65 K) Critical cu urrent (A/cmwidth) Thickness (µm) Goal Critical curr rent (A/4 mm m) x Standard MOCVD based HTS tape MOCVD HTS w/ self assembled nanostructures Goal 77 K, 1 T c axis Angle between field and c axis ( ) 16

17 Multiple strategies to enhance in-field performance : higher I c, more isotropic Superconductor process modification Chemical modifications in MOCVD to modify defect density, orientation and size. Influence of film thickness on in-field I c of Zr-doped films Influence of rare earth type and content Influence of Zr content at fixed rare-earth type and content Influence of other dopants Influence of deposition rate Buffer surface modification buffer prior to superconductor growth Post superconductor processing modification such as post annealing etc. 1 17

18 zero fie eld I c (A/12 mm) Opportunities with rare-earth modifications: Influence of Y+Gd content t 7.5% Zr in all samples Y content = Gd content Y+Gd content varied Y + Gd content to tape (A/12 mm) Ic at 1 T, Critica al current (A A/12 mm) Y0.65Gd0.65 Y0.7Gd0.7 Y0.75Gd0.75 Y0.8Gd T, 77 K Angle between magnetic field and c axis ( ) Critical current can be tuned in desired orientation of magnetic field in application by modifying total rare earth content even with a fixed Zr %! 18

19 Increased nanoscale (Gd,Y) 2 O 3 precipitates along a-b plane with increased rare earth content (Gd,Y) = 1.2 (Gd,Y) = 1.3 (Gd,Y) = 1.4 (Gd,Y) =

20 Thicker (Gd,Y) 2 O 3 precipitates along a-b plane in high (Gd,Y) wires (Y,Gd)1.2 (Y,Gd)1.3 (Y,Gd)1.4 (Y,Gd) T, 77 K c / I c (B=0) I c Angle beteweend field and c axis ( ) TEM by Dean Miller, ANL 20

21 In-field performance of Zr-doped films is drastically modified d by rare earth content t Zr content maintained at 7.5% in all three samples Y 1.2 m) Y0.6Gd0.6 (Y,Gd)1.5 Y T, 77 K Crit tical curren nt (A/12 m c axis Angle between field and c axis ( ) (Y,Gd) nm Multiple controls available to modify pinning performance of 2G HTS wires! 21

22 Higher amperage wires using thicker films 7 6 /cm2) Jc (MA/ Goal Thickness (µm) ent (A/cmh) Critical curre width Thickness (µm) Goal 800 A/cm (= 320 A/4mm) already demonstrated over 1 m by MOCVD 1000 A/cm (= 400 A/4mm) achieved in 2 µm film in short samples using microbridge by PLD at LANL. 22

23 Jc (MA/cm 2 ) Higher amperage wires using thicker films SP M3-714 Research MOCVD Pilot MOCVD Increasing Ic A A/cm A/cm HTS film thickness Critical curr rent (A/cmth) wid Thickness (µm) Goal Address problems with decreasing current density with thickness High currents without significantly increasing film thickness by increasing current density (Jc) Microstructural t improvement (texture, t secondary phases, a-axis, porosity) Pinning improvement (interfacial & bulk defects) Opportunity to reduce factor of two difference between pilot and research MOCVD systems 23 23

24 mm) Critical current (A/12 Critic cal current (A/ /12 mm) Another benefit with thicker films: better in-field performance % Zr, 1 pass 7.5% Zr, 1 pass T, 77 K 160 0% Zr, 3 passes 7.5% Zr, 3 passes 1.0 T, 77 K Angle between field and c axis ( ) Angle between field and c axis ( ) 0% Zr, 2 passes 7.5% Zr, 2 passes 1.0 T, 77 K Angle between field and c axis ( ) Critical curr rent (A/12 mm m) All samples were of composition Y 0.6 Gd 0.6 BCO Improvement in in-field critical current of Zr-doped wires increases with film thickness 24

25 Critica al current (A/12 mm) Can high-field performance be improved with higher Zr doping levels? Ic Ic Tc 93.0 ΔTc % 5% 10% 15% 20% 25% T c (K K) Critica al current (A/12 mm) % 5% 10% 15% 20% 25% Zr content (%) Zr content (%) ΔT c (K K) Zero-field critical current drops beyond 7.5% Zr addition. Sharper drop in T c beyond 10% Zr addition (3 K from 10% to 25%) Transition width increases by 0.5 K beyond 15% 25

26 In-field Performance at higher Zr doping levels µm film, Y 0.65 Gd 0.65 BCO µm film, Y 0.6 Gd 0.6 BCO 2 mm) ield I c (A/1 Zerof f zero field B ab, 1 T B c, 1 T 0% 5% 10% 15% Zr addition In-fie eld I c (A/12 mm) mm) zero fie eld I c (A/ zero field B c, 1 T B ab, 1 T 0% 5% 10% 15% Zr addition(%) mm) In-fie eld I c (A/12 Best performance at B c with 7.5% Zr. I c at B a-b increases at higher Zr content even with lower zero-field I c Opportunities with high Zr doping levels in B a-b 26

27 New nanowire technologies being developed to target large pinning enhancements Prefabricated nanorods on buffer surface followed by HTS epitaxial growth can allow for independent control of size, distribution and orientation of nanorods. Three techniques developed for prefabricated nanorod growth on LMO on IBAD tapes. 27

28 Targeted improvements in in-field performance of production wires through technology t (A/4mm Critic cal curren )77 K, 0 T K, 15 T 20 K, 10 T 30 K, 5 T K, 5 T 65 K, 3 T t ) ng curren e (A/mm 2 ) Engineerin density, Je 0 0 Now fold improvement by combination of higher self-field critical current and improved retention of in-field performance through technical innovations. Even at 4.2 K, 15 T, 2G HTS wire is comparable now with Nb 3 Sn wire. Opportunity to improve to be 10X better than Nb 3 Sn! 28

29 Multfilamentary 2G HTS tapes for low ac loss applications Filamentization of 2G HTS tapes is desired for low ac loss applications. So far, there is no proven technique to repeatedly create high quality mulfilamentary 2G tapes. Also, adds substantial cost. ac loss (W/m ) 2 1 unstriated 100 Hz 5.1 x multifilamentary B ac rms (T) 4 mm 5-filament tape, 4 mm wide (produced up to 15 m) 32-filament tape, 4 mm wide (difficult to make even 1 m lengths) 29

30 Goals in multifilamentary 2G HTS wire fabrication Maintaining filament integrity uniform over long lengths (no Ic reduction) Striated silver and copper stabilizer (minimize coupling losses) Minimum reduction in non superconducting volume (narrow gap) and fine filaments Ag HTS Substrate Cu A fully filamentized 2G HTS wire would need to have µm of copper stabilizer striated! 30

31 Approach to make fully-filamentized 2G HTS wire Cu Ag HTS substrate 100 μm Cu 1 mm Fully-filamentized 2G HTS wire demonstrated, but still involves etching X. Zhang and V. Selvamanickam, US 7,627,

32 Etch-free process developed to fabricated multifilamentary wire with fully striated stabilizers 12-filament wire with 10 µm thick fully striated copper stabilizer 32

33 Significant ac loss reduction in multifilamentary wire with fully striated stabilizers Critical current of standard wire = 207 A Critical current of 12- filament wire = 197 A Critical current of 12- filament wire after 10 µm copper stabilizer = 200 A AC loss of 12-fiament wire at c loss (W W/m) a 1.E+01 1.E+00 1.E-01 1.E-02 1.E-03 1.E-04 1.E Hz Multfilamentary Standard Multifilamentary + Cu Standard + Cu 60 Hz is 11 times lower than that of unstriated wire without copper stabilizer and 13 times ac magnetic field (T) lower with copper stabilizer, at higher fields 33

34 Significant ac loss reduction in multifilamentary wire with fully striated stabilizers (W/m) ac loss 1E+01 1.E E+00 1.E-01 1.E-02 1.E Hz Multifilamentary Standard ac loss (W W/m) Multifilamentary + Cu 4 Standard + Cu 1.E ac magnetic field (T) T Multfilamentary Standard Multfilamentary + Cu Standard + Cu ac field frequency (Hz) AC loss of 12-fiament wire at 300 Hz is 11 times lower than that of unstriated wire with and without copper stabilizer AC loss of 12-filament wire unchanged with copper stabilizer unlike standard wire; 11 to 13 times lower losses at all frequencies 34

35 Key 2G HTS wire metrics attractive for high magnetic field applications Piece lengths: 1,000 m demonstrated with minimum Ic of ~ 300 A/cm 1,400 m routinely processed m typical Critical current in production wires 325 A/cm available in long lengths ( m) 810 A/cm (J = 2 e 810 A/mm ) at 4.2 K,10 T, field perpendicular to wire 480 A/cm (J e = 480 A/mm 2 ) at 4.2 K, 20 T, field perpendicular to wire 1855 A/cm (J e = 1855 A/mm 2 ) at 4.2 K, 10 T, field parallel to wire Critical current in R&D wires 800 A/cm demonstrated in 1 m lengths Plenty of opportunities for 10x improvement in production wire performance at low temperatures & high fields. Goal of J e = 6000 A/mm 2 at 4.2 K, 15 T perpendicular to wire (~ 10x Nb 3 Sn performance); 1000 A/mm 2 at 40 K, 15 T perpendicular to wire 35

36 Key 2G HTS wire metrics attractive for high magnetic field applications Superior mechanical propertiesp Yield strength > 700 MPa with superalloy-based 2G HTS wire Tensile and bend strains > 0.4% without performance degradation Intense R&D to improve transverse stress properties Joints Joint resistance of nano-ohm cm 2 typical Opportunities for persistent joint fabrication (challenge is in fabrication by magnet manufacturer in the field) AC losses Multfilamentary wires feasible way to reduce ac losses Scalable processes being developed for fully striated multfilamentary t wires 36