Superconductivity for Electric Systems 26 Annual DOE Peer Review July 25 27, 26 HTS Solutions for a New Dimension in Power Superconductivity for Electric Systems 26 Annual DOE Peer Review
Progress in Scale-up of 2G Conductor at SuperPower Venkat Selvamanickam Yi-Yuan Xie Jodi Reeves Program funding from Title III and DOE through UT-Battelle HTS Solutions for a New Dimension in Power Superconductivity for Electric Systems 26 Annual DOE Peer Review
FY6 was the year of transition to Pilot-scale manufacturing: Goals were established accordingly Needed Feature in Commercial 2G High throughput Long lengths with excellent uniformity High Ic in long lengths Reproducibility Quality Control Higher Ic thick films Better in field properties Better mechanical properties Ac loss reduction in long lengths Overcurrent protection Better dielectric properties 2G Prototypes Stated goal for FY6 in FY5 presentation Helix tape handling in all processes; 3 m/h in every step to produce m at A/cm 2 m with Ic of A/cm with 5% uniformity 3 A/cm over m Produce 8 m for Albany Cable project High-speed XRD tool for IBAD MgO buffers A/cm in 2 micron films Je of ka/cm 2 in self field and 25 ka/cm 2 at 1 T, 77 K, using chemical substitution Using thinner substrates, better joints* Demonstrate patterned + twisted conductor Quench testing of coils Dielectric testing 3 T coil at 65 K, 2G for FCL Our goal is to completely replace 1G in 2-3 yrs. Only 2G in the upcoming SPI projects! 26 DOE Peer Review 2 *not specifically stated in FY 5 presentation
Outline Long length scale up & high-throughput manufacturing of IBAD-MOCVD conductor 2G conductor delivery for the Albany Cable Project Higher critical currents in MOCVD conductors Properties of SuperPower s 2G conductor, New 2G Prototypes Quality Control for Manufacturing Scale-up & Research Integration FY6 Performance & Results & FY7 Plans V. Selva V. Selva V. Selva Yi-Yuan Xie Jodi Reeves Jodi Reeves 26 DOE Peer Review 3
Long Length Scale-up & High- Throughput Manufacturing HTS Solutions for a New Dimension in Power Superconductivity for Electric Systems 26 Annual DOE Peer Review
In FY5, MOCVD process was scaled up to 2 m lengths Critical current (A/cm) 2 2 1 2 A/cm over 71 m Effective MOCVD speed = 5 m/h 1 11 21 31 41 51 61 71 81 91 11 111 121 131 141 151 161 171 181 191 21 Minimum Ic of 16 A/cm over 26 m (22,3 A-m) Standard deviation of 4.3% over the first 71 m with a Ic of 2 A/cm Standard deviation of 4.3% over the last m 26 DOE Peer Review 5 Position (m)
Reviewers made it very clear that the non-uniformity issue beyond 7 m in long MOCVD tapes needed top priority Comments from reviewers from FY5 Peer Review : Critical current (A/cm) 2 I found the induction period and degradation of film properties after a period of time disconcerting.i 2 think a high priority should be placed on why the process degrades after a period of time. 1 the long-length stable processing needs to be solved with high priority. Although this was a characteristic of the system being operated, it sounds like a problem that is solvable, and bodes well for a rather high critical current over much longer lengths. The process seems capable of producing coated conductors at a high rate, although there are problems at the moment in coating long lengths with uniform properties. If the process drift problems can be solved, it should be successful at meeting DOE targets for the 2G wire program 1 11 21 31 41 51 61 71 81 91 11 111 121 131 141 151 161 171 181 191 21 In FY 5: 2 passes at 1 m/h: effective speed is 5 m/h. Ic is uniform over the 1 st 71 m ~ 8 hours of processing If speed can be increased to ~ 3 m/h, then 24 m can be produced in 8 hours. Our first plan of attack was to increase speed from 5 m/h to 3 m/h 26 DOE Peer Review 6 Position (m)
Tape speed needed to be substantially increased for 2G to be commercially viable Critical current (A/cm) 3 2 2 1 Data as of April 26 ISTEC-SRL IBAD GZO & PLD YBCO SuperPower IBAD YSZ & MOCVD YBCO 1 2 2 2G Length (m) All 2+m long demonstrations last year used low speeds in buffer & YBCO processes Speed of IBAD YSZ & IBAD GZO processes ~ 1 m/h of 1 or 12 mm wide tape Effective linear tape speed of PLD processes ~ 3 m/h of 1 mm wide tape Effective linear tape speed of MOCVD process = 5 m/h of 12 mm wide tape At 5 m/h of 12 mm wide tape, annual production would be less than km/year of 4 mm wide conductor. This is far less than the current 1G market of ~ 7 km/year. 26 DOE Peer Review 7 Fujikura IBAD GZO & PLD YBCO Ic (A) Length (m) In addition to Ic & Length, high linear tape speed has to be demonstrated in YBCO processes Tape speed (m/h)
Objective set to extend helix tape handling system to all processes to enable long piece lengths & high throughput Since we use in-situ processes, we have a choice between processing a wide tape or a narrow tape with helix tape handling We chose helix tape handling because of the immense advantages it provides and the demonstrated benefits of a multi-pass process. 7 cm wide 7 cm wide Comp3.mov Much longer (> 5 times) single piece lengths - important for wire customers who are already used to several m to m of 1G Much shorter (> 5 times) process times for the same piece length Less concern with uniformity across width (5 times narrower) 26 DOE Peer Review 8
In FY6 Pilot Production Equipment was upgraded for high throughput processing of all layers IBAD Buffer MOCVD n/a FY 5 status Helix tape handling YSZ: 1 m/h Single tape; 5 m/h FY 6 plan Transition to IBAD MgO in Pilot IBAD. Modify hardware accordingly. New Pilot Buffer system with helix tape handling Retrofit with helix tape handling; Increase deposition zone length & width 2μm Cu μm Hastelloy substrate 2μm Cu 2 μm Ag 1 μm HTS ~ 3 nm LMO ~ 3 nm Homo-epi MgO ~ 1 nm IBAD MgO Tremendous challenge to successfully implement modifications in three critical pieces of equipment simultaneously & then routinely produce 1, m of conductor for delivery to Albany Cable project 26 DOE Peer Review 9
High throughput IBAD MgO has been transitioned to Pilot IBAD system Pilot IBAD system: Helix tape handling with a deposition zone length of 6 cm, 6 tape wraps. With IBAD YSZ, yielded ~ 1 m/h. With IBAD MgO would enable linear tape speeds > m/h (or a throughput > 3 m/h of 4 mm wide tape) 7 cm wide 6 cm long Up to 57 m long IBAD MgO tapes have been produced with a deposition zone of 42 cm & a speed of 65 m/h of 12 mm wide tape i.e. 195 m/h of 4 mm wide tape 26 DOE Peer Review 1
Up to 57 m long single-piece IBAD MgO tapes routinely processed in Pilot IBAD with good & uniform texture Uniform RHEED patterns obtained over process lengths up to 8 m 26 DOE Peer Review 11
Pilot Buffer System established for long length, high throughput buffer layers for IBAD MgO Two chambers for sequential deposition of 2 buffers (homo-epi MgO & LMO) on IBAD MgO Helix tape handling in both chambers, each with 12 tape wraps. Deposition zone length in each chamber =.3 m Spool boxes for 1 km single-piece lengths 2μm Cu 2μm Cu Ag μm Hastelloy substrate HTS LMO Homo-epi MgO IBAD MgO 26 DOE Peer Review 12
5 m long tapes have been produced in Pilot Buffer system at linear speeds of 4 m/h Using only 6 of the 12 tape tracks in helix tape handling in Pilot Buffer system, 4 m/h tape speed is routinely used to produce up to 5 m lengths of homo-epi MgO and LMO on IBAD MgO. In-plane texture (degrees) 1 9 8 7 6 5 4 3 2 1 142 m ; average = 7.2 225 m ; average = 7.12 332 m ; average = 6.83 438 m ; average = 6.99 543 m ; average = 7.41 1 2 2 3 3 4 4 5 6 Tape Length (m) In-plane texture of LMO over 5 m produced at 4 m/h = 7.4º 26 DOE Peer Review 13
6-fold increase in linear tape speed demonstrated with MOCVD Helix tape handling with 6 tape tracks was added to our Pilot MOCVD system for higher line speeds. Tapes processed with helix in a single pass at 3 m/h. Film thickness (micron) 1.2 1..8.6.4.2. IBAD YSZ IBAD MgO 1 2 3 4 5 6 Pilot MOCVD Critical current (A/cm) 2 2 1 Tape Track IBAD YSZ IBAD MgO 1 2 3 4 5 6 Ic ~ 2 A/cm achieved in 1.1 micron thick film at 3 m/h (single pass) by MOCVD on IBAD MgO buffers 26 DOE Peer Review 14 Tape Track
Began MOCVD processing + m lengths at 3 m/h on IBAD MgO tapes: Déjà vu all over again! YBCO film thickness YBCO composition Critical current (A/cm) 2 2 1 4.93 μm Y+Sm 1.15 Ba 1.7 Cu 3.15 16 28 Film thickness & composition are not the reason for the drop in Ic after ~ m Precursor stability is not the reason for the drop either 4 52 64 Precursor Stability Parameter 26 DOE Peer Review 15 7 6 4 3 2 76 Position (m) 1 Tape length including leader (m) 88 112 124 136.98 μm Y+Sm 1.11 Ba 1.82 Cu 3.7
Next, checked whether non uniformity in IBAD MgO or buffer quality could be reasons for the drop in Ic after m Critical current (A) 3 2 2 1 Finish 1 m end of 5 m IBAD MgO Start 1 m end of 5 m IBAD MgO 1 m 1 m 12 m 1 m 12 m IBAD MgO cut into 12, 1 m segments & spliced together with 1 m spacers to form a 12 m tape which was processed in LMO 2 3 4 Position (cm) Location in LMO run Critical current (A/cm) 1 m 2 m 3 m 4 m m 6 m 7 m 8 m 9 m m 11 m 12 m 3 2 2 1 2 4 6 8 1 12 14 16 18 2 22 24 26 28 Position in MOCVD run (m) 26 DOE Peer Review 16 12 segments of 1 m LMO were then cut out and spliced together with 1 m spacers to form a 24 m long tape & processed in MOCVD No uniformity problems with long IBAD MgO tapes No uniformity problem with homo-epi MgO + LMO buffers So, drop in Ic after m should be an MOCVD problem!
Statistics from a series of 12 MOCVD runs provided a clear reason for the drop in Ic after ~ m Intensity (arb. units) 12 8 6 4 2 (6) Start end of long tape Finish end of long tape (2) 45.5 46 46.5 47 47.5 48 48.5 2 theta (degrees) Tape length (m) 16 14 12 8 6 4 2 Total Length Uniform Ic length Critical Current (A/cm) 3 2 2 1.5 1 1.5 YBCO (2)/(6) ratio 1 2 3 4 5 6 7 8 9 1 11 12 MOCVD Run Significantly higher (2)/(6) ratio at the end of long tape. In a series of 12 MOCVD runs in lengths of to 1 m, only the first m on an average showed uniform Ic XRD analysis on samples cut from the beginning and end of the long tapes showed a good correlation between the Ic and ratio of (2)/(6) peak intensities 26 DOE Peer Review 17
Modification of MOCVD process based on XRD data yielded uniform Ic over m YBCO thickness 3 Minimum Ic of 172 A/cm over 118 m..93 μm 2 Uniformity of 6.2%.98 μm composition Y+Sm 1.16 Ba 1.72 Cu 3.13 Critical current (A/cm) 2 1 Y+Sm 1.15 Ba 1.8 Cu 3.5 Intensity (arb. units) 12 8 6 4 2 1 (6) (2) 45.5 46 46.5 47 47.5 2 theta (degrees) 17 33 49 65 Position (m) 81 Similar (2)/(6) ratio, thickness & composition at 2 ends of long tape Intensity (arb. units) 14 12 8 6 4 2 97 113 (6) (2) 45.5 46 46.5 47 47.5 2 theta (degrees) 26 DOE Peer Review 18
Intensity (arb. units) Problem with drop in Ic recurred when MOCVD production length exceeded m 3 YBCO thickness Uniformly high Ic (~ 2 A/cm) over the first m 1. μm & then Ic slow drops to ~ 1 A/cm over 391 m 1.2 μm composition Y+Sm 1.22 Ba 1.6 Cu 3.18 18 16 14 12 8 6 4 2 (6) Critical current (A/cm) 2 2 1 1 31 tape center tape front edge tape back edge (2) 45.5 46 46.5 47 47.5 2 theta (degrees) 61 91 121 151 26 DOE Peer Review 19 181 211 Position (m) 241 No significant differences in film thickness or composition at the 2 ends But, substantially higher (2)/(6) peak ratio at finish end Intensity (arb. units) 271 6 4 3 2 1 31 331 (6) 361 391 Y+Sm 1.18 Ba 1.78 Cu 3.4 tape center tape front edge tape back edge (2) 45.5 46 46.5 47 47.5 2 theta (degrees)
Retuning of MOCVD process based on XRD data yielded high Ic over 3 m with excellent uniformity YBCO thickness Critical current (A) 3 3 2 2 1 Min Ic = 263 A = 219 A/cm over 322 m. Uniformity of 4.3% over 322 m. 1.2 μm 1.2 μm composition Y+Sm 1.21 Ba 1.64 Cu 3.14 1 2 2 3 26 DOE Peer Review 2 World Record: 7,52 A-m! 77 K, Ic measured every meter over entire tape width of 12 mm Position (m) Y+Sm 1.19 Ba 1.77 Cu 3.4
Significant progress in MOCVD scale-up in the last 4 years 8, 7, 6,, 4, 3, 2, 1, Critical Current * Length (A-m) 1 m 1 m to 322 m in 4 years 18 m 322 m 26 m 158 m 97 m 62 m, 1, 1, 1 Jun-2 Dec-2 Jun-3 Dec-3 Jun-4 Dec-4 Jun-5 Dec-5 Jun-6 May-2 Oct-2 Mar-3 Aug-3 Jan-4 Jun-4 Nov-4 Apr-5 Sep-5 Feb-6 Jul-6 Nov-6 Critical Current * Length (A-m) Year 26 DOE Peer Review 21
2G conductor is now available in long lengths with Ic in the realm of 1G & Je about 2x better than 1G End-to-end critical current of 4 mm wide 2G conductor slit from 12 mm wide tape 14 End-to-end Ic = A over 27 m @.4 μv/cm 12 Critical current (A) 8 6 4 2 Position (m) Ic = A in a 4 mm wide 2G conductor over 27 m! Je = 26.3 ka/cm 2 (for a 2 micron surround stabilizer i.e. 4 micron total) compared to a 1G Je of 13 ka/cm 2 to 17 ka/cm 2 26 DOE Peer Review 22 1 21 41 61 81 11 121 141 161 181 21 221 241 261