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Long Length Characterization of CC Tapes J. Yates Coulter, Jeffrey O. Willis, Jens Hänisch, and Leonardo Civale Los Alamos National Laboratory FY08 Budget: $275 K Project Goal: To provide nondestructive critical current characterization of long coated conductors for process feedback and for quality assurance Approach and Project Management: We develop methods, hardware, & software (i.e., IP) at LANL. We can then use our facilities to measure tapes from any industrial partner. Measurement results are part of the respective CRADA project. IP is transferred to industrial partners as appropriate. Relevance: The project directly supports the goals of DOE-OE to develop HTS technologies to modernize the electric grid. Slide 1 Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA Background of the project: Ic(x, B) base system Started in response to measurement needs for in-house coated conductor (CC) scale-up programs in 1999-2005 Nondestructive critical current (Ic) characterization as a function of position (Ic(x)) for tapes 1-10 m long Feed Reel Take up Reel Tape V H tape Magnets Conductive Roller, I+ measurement stage magnetic field Conductive Roller, I- In-field measurements: reduced Ic avoids sample damage and defines the position B||c up to ~0.75 T, 1 cm wide tape, 80 A max, 1 I-V curve per minute System easily modified to new configurations Slide 2 Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA Two field orientation Ic data is used to analyze variations in a long length CC Experimental method 45 Ic [A] 40 35 30 • • • H||ab H||c 25 0.8 R(x) 20 1.0 0 100 200 300 400 Position x [cm] T=75.5K H=0.53T 500 600 2 different field strengths 2 different field orientations 2 different temperatures Analyze: take the ratio R(x)= Ic1(x)/Ic2(x) R(x) ≈ const. ⇒ variations only due to A(x) R(x) ≠ const. ⇒ variations due to structural/compositional fluctuations 4mm wide stabilized 2G wire (LANL 172) 0.6 Measure Ic(x)=Jc(x)*A(x) [A(x) is cross section area] under two conditions, for example: Example: R(x) determined from Ic at two angles: not constant, therefore structural/compositional fluctuation Results confirmed by TEM (Presented at FY07 Peer Review, LANL-AMSC CRADA talk) Slide 3 Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA In FY06 a key technology, the magnet rotator stage, was designed, built, and installed on the base system • • Determine Ic(x, Bo, B||c) and Ic(x,Bo,B||ab) on the complete tape length Rewind to measure Ic(x, Bo, θ) at selected values of x 50 where there are features of interest 45 Drive shaft 40 (PR07 LANL-SuperPower CRADA result) 50 45 Critical Current (A) We can now obtain the full angular anisotropy to better understand the nature of the behavior observed in the bi-axial data Measurement protocol: Critical Current (A) 35 Position(cm) 40 35 0 540 575 625 635 700 B||ab B||c 30 25 20 0 100 200 300 400 500 600 700 Position x (cm) 30 25 T=75.5K, B=0.52T 20 -30 TEM 0 30 60 90 120 150 Angle (degrees) Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA Slide 4 FY08: Electromagnet measurement stage added to system Electromagnet stage allows Ic(x, B, B||c), for B to ~1.5 T Electromagnet Magnet Rotator Flat-topped magnetic field profile Voltage tap Current lead pulley Guide pulley Magnetic Field (T) 0.5 0.4 0.3 0.2 0.1 0.0 0 2 4 6 Position x (cm) Slide 5 Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA 8 FY08: Electromagnets do need some modifications before use in Ic measurements As received Remove local flux return path 0.5 N S N S N S Magnetic Field (T) Tape path 0.6 0.4 0.3 As received electromagnet 0.2 0.1 0.0 -0.1 -8 -6 -4 -2 0 2 4 6 8 Position x (arb units) 0.6 Tape path N S N S S N + add external yoke flux return path 0.5 Magnetic Field (T) Modified 0.4 Modified electromagnet 0.3 0.2 0.1 0.0 -0.1 -8 -6 -4 -2 0 2 4 6 8 Position(arb units) Slide 6 Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA FY08: We can now measure Ic(H||c) and perform an α analysis on a long coated conductor 45 90 H||c 35 30 20 H||ab H||c T=75.5K H=0.53T 0 20 40 60 80 100 Position x [cm] Ic [A] 30 H||c single coat YDy0.5BCO - 344 wire 0.1 μ0H [T] le Se 1 30 X [cm] 30 32 33 Isotropic region 42 44 46 es v r cu d cte Anisotropic Region 0.1 μ 0H [T] 1 Conclusion: α varies distinctly between 0.67 and 0.84 Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA Slide 7 X [cm] 28 30 32 33 34 36 38 40 42 44 46 140 We measured Ic(H//c) at several closely spaced positions throughout the anisotropic variation 90 60 120 [A] 25 60 Ic Ic [A] 40 Addition of a second measurement stage in FY05 to increase speed initially led to power dissipation problems Two selectable angle stages were added to the base system We could now determine Ic(x, Bo, θ=0) and Ic(x, Bo, θo) , where Bo is a fixed field, and θ is the angle at which the field is applied (θ=0° is the c axis) and θ is typically 90° (ab plane) or perhaps 45° 20 B||ab B||c Voltage (μV) 15 10 5 0 0 20 40 60 80 Current (A) Up to 3 stages could be used to measure at 3 different angles (anisotropy), at 3 fields (field dependence), or all at same angle & field (3X faster) However, excessive power dissipation (up to 8 W!!) in the H||c region led to implementation of a different magnetic field technique Slide 8 Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA FY08: Electromagnet stage also solved multi-watt heating problem during two-channel V-I measurements Region in H||ab stage reaches Ic V (μV) B (T) Dissipation is switched off by turning off electromagnet Current (A) Region in H||c stage reaches Ic 60 Sample Current 40 20 0 0.6 0.5 0.4 H||c Magnetic Field 0.3 0.2 0.1 0.0 150 Voltage H||c 100 50 0 150 100 Voltage H||ab 50 0 Current ramp started H||c (electromagnet) set to field Heating in H||c region above Ic was a big problem (sample damage): Electromagnet stage enables twoorientation data acquisition V (μV) End of current ramp 0 10 20 Time (s) Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA 30 Slide 9 FY08: Integrated electromagnet use for two-orientation data acquisition This is the new standard in our lab for Ic(x, B, θ, T) characterization Example: High strength conductor investigation Raw bi-axial data R analysis 60 55 2.0 1.9 45 40 R [Icab/Icc] Critical Current (A) 50 B||ab B||c 35 30 1.7 1.6 25 T=75.5K μH=0.52T 20 15 500 Mean ±σ 1.8 600 700 800 900 1000 500 600 700 800 900 1000 1100 Position x (cm) 1100 Position x (cm) AMSC conductor Regions for possible further investigation, e.g., Ic(θ) Slide 10 Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA FY08 Goal: Increase measurement speed to 10 m/h Three technical challenges 1) Tape handling (x) 2) Coverage: Ic(H||c) Electromagnet 3) Coverage: Ic(H||ab) Magnet Rotator Solution: we focused on demonstrating tape handling and then scaled up the magnet systems……. Slide 11 Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA FY08: Tape handling for increased speed to 12.75 m/hr Reference sample is a 10 m SuperPower tape measured with 2.5 cm step size in 5 hours (2 m/h) 70 70 H||ab H||c 50 T=75.5K μH=0.52T 40 30 H||ab H||c 60 Critical Current (A) Critical Current (A) 60 20 Remeasured tape with 15 cm step size in 0.8 hour (12.75 m/h) 50 T=75.5K μH=0.52T 40 30 Measurement Speed: 2 m/h 0 200 400 600 Position x (cm) 800 1000 20 Measurement Speed: 12.75 m/h 0 200 400 600 Position x (cm) 800 1000 Ic variations observed in previous characterizations reproduced, indicating the handling and software systems performed properly Next step: Scale up magnet systems to provide complete coverage and let CRADA partners demonstrate speed as needed Slide 12 Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA FY08: Developed new measurement stages for multiple use: Magnet rotator stages Worked with a local engineering company to • • • Made additional modifications to provide • a longer field region improved field uniformity with a high permeability yoke Field region ~10 cm, µH ~<0.7 T • • Duplicate the magnet rotator previously built in house in FY06 Optimize tolerances Standardize manufacturing FY08 Goal: Provide to SuperPower Slide 13 Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA FY08: Developed new measurement stages for multiple use: Long electromagnet stage Worked with an electromagnet manufacturer to improve the cryogenic compatibility of their hardware Developed two new designs • To measure a wide (e.g., 4 cm) tape (field vertical and across width) To measure over a longer field region (field vertical and along length) • Improved maximum magnetic field by changing magnet configuration and yoke design Magnetic fields to 1.25 T, length to ~10 cm FY08 Goal: Provide to AMSC Slide 14 Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA Summary and Milestones To design, fabricate, and install position-dependent Ic measurement systems for each of the industrial partners AMSC and SuperPower. - Measurement systems have been designed, built, calibrated, and are scheduled to ship to AMSC and SuperPower. To achieve a 5-fold increase in the speed of the Ic(x) measurement, to reach a 10 m/hour benchmark for characterization at one orientation. - Exceeded goal - demonstrated measurement speed up to 12+ m/h with reduced coverage and standard system; full coverage with new, longer magnet stages. To develop smart software for automatic identification of tape sections with problems and other features of interest. - Developed several algorithms for identification and quantification of regions of interest for Ic(x) data. To adapt the measurement system for accommodating tapes longer than 100 m. -Present capability is up to about 75 m, depending on conductor thickness, more than adequate for measurement requests to date (~25 m maximum). -Rather than scale up our capabilities to longer lengths at this time, in collaboration with our CRADA partners, we are accomplishing this goal by providing measurement systems to them for integration with their long length inhouse characterization capabilities (See collaboration goal above). Slide 15 Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA Technology Transfer As part of the technology transfer goals of this subtask we have, in consultation with two of our CRADA partners, designed, constructed and calibrated measurement systems for these industrial partners during the review period. AMSC: Short (2.5 cm) permanent magnet rotator stage and long (10 cm) electromagnet fixed axis stage SuperPower: Long (10 cm) permanent magnet rotator stage We have also measured conductors for these partners during the review period. These activities are described in the respective CRADA presentations: • • LANL/AMSC (this session, 8:00 AM this morning) LANL/SuperPower (this session, 3:30 PM this afternoon) . Slide 16 Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA Future Plans We will continue to improve the capabilities of our measurement system to handle new conductor formats (e.g., much more mechanically robust stainless steel sheathed tapes, wider format tapes) now being produced by industry. We will increase the maximum current capability of our standard measurement apparatus by a factor of 2 to 250 A to accommodate higher performance conductors. We will continue to develop advanced characterization methods, based on internal LANL goals and CRADA partner requirements, to provide more accurate, more sophisticated, and more rapid measurement results (e.g., explore shorter length feature investigation capability). We will work with commercial equipment vendors to build reliable characterization systems for LANL and for our industrial partners. Slide 17 Superconductivity for Electric Power Systems Annual Peer Review July 28-31, 2008 Arlington, VA