Download Long Length Characterization of CC Tapes

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
ƒ
ƒ
ƒ
„
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