2G HTS Wires for High Magnetic
Fi ld A
Field
Applications
li ti
Venkat Selvamanickam
Department of Mechanical Engineering
Texas Center for Superconductivity
U i
University
it off Houston,
H
t
Houston,
H
t
TX,
TX USA
SuperPower Inc, Schenectady, NY, USA
1
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 Æ very
different from mechanical deformation & heat treatment techniques used for
Nb Ti Nb3Sn and 1G HTS wires
Nb-Ti,
–
–
–
–
Only 1% of wire is the superconductor
~ 97% is inexpensive Ni alloy and Cu
Automated reel-to-reel continuous manufacturing process
Automated,
Quality of every single thin film coating can be monitored on-line
in real time !
40 μm Cu total
2 μm Ag
1 μm YBCO - HTS (epitaxial)
100 – 200 nm Buffer
20μm Cu
20μm Cu
50μm Ni alloy substrate
2G HTS wires provide unique advantages
YBCO (H//c)
YBCO (H//ab)
Nb3Sn (Internal Sn)
Nb3Sn (Bronze)
< 0.1 mm
m
• 2G HTS wires provide the advantages of high temperature operation at higher
magnetic fields.
• Mechanical properties of 2G HTS wires are also
20μm Cu
superior
NbTi
50μm Hastelloy
20 m Cu
20μm
800
2
non-Cu Jc ( A/m
mm )
100000
10000
SP 2G HTS
High Je
600
100
0
5
10
15
20
25
Applied Field ( Tesla )
30
35
Stress (M
MPa)
1000
400
High Strength
1G HTS Low Je
200
Nb3Sn
Moderate Je
Low Strength
1G HTSModerate Je
0
0
0.1
0.2
0.3
Strain (% )
0.4
0.5
3
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
L
process runs ((already
l d shown
h
50
50+ h
hours))
< 0.1 mm
20μm Cu
2 μm Ag
1 μm YBCO - HTS (epitaxial)
~ 30 nm LMO ((epitaxial)
p
)
~ 30 nm Homo-epi MgO (epitaxial)
YBCO
~ 10 nm IBAD MgO
100 nm
LaMnO3
50μm Hastelloy substrate
20μm Cu
MgO (IBAD + Epi layer)
Y2O3
Al2O3
Hastelloy C-276
4
300
200
100
0
0 100 200 300 400 500 600 700 800 9001000
Position (m)
320,000
1,065 m
280,000
90 A-m to
300,330 A-m
in seven
years
240,000
200,000
1,030 m
935 m
160 000
160,000
790 m
120,000
May-09
Sep-08
Jan-08
Apr-07
Aug-06
Dec-05
Apr-05
Aug-04
Nov-03
0
Mar-03
40,000
427 m
322 m
206 m
1 m 18 m 97 m
158 m
62 m
Jul-02
80,000
595 m
Nov-01
*4 mm wide equivalent
400
Critical Curre
ent * Length (A--m)
• 500 m 2G HTS wire first
demonstrated in January 2007
(crossed 100,000 A-m)
• 1,000 m 2G HTS wire first
demonstrated in July 2008
(
(crossed
d 200
200,000
000 A
A-m))
• Crossed 300,000 A-m in July
2009 with 1,000 m wire.
• 1,400
1 400 m llengths
th are now
routinely produced.
• High throughput processing (>>
100 m/h*
m/h in IBAD & buffer
processes, > 100 m/h* in other
processes)
• Manufacturing capacity of few
hundred km/year
Critical Curren
C
nt (A/cm)
Successful scale up of IBAD-MOCVD based 2G
500
HTS wires
i
5
Meeting application requirements for HTS wire:
Superior performance in operating conditions
Application
Operating
Field (Tesla)
Operating
Temp. (K)
Key requirements
Wire needed per
device (kA-m)
0.01
0
01 tto 0
0.1
1 ((ac))
0.1 to 1 (DC)
70 to 77
Low ac losses
L
l
((ac))
High currents (dc)
40,000
40
000 tto
2,500,000
1 to 3
30 to 65
In-field Ic
2,000 to 10,000
Transformers
0.1
65 to 77
Low ac losses
2,000 to 3,000
Fault current
limiters
0.1
65 to 77
Thermal recovery
High volts/cm
500 to 10,000
2 to 30 T
4 to 50
In-field Ic
2,000 to 3,000
Automotive
motors
2 to 5
30 to 65
Low ac losses
In-field Ic
500 to 1,000
Aerospace
2 to 5
30 to 50
Light weight
In-field Ic
1,000 to 2,000
Magnets/coils
5 to 30
4 2 to 40
4.2
In-field
In
field Ic
200 to 2
2,000
000
4.2 K to 30
In-field Ic
Long lengths
Persistent joints
2000 - 100,000+
Cables
Wind/Off-shore
Generators
SMES
MRI, NMR, HEP,
Fusion reactors
5 to 30
6
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 deliveryy of highg
quality wire
• Incorporate new technology
advancements
Manufacturing
Operations in NY
SuperPower
Manufacturing at
Schenectady, NY
Technology
in Houston
SP staff @
Houston
UH research
staff
Technology objectives
• High performance wires
• Highly efficient, lower cost
processes
• Advanced wire architectures
• Successful transition to
manufacturing
CRADAs
Customers
National Labs
Best of both worlds : strong and concentrated emphasis on
technology development & manufacturing
Improved
p
p
pinning
g by
y Zr doping
p g of
MOCVD HTS wires
5 nm sized, few hundred nanometer long BZO nanocolumns with
~ 35 nm spacing created during in situ MOCVD process
Improved pinning by Zr doping of MOCVD
HTS wires
i
• Systematic study of improved pinning by Zr addition in MOCVD films at UH.
• Two-fold improvement
p
in in-field p
performance achieved !
5%
12.50%
70
1.6
1.4
60
1.2
50
1.0
40
0.8
30
0.6
20
0.4
10
1.0 T, 77 K
0.2
40
Critical ccurrent (A/4 m
mm)
2.5%
10%
Jc (MA//cm2)
Crtiical curren
nt (A/12 mm)
80
0%
7.50%
Standard Production wire
Enhanced Zr‐doped production wire
30
c‐axis
20
10
0 30 60 90 120 150 180 210 240
Angle between field and c‐axis (°)
‐30 0 30 60 90 120 150 180 210 240 270 300 330 360
Angle between field & tape normal (°)
Process for improved in-field performance successfully transferred to
manufacturing at SuperPower
9
Benefit of Zr-doped wires realized in
coil performance
C il properties
Coil
ti
With Zr‐doped
Z d
d wire
i
With undoped
d
d wire
i
Coil ID
21 mm (clear)
12.7 mm (clear)
Winding ID
28 6 mm
28.6
19 1 mm
19.
# turns
2688
3696
2G wire used
~ 480 m
~ 600 m
Wire Ic
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
p wire with less zero-field 77 K
achieved with Zr-doped
Ic, less wire and larger bore
10
Large improvements in in-field Ic of
Z d
Zr-doped
d wires
i
att llower ttemperatures
t
ttoo
Critical current (A
A/cm)
10000
18 K
40 K
65 K
B ⊥ tape
18 K undoped
40 K undoped
65 K undoped
1000
100 A/4 mm
100
All data from
production
wires
10
0
1
2
3
4
5
6
g
Field (T)
( )
Magnetic
7
8
9
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
Large improvements in in-field Ic of
Z d
Zr-doped
d wires
i
att llower ttemperatures
t
ttoo
Jc (B, T) / Jc (7
77 K, 0 field
d)
10.00
40 K undoped
Retention of
77 K, zero field Ic
65 K
3T
40 K
3T
18 K
3T
65 K undoped
Undoped wire
0.27
1.02
2.13
D
Doped
d wire
i
0 73
0.73
1 99
1.99
3 50
3.50
Retention factor of
doped wire is higher by
2.7
1.9
1.6
18 K
18 K undoped
40 K
65 K
1 00
1.00
77 K zero-field Ic of 2009 undoped wire = 250 A/cm
77 K zero-field Ic of new doped wire = 340 A/cm
B ⊥ tape
0.10
0
1
2
3
4
5
6
Magnetic Field (T)
7
8
9
Retention factor of
doped wire including
higher zero field Ic is
higher by
3.71
2.64
2.23
12
Superior performance in recent Zr-doped
MOCVD production wires in high fields at 4
4.2K
2K
60
Production wire
1.1 µ
µm thick HTS film
Ic (77 K, 0 T) = 310 A/cm
50
1000
Ic - 4mm w
width (A)
Jc, MA/cm2
40
T=4.2K
30
20
10
0
0
20
40
60
80
T, K
Jc @ 4.2 K (A/4 mm)
2009
2010
10 T,
T B ⊥ wire
201
310
20 T, B ⊥ wire
118
183
5 T, B || wire
1,219
1,893
10 T, B || wire
1,073
1,769
100
undoped, B perp. wire
undoped, B || wire
FY'09 Zr-doped,
p ,Bp
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
High-Field Magnets demonstrated with
2G HTS wire
• Coils fabricated
by SuperPower
and NHMFL
• Je ~ 300 A/mm2
• Stress levels 300
– 400 MPa
14
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
Goals for further performance improvements
• T
Two-fold
f ld iimprovementt iin iin-field
fi ld performance
f
achieved
hi
d with
ith Zr-doped
Z d
d wires
i
• Further improvement in Ic at B || c : Now 30% retention of 77 K, zero field value at
77 K, 1 T ; Goal is 50%.
• Improvement
I
t in
i minimum
i i
Ic Æ controlling
t lli ffactor
t ffor mostt coilil performance
f
:N
Now 15 tto
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 Ic of 400 A/4 mm at 77 K, self field Æ 200 A/4 mm at
77 K
K, 1 T in all field orientations
orientations.
• Achieve improved performance levels at lower temperatures too (< 65 K)
G l
Goal
Critical cu
urrent (A/cmwidth)
w
1000
800
600
400
200
0
0
1
2
3
Thickness (µm)
Critical currrent (A/4 mm
m)
200
Standard MOCVD‐based
MOCVD based HTS tape
MOCVD HTS w/ self‐assembled nanostructures
100
Goal
10x
77 K, 1 T
c‐axis
10
0
30
60
90
120
150
180
210
240
Angle between field and c‐axis (°)
16
Multiple strategies to enhance in-field
performance : higher Ic, more isotropic
• Superconductor process modification
– Chemical modifications in MOCVD to
modify defect density, orientation and
size.
• Influence of film thickness on in-field
Ic 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.
17
1
Opportunities with rare-earth
modifications:
difi ti
IInfluence
fl
off Y+Gd content
t t
7.5% Zr in all samples
Y content = Gd content
Y+Gd content varied
130
330
110
310
290
90
270
250
70
1.2 1.3 1.4 1.5 1.6
Y + Gd content
Criticaal current (A
A/12 mm)
eld Ic (A/12 m
mm)
zero‐fie
350
Y0.65Gd0.65
Ic at 1 T, || to tape (A/12
2 mm)
•
•
•
Y0.7Gd0.7
Y0.75Gd0.75
Y0.8Gd0.8
110
90
70
50
30
1.0 T, 77 K
10
60
90
120
150
180
210
240
270
Angle between magnetic field and c‐axis (°)
300
Critical current can be tuned in desired orientation of magnetic
g
field in
application by modifying total rare earth content even with a fixed Zr % !
18
Increased nanoscale (Gd,Y)2O3 precipitates
along a-b plane with increased rare earth content
(Gd,Y) = 1.2
(Gd Y) = 1
(Gd,Y)
1.3
3
(Gd,Y) = 1.4
(Gd,Y) = 1.5
19
Thicker (Gd,Y)2O3 precipitates along
a-b plane in high (Gd,Y) wires
(Y,Gd)1.2
(Y,Gd)1.3
(Y,Gd)1.4
Ic / Ic (B=0)
0.4
(Y,Gd)1.5
1.0 T, 77 K
0.3
0.2
0.
0.1
70
75
80
85
90
95
100
105
Angle beteweend field and c‐axis (°)
TEM by Dean Miller, ANL
20
In-field performance of Zr-doped films is
d ti ll modified
drastically
difi d b
by rare earth
th content
t t
Zr content maintained at 7.5% in all three samples
Y0.6Gd0.6
(Y,Gd)1.5
Crittical curren
nt (A/12 mm)
140
Y1.2
Y1.2
1.0 T, 77 K
120
100
80
(Y,Gd)1.5
c‐axis
60
40
20
60
90
120
150
180
210
240
270
300
Angle between field and c‐axis (°)
20 nm
Multiple controls available to modify pinning performance of 2G HTS wires!
21
Higher amperage wires using thicker films
7
Jc (MA//cm2)
6
5
Goal
4
3
2
0
1
2
3
Thickness (µm)
Goal
Critical curre
C
ent (A/cmwidth
h)
1000
800
600
400
200
0
0
1
2
3
Thickness (µm)
• 800 A/cm (=
( 320 A/4mm) already
alread
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
Higher amperage wires using thicker films
8
Jc (MA/cm 2)
6
Increasing Ic
5
2016 – 1000 A
4
3
2014 – 750 A/cm
2012 – 500 A/cm
2
1
0
0
0.5
1
1.5
2
HTS film thickness
SP
M3
714
2.5
3
3.5
Critical currrent (A/cmwidth)
7
Goal
1000
Research MOCVD
Pilot MOCVD
800
600
400
200
0
0
1
2
3
Thickness (µm)
• Address problems with decreasing
current density with thickness
• High currents without significantly
increasing film thickness by increasing
current density (Jc)
– Mi
Microstructural
t t l improvement
i
t (t
(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
Another benefit with thicker films: better
in field performance
in-field
Criticcal current (A//12 mm)
170
7.5% Zr, 1 pass
1.0 T, 77 K
120
70
20
60 90 120 150 180 210 240 270 300
Angle
g between field and c‐axis ((°))
180
160
140
120
100
80
60
40
20
0% Zr, 2 passes
0% Zr, 3 passes
Critical currrent (A/12 mm
m)
Critical ccurrent (A/12 mm)
0% Zr, 1 pass
180
160
140
120
100
80
60
40
20
7.5% Zr, 3 passes
1.0 T, 77 K
7.5% Zr, 2 passes
60 90 120 150 180 210 240 270 300
1.0 T, 77 K
Angle between field and c‐axis (°)
All samples were of composition
Y0.6Gd0.6BCO
Improvement in in-field critical
current of Zr-doped
Zr doped wires
increases with film thickness
60 90 120 150 180 210 240 270 300
Angle between field and c‐axis (°)
24
Can high-field
high field performance be improved with
higher Zr doping levels?
400
Tc
300
93.0
92.0
250
200
91.0
150
90.0
100
89.0
50
0
0%
5%
10%
15%
20%
88.0
25%
2.0
Ic
350
ΔTc
300
1.5
250
200
1.0
150
100
ΔTc (K
K)
Ic
350
Critica
al current ((A/12 mm)
94.0
Tc (K
K)
Critica
al current ((A/12 mm)
400
0.5
50
0
0%
5%
Zr content (%)
0.0
10% 15% 20% 25%
Zr content (%)
• Zero-field critical current drops beyond 7.5% Zr addition.
• Sharper drop in Tc beyond 10% Zr addition (3 K from 10% to 25%)
• Transition width increases by 0.5 K beyond 15%
25
In-field Performance at higher Zr doping levels
2009
0.4 µm film, Y0.65Gd0.65BCO
80
350
70
200
60
150
50
40
100
30
zero field
B || ab, 1 T
B || c, 1 T
50
20
10
0
5%
10%
Zr addition
100
300
80
250
200
60
150
40
100
zero field
50
0
0%
120
15%
B || ab, 1 T
20
In-fie
eld Ic (A/12 mm)
400
zero fie
eld Ic (A/12 mm)
90
In-fie
eld Ic (A/12
2 mm)
Zerof field Ic (A/12 mm)
250
2010
0.9
0 µm film, Y0.6Gd0.6BCO
O
B || c, 1 T
0
0%
5%
10%
0
15%
Zr addition(%)
• Best performance at B || c with 7
7.5%
5% Zr.
Zr
• Ic at B || a-b increases at higher Zr content even with lower zero-field Ic
• Opportunities with high Zr doping levels in B || a-b
26
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
6000
77 K, 0 T
4.2 K, 15 T
20 K, 10 T
30 K, 5 T
50 K
K, 5 T
65 K, 3 T
2000
1500
1000
5000
4000
3000
2000
500
E
Engineerin
ng current
density, Je
d
e (A/mm2)
Critic
cal current (A/4mm)
Targeted improvements in in-field performance
of production wires through technology
1000
0
0
Now
2016
• 10-fold improvement by combination of higher self-field critical current and
p
retention of in-field p
performance through
g technical innovations.
improved
• Even at 4.2 K, 15 T, 2G HTS wire is comparable now with Nb3Sn wire.
Opportunity to improve to be 10X better than Nb3Sn !
28
Multfilamentary 2G HTS tapes for low ac loss
applications
2
• So far, there is no proven technique to
repeatedly create high quality mulfilamentary
2G tapes.
tapes Also,
Also adds substantial cost
cost.
ac loss (W/m)
• Filamentization of 2G HTS tapes is desired
for low ac loss applications
applications.
unstriated
100 Hz
1
5.1 x
multifilamentary
0
0.00
0.01
0.02
0.03
0.04
0.05
0.06
Bac 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
Goals in multifilamentaryy 2G HTS wire fabrication
• Maintaining filament integrity uniform over long lengths (no Ic reduction)
pp stabilizer ((minimize coupling
p g losses))
• Striated silver and copper
• Minimum reduction in non superconducting volume (narrow gap) and
fine filaments
HTS
Ag
Substrate
Cu
A fully filamentized 2G HTS wire would need to have 20 – 50 µm of copper
stabilizer striated !
30
Approach
pp
to make fully-filamentized
y
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 7,627,356
31
3
Etch-free p
process developed
p to fabricated
multifilamentary wire with fully striated stabilizers
12-filament wire with 10 µm thick
fully striated copper stabilizer
32
Significant ac loss reduction in multifilamentary
wire with fully striated stabilizers
1.E+01
• Critical current of standard
wire = 207 A
• Critical current of 12filament wire after 10 µm
copper stabilizer = 200 A
AC loss of 12-fiament wire at
60 H
Hz is 11 times lower
lo er than
that of unstriated wire without
copper stabilizer and 13 times
lower with copper stabilizer, at
higher fields
1.E+00
ac loss (W
W/m)
• Critical current of 12filament wire = 197 A
60 Hz
1.E-01
1.E-02
Multfilamentary
1.E-03
Standard
1.E-04
Multifilamentary + Cu
Standard + Cu
1.E-05
0.001
0.010
0.100
ac magnetic field (T)
33
Significant
g
ac loss reduction in multifilamentaryy
wire with fully striated stabilizers
16
300 Hz
1.E+00
1.E-01
0
Multifilamentary
1.E-02
1.E-03
Standard
Multifilamentary + Cu
Standard + Cu
0.010
12
10
0
Multfilamentary
8
Standard
Multfilamentary + Cu
6
Standard + Cu
4
2
1.E-04
0.001
0.02 T
14
ac loss (W
W/m)
ac loss (W/m)
1 E+01
1.E+01
0.100
ac magnetic
ti fi
field
ld (T)
0
0
100
200
300
400
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
Keyy 2G HTS wire metrics attractive for high
g
magnetic field applications
• Piece lengths:
– 1,000 m demonstrated with minimum Ic of ~ 300 A/cm
– 1,400 m routinely processed
– 100 – 300 m typical
yp
• Critical current in production wires
– 325 A/cm available in long lengths (100 – 300 m)
– 810 A/cm (Je = 810 A/mm2) at 4
4.2
2K
K,10
10 T
T, field perpendicular to wire
– 480 A/cm (Je = 480 A/mm2) at 4.2 K, 20 T, field perpendicular to wire
– 1855 A/cm (Je = 1855 A/mm2) 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
fields.
– Goal of Je = 6000 A/mm2 at 4.2 K, 15 T perpendicular to wire (~ 10x Nb3Sn
performance); 1000 A/mm2 at 40 K, 15 T perpendicular to wire
35
Keyy 2G HTS wire metrics attractive for high
g
magnetic field applications
• Superior
p
mechanical p
properties
p
– Yield strength > 700 MPa with superalloy-based 2G HTS wire
– Tensile and bend strains > 0.4% without performance degradation
– Intense
I t
R&D to
t improve
i
transverse
t
stress
t
properties
ti
• Joints
– Joint resistance of 50 – 100 nano-ohm cm2 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
ltfil
t
wires
i
36