Transcript MgB2 wire development for low

ADVANCES IN INDUSTRIAL
PRODUCTION OF MgB2 WIRES
Giovanni Grasso
Columbus Superconductors SpA
Aknoweledgements
 S. Brisigotti, A. Tumino, S. Berta, R. Penco, D.
Pietranera, L. Rostila – Columbus Superconductors SpA
 A. Malagoli, V. Braccini, M. Vignolo, C. Ferdeghini, M.
Putti – CNR/INFM
 D. Nardelli, R. Marabotto, M. Modica, A. Pellecchia – ASG
Superconductors SpA
 A. Ballarino, L. Rossi – CERN
 A. Morandi, S. Imparato - Univ. Bologna
 N. Magnusson, M. Runde - SINTEF
 B. Coppi, F. Bombarda – MIT
 R. Musenich - INFN
Outline






Considerations on MgB2
The ex-situ manufacturing process
Main properties
Industrial production
Applications
Conclusions
Current situation
 Superconductivity is a wonderful phenomenon,
but its today’s applications are still confined to
MRI-NMR, R&D, current leads and ‘big physics’
 2G HTS material is expected to modify soon
this scenario, but its complexity and limitation
is currently delaying its positive effect on the
industrial market of superconductivity
 What can we expect more from MgB2?
Applications
 Making a good superconducting product is a
formidable interdisciplinary problem
Wire
performance
Cryogenics
Wire cost
Engineering
Look
Cables
FCL
MRI
Dedicated
MRI
MgB2
Very simple crystal structure
Polycristalline materials
carry large currents
Very high current densities
observed in films
Moderately high Tc
Good mechanical properties
1.2
Sample No. 1
Sample No. 2
2
1.0
1
0.9
3
5
0.8
0.7
8
0.5
7
4.2K(Liq. He)
4T Tape Surface
Soldered to SUS304 Rig
0.4
-0.6
-0.4
-0.2
0
Low cost – low weight
MgB2 precursors:
150 €/Kg today
6
0.6
T
Ic/Ic(Zero External Strain)
1.1
MgB2 presents
very promising
features
Factor of 10 larger than in bulks; room for large
improvement in wires still available from R&D
Potentially high critical field
60
40
bulk dirty
limit
wire SiC
doped
30
20
10
clean limit
0
4
0.2
thin film
dirty limit
50
Upper critical field Hc2 [T]
Tc of 39K
0.4
External Strain (%)
0.6
0.8
MgB2 mass density:
2.5 kg/dm3
0
5
10
15
20
25
30
35
40
Temperature [K]
Larger than 60 Tesla at low T
Superconducting wires presently
available on the market
NbTi
Nb3Sn
MgB2
Bscco
YBCO
Tc (K)
9K
18 K
39 K
108 K
90 K
Bc2 (T)
10 T
28 T
<70 T
>100 T
>100 T
Operation in LN2
NO
NO
NO
< 1T
<2T
Ductile compound
YES
NO
NO
NO
NO
Flexible wires
YES
NO
YES
YES
YES
Superconducting
splices
YES
YES
YES
NO
NO
Low cost
YES
≈YES
YES
NO
Not yet
Wire type
LTS
MTS
HTS
Considerations on MgB2
 MgB2 development makes industrial sense if:
-it can reach intermediate properties than
those of NbTi and Nb3Sn at 4.2K
-it can reach a current density of 100 A/mm2
in a field of 4-6 Tesla and temperature of
10K and above
 Both results should be compatible with low
wire cost (<10$/kA▪m) and good mechanical
properties (R&W), εcr > 1%
The ex-situ process
+
B
Mg
MgB2
Advantages:
High MgB2 packing density (>80%)
Short sintering time (100-300 s)
High εcr of 1% with Monel 400 sheath
Good control of MgB2 particle size
Sustain high annealing temp. up to 800°C
No need of Niobium sheath
Fine particle size can be used
Disadvantages:
Dedicated cold working and sintering
equipment have to be used
Sintering of MgB2 occurs at high temp.
above 850°C
MgB2 grain growth and ‘cleaning’ occurs
Fabrication of MgB2 wires by the
ex-situ P.I.T. method used
325 mesh
99% purity
+
B
amorphous
95-97% purity
tube filling
1.3 g/cm3
Mg
mixing
wire drawing to 2 mm
reaction at
900°C in Ar
MgB2
cold rolling
reaction at
900-1000°C in Ar
Fabrication of MgB2 wires by the
ex-situ P.I.T. method
advantages
 Straightforward multifilament processing
 Significant homogeneity over long lengths
 Allows careful control of the MgB2 particle size and purity
disadvantages
 Need of hard sheath materials and strong cold working
 Jc is very sensitive to the processing route
 More tricky to add doping and nanoparticles effectively
Reliable method for exploring long lengths manufacturing
Going from flat tape to round-square
wires cleans up conductor anisotropy,
and the field dependence of Ic improves
accordingly. However, the use of clean
MgB2 leads to sharp drop of jc(B)
Enhancements in the
P.I.T. ex-situ method
Possible routes:
Commercial precursors
B
Mg
MgB2
B
MgB2
Mg
Doped boron
MgB2(dope B(doped)
d)
+
Commercial
MgB2
Mg
B
+
dopant
+
Home made boron
MgB2
High
energy
ball
milling
tube filling
+
wire drawing to 2 mm
B
+
cold rolling
Mg
B2O3
reaction at
Requirements for applications
High field performance demonstrated in R&D wires by many groups
Transport Ic (A)
1000
T=4.2K
mill 144h
w/ 0.5% C
100
10
not mill
1
2
4
mill 24h
w/ 10% SiC
6
8
B (T)
10
mill 144h
12
14
Columbus Superconductors
 Has its own production
facilities in Genoa with
leading capability to
produce and supply
MgB2 wires on a
commercial basis since
two years – most used
for MRI so far






The new plant is operational for a wire production readily scalable up
to 2-3’000 Km/year if requested by the market in 3-6 months time
Wire unit length today up to 4 Km in a single piece
Total plant area 3’400 m2 – 60% of it in use today
Total production for MRI so far exceeded 400 Km of fully tested wires
MgB2 compound production now implemented into the owned area
Increased interest from customers developing power applications
Columbus wires
 Production of MgB2 wires in our
Company is expected to grow twice
each year for the next three years
 Because of the higher volumes and
optimized manufacturing
methodologies, from 2012 it is
expected that the conductor price
would have reached its final target
value within 20÷40%
Monolithic design -1 Two basic monolithic wire designs for magnet
application are currently under development and
parallel production
A)
Nickel 201
Iron 99.5%
Copper OFHC C10200
MgB2
Monel 400
Nickel 201
B)
Copper OFHC C10200
MgB2
Monel 400
Currently produced in three sizes (w x t): 2.5 x 1.5, 2 x 1, 1.5 x 0.7 mm
Monolithic design -2 Type A): Standard Columbus MgB2 wire with one ring of
superconducting filaments – Iron barrier between the
filaments and the Copper core
 Type B): Newer MgB2 wire with no Iron barrier between
the filaments and the Copper core – higher engineering
critical current and no Iron content in the conductor,
MgB2 filaments more near to the neutral plane to
enhance resistance to bending – long lengths under
development
 Drawback of the monolithic wire design: Copper fraction
hard to be varied significantly
Expected wire performance evolution with
respect to time
Type A) wire
Time
Process
Je (A/mm2) at 12K, 2 T
Je (A/mm2) at 12K, 4 T
Now
Carbon doping
200
130
End 2010
Ball milling
300
200
End 2011
Improved Boron
450
350
2012
High pressure process
700
500
 For type B) wire we do expect 10% higher Je
 Je calculated overall (entire wire cross section)
 Je at first approx is independent from the overall wire cross
section S, i.e. Ic can be calculated by Ic=Je x S
 For approximate numbers at 20K, just divide magnetic field by
a factor of two ( i.e. Je at 20K, 2 T ~ Je at 12K, 4 T)
Wire unit length/strength
 Currently Columbus can treat about 4 dm3 of material
in one step
 This means a single batch length of 2 Km for the 2 x 1
mm wire, or 4 Km for the 1.5 x 0.7 mm wire
 Scaling up by a factor of two is expected by modifying
actual equipment
 Further scaling up by a factor of four is expected by
purchasing of additional equipment – subcontracting
initial drawing to Fornaci
 Wires are conceived for R&W device manufacturing;
minimum bending diameter with no degradation is
approximately 100 times the conductor thickness
 Maximum tensile strain with no degradation is about
200 MPa
Other wire configurations
 These conductors are conceived for conventional magnet
application
 Different wire designs can be produced according to
customers request (low AC-losses, high filaments count,
wire-in-channel, etc.)
Sandwich conductor is becoming our best proposal for a
magnet wire – f.f. of 30%, adjustable Copper fraction, lower
cost, higher overall je, easier than WIC for MgB2
Production process and costs
Cost estimate
Manpower
Raw material cost
Metallurgical phase
Chemical phase
10%
+
B
+
Mg
B + Mg
90%
+
reaction at
900°C in Ar
MgB2
The production process is composed by two phases, a
chemical one followed by a metallurgical one
Such process is very effective in producing very homogeneous,
long conductors, and it is easily scalable to long length
manufacturing, reducing than the manpower costs
dramatically
Ni
Manpower expected at
same level than NbTi
when production will
increase
Costs of Boron and
Magnesium are small
compared to other materials
Currently, wire costs are driven by Nickel sheath
Replacing with stainless or low-carbon steel will
help in dropping the cost down to the same level
of NbTi when production will exceed 5’000
km/year
Demonstrators of Columbus MgB2
Technology
Texas Center for
Superconductivity
1 Tesla cryogenic-free
solenoid magnet
INFN-Genova
2.35 Tesla dipole magnet
for particle accelerators
ASG Superconductors
Open-Sky MRI
Recent R&W magnets
made with our MgB2 wires
many more to come soon
SINTEF Norway
Induction heater
Ansaldo Breda CRIS
1 Tesla cryogenic-free
solenoid magnet
Cesi Ricerca
LNe Fault current limiter
Chinese Academy of
Science
1.5 Tesla cryogenicfree solenoid magnet
The MRI system “MR Open”
Main Magnet Parameters
Nominal Field
0.5 T
Peak Field on the Conductor
1.3 T
Nominal Current
90 A
Number of Pancakes
12
Conductor Length (total)
18 Km
Inductance
60 H
Overall Dimensions
2x2x2.4 m
Patient Available Gap
0.6 m
Weight
25000 Kg
6 magnet systems produced this year – 2 to 4 systems will
be shipped to customers worldwide by end of the year
First
commercial
system
installed in
hospital
Superconducting junction
Persistent mode operation test, about
300Ampere @20Kelvin, filtered
361
Magnetic field (Gauss)
MgB2 Columbus Superconductors
standard production tapes.
Persistent mode operation
(R<10-14Ohm) on few turns
samples (260mm diameter):
-Single joint: up to 300 A @20K,
self-field
-Double joint: up to 200 A @20K,
self-field
-Latest results show that joints
with 300 A at 25 K, > 500 A at
20K critical currents are
achievable
In progress: s.c. switch
About 15 hours of settling time
360
Δ
B
=
0
.
0
5
G
a
u
s
s
359
358
0
5
10
Time (Days)
Persistent mode
operation solenoid
15
New Induction Heater design
=90%
New design with DC induction heating
Objectives of ALUHEAT are:
•to dramatically reduce energy consumption and life-cycle costs in one of the large-scale
electrotechnical components with poorest energy efficiency and at the same time improve the
production quality
•To validate the technical and economical feasibility of the new concept by building a 200-300 kW
aluminium billet induction heater and test it in an industrial aluminium extrusion plant
Construction of the heater
MgB2 based coils have been already realized and
tested individually: 32 double pancakes with 550 m
each, and the magnet will be operated at 20K, 1.5 T
Cryogenic system has been recently tested – One of
the two superconducting coils has been tested
successfully to rated current – the full system will be
tested in beginning of 2010
Design of an MgB2 feeder system to connect
groups of superconducting magnets to
remote power converters
First test of
the 3 kA cable
successfully
completed at
CERN using
our strands –
Ic exceeded 11
kA at 4.5 K
and self field,
probably
reaching the
optimal target
of 3 kA up to
30 K
20kV distribution system DC resistive
FCL design based on MgB2
Nominal Rate
25 MVA
Nominal Voltage
20 kV
Quenching current
1225 A
Inductance
5 mH
Quenched resistance
5
Cross section
Number of MgB2 filaments
Superconducting section
Stabilization material
Sheath material
Quenched resistance per unit length
2.30  1.10 mm2
8
19.1 mm2
Cu
Steel
0.1 /m
Racetrack magnet for particle
accelerators – MARIMBO project
The magnet reached
about 2.5 Tesla in
cryogenic-free
conditions
Magnet was R&W with
a layer by layer
structure
Ignitor – italian fusion project
30K He gas cooled
copper conductors
are currently
expected to be
used in this
machine
Parameters
Major Radius
Unit
m
Aspect ratio
Elongation
Triangularity
Symbol Value
R0
1.32
0.47,
a,b
0.86
A
2.8
k
1.83
d
0.4
Toroidal magnetic field
BT
T
Toroidal current
Ip
Maximum poloidal field
Bp,max
Minor radius
Mean poloidal field
13
11
m
MA
6.5
T
3.44
T
MA
Poloidal current
Iq
9
Edge safety factor (@11MA)
qy
3.6
Confinement strenght
Plasma Surface
Plasma Volume
S0
V0
38
34
10
MA T
m2
m3
ICRF heating (140 MHZ)
PRF
6 (*)
MW
MgB2 cable conductor for Ignitor
Conclusions
 MgB2 industrial production is making a
substantial progress
 A first commercial product has been already
introduced into the market (LHe-free MRI)
 Many more prototypes and demonstrators are
currently under development worldwide
 Low-cost and mechanical strength are essential
requests for MgB2 to be competitive
 In-field performance still needs to be improved
in order to enable effective Nb3Sn replacement
in high-field magnets
Thank you for your attention!