development of high current nb 3 sn rutherford cables for ned and larp
DESCRIPTION
Development of High Current Nb 3 Sn Rutherford Cables for NED and LARP. D.R. Dietderich, A. Godeke, N.L. Liggins, and H.C. Higley WAMSDO, May 2008. Outline. Rutherford cables Cabling objective: Damage free strand Mechanically stable for winding a magnet Review cabling history for LBNL - PowerPoint PPT PresentationTRANSCRIPT
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL1
Development of High Current Nb3Sn Rutherford Cables for NED and LARP
D.R. Dietderich, A. Godeke, N.L. Liggins, and H.C. Higley
WAMSDO, May 2008
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL2
Outline
• Rutherford cables• Cabling objective:
– Damage free strand– Mechanically stable for winding a magnet
• Review cabling history for LBNL – Dipole D-20 (13.5/14.5T)– Recent rectangular cable fabrication for LBNL magnets
• RD-3 series (14.7 T)• HD-1 series (16 T)
• Cables for LARP Technology Quadrupoles (TQ)• Proto-type cables for Next European Dipole (NED)
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL3
60 Strand Machine for Fabricating Rutherford Cables
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL4
Typical Rutherford CableCable 961
Edge deformations are important
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL5
Good and bad cable edge deformation
• Bad • Good
Main difference is different width of the cable
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL6
Managing edge deformationProblem with Packing Factor
Two Cables have equal area but are NOT the same
17.4 mm x 1.400 mm = 24.4 mm2
17.0 mm x 1.435 mm = 24.4 mm20.8 mm strand diameter40 Strand cable
Cable Area = 24.40 mm2
87% Packing Factor
2 Cables: Same compaction orPacking Factor
0.4 is mm half a strand diameterThis difference can be fatal
Design for this strand configuration
at edge of cable
NOT this strand Configuration
t
w Bad
Good
Decoupling of Thickness & Widthas opposed to Packing Factor
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL7
Deformation Parameters t and w
• Thickness deformation t (~strain)t = (cable thickness/2x strand diameter) -1
• Width deformation w (~strain)w = (cable width – theoretical width)/(th. width)
Theoretical width =
PA = Cable pitch angle
(factor 0.72 d not included in plots in this presentation)
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL8
Rutherford Cable Parameter Space
Cable widerw larger
Cab
le th
inne
rt m
ore
nega
tive
No strand deformation at (0,0)2 wire diameters
(t=0)
Theoretical width (w=0)
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL9
Parameter space cables for D-20, RD-3, and HD-1
LBL Cable # 523 MJR-TWCA
LBL Cable # 522 IGC-Int. Tin
LBL Cable # 805ROxford-ORe
D-20 RD-3Internal Tin, MJR, and RRP
-0.40
-0.35
-0.30
-0.25
-0.20
-0.15
-0.10
-0.05
0.00
-0.04 -0.02 0.00 0.02 0.04 0.06 0.08
Width Parameter
Th
ickn
ess
Par
amet
er
D-20 Outer D-20 InnerRD-3 & HD-1LHC-HGQ
Abandoned
RD-3HD-1
Rect. D-20
Key. D-20
NbTiLHC-HGQ
Keystoned D20 cables had ~20% loss in Icand were more sensitive to transverse stress
D-20 is Cosine Theta Dipole (14.7T), RD-3 is Racetrack Dipole, and HD-1 is High Field Dipole (16T)
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL10
Internal Tin, MJR, and RRP
-0.40
-0.35
-0.30
-0.25
-0.20
-0.15
-0.10
-0.05
0.00
-0.04 -0.02 0.00 0.02 0.04 0.06 0.08
Width Parameter
Th
ickn
ess
Par
amet
er
D-20 Outer D-20 InnerRD-3 & HD-1LHC-HGQ
Zones of interest from cables for D-20, RD-3, and HD-1
LBL Cable # 523 MJR-TWCA
LBL Cable # 522 IGC-Int. Tin
?Damaged Zone
Good Zone
LBL Cable # 805ROxford-ORe
MechanicallyUnstable
Abandoned
D-20 RD-3RD-3HD-1
Rect. D-20
Key. D-20
D-20 is Cosine Theta Dipole (14.7T), RD-3 is Racetrack Dipole, and HD-1 is High Field Dipole (16T)
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL11
Technology Quad (TQ) – Cable Specifications & Production
• Spec
• Made
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL12
TQ cable compared to past cables
Internal Tin, MJR, and RRP
-0.40
-0.35
-0.30
-0.25
-0.20
-0.15
-0.10
-0.05
0.00
-0.04 -0.02 0.00 0.02 0.04 0.06 0.08
Width Parameter
Thic
knes
s Pa
ram
eter
D-20 Outer D-20 InnerRD-3 & HD-1LHC-HGQ
Abandoned Keystoned D-20 Cables
RD-3HD-1
Rect. D-20
Key. D-20
NbTiLHC-HGQ
TQ
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL13
Facet size as online probe
• Facet length (x) should be less than Pitch Length/strand (y) – Minor axis
Bad
Good
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL14
Thin edge of cables as online probe
939R
946R
Facets at cable edge SEM Images ofCross Section
Facets > Pitch length/strand
Facets < Pitch length/strand
Bad
Good2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
928R-B 933R 939R 940R 946R 947RCable Number
Maj
or
Axi
s o
f fa
cet
and
PL
/27
(mm
)
Major Axis
PL /27 Strand
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL15
TQ cable widths after re-rolling• Do NOT re-roll cable to
a smaller width – Fabrication (first
rolling)– Anneal cable 200C for
4-6 h– Re-roll (second
rolling) – final cable
9.9
9.95
10
10.05
10.1
928R-B 933R 939R 940R 946R 947R
Cable No.
Cab
le W
idth
(mm
)
Cable Width First Roll
Cable Width
BAD
GOOD
Spec.
After cable 940R the processing was changed
From one set of rollsTo 2 sets of rolls,
One for the fabrication and one for re-rolling
~ 50 micrometer wider
Re-rolling after anneal is used to provide final shape
Process improvement
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL16
Summary of Critical and Stability Currents for TQ Cables
• All cables but 939R: – Reduced Jc(12T,4.2K) by about 0-3%
– Reduced stability current (Is) by ~10%
• Cable 939R (bad example with sheared sub-elements): – Reduced Jc (12T,4.2K) by about ~5% (Only)
– Reduced stability current (Is) by ~50% (RRR loss?)
• Concern – Past Jc measurements on cables with edge damage has shown them to be more sensitive to transverse stress.
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL17
NED Cable Parameters
• LBNL Cable-CALC– Should increase the width from 26 mm to 26.9 mm.
– Note: Removal of 1 strand is only 2.5% Ic reductionbut provides significantly more width margin
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL18
NED Cable Prototype Fabrication
• LBNL cabling machine was pushed to its limits due to the: – Large strand diameter
– High stiffness of the strand
• Higher tension on the strands should make the cabling process easier. – It should permit fabrication of cables with a lower pitch
angle (~16o)
– Plus reduce the gaps between strands
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL19
NED cable edge facet summaryFour short prototype cable sections made
• Facet/Pitch on the minor edge are similar• Section C has the smallest ratio• Section C has 4-8% Ic reduction (T. Boutboul, EUCAS-07 )
Facet Length mm
Pitch Length mm
Facet/PitchCable Pitch Length mm
965-A-Min 4.26 4.76 0.89 190.7965-A-Maj 4.11 4.83 0.85 193.1
965-C-Min 3.17 3.76 0.84 150.5965-C-Maj 3.45 3.76 0.92 150.5
965-D-Min 3.34 3.74 0.89 149.6965-D-Maj 3.65 3.79 0.96 151.5
965-E-Min 3.33 3.75 0.89 150.1965-E-Maj 3.57 3.77 0.95 150.9
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL20
NED spec and prototype
NED PrototypeSpec
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL21
Strand deformation inside a cable
• Dimples at strand cross over points (box) – Deformation not uniform
along a strand – Making cables thinner has
shown no significant impact on performance
– Perhaps cables can be made thinner
• Strand deformation as it goes from the top of cable to bottom (oval) – Limits cable performance
• Need 3D modeling to understand strand deformation at the cable edge
Cable 784R
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL22
Modeling 2D and 3D
3D Modeling of Strand2D Strand Modeling
• S. Farinon, Presented at CHATS-AS 2006
Marco La China
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May 21, 2008WAMSDO, CERN
D.R. Dietderich, LBNL23
Summary
• The facet size on the edge of the cable provides a direct measure of the amount of strand deformation. – Indicates the amount of sub-element distortion inside the strand.
• This work shows that a nearly damage-free mechanically-stable cable can be produced from: – MJR and RRP strands with reduction of only 0-3% Jc (12T,4.2K). – PIT strand with reduction of 4-8% Jc (12, 4.2K)
• Cabling damage (i.e. sheared sub-elements) had minimal effect on Jc but it has a significant impact on strand stability.– The stability current (Is) drops by ~50% in a strand with only a ~5% drop in
Jc at 12T and 4.2K