Strand and Cable R&D

D. Turrioni, Fermilab

1st FNAL-CERN Collaboration Meeting Fermilab, May 13, 2011

Strand and Cable

Outline

• Cable and Strand Specifications• Cabling machine, tooling and instrumentation• Cable study and development• QA/QC• Summary

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Strand and Cable

Cable Specification

• The large aspect ratio of the cable and the present cabling procedure require the cable fabrication in two stages: the rectangular cable with narrower width and lower packing factor and the keystone cable with final parameters

• Long Unit Length ~ 210 m

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ParameterValue

Cable Cross SectionUn-reacted ReactedCable unit length, m 210 Rectangular KeystonedNumber of strands 40Transposition angle, degree 15Transposition direction Left-hand screwMid-thickness, mm 1.269 1.307Thin edge, mm 1.167 1.202Thick edge, mm 1.370 1.411Width, mm 14.70 14.847Key-stone angle, degree 0.79 0.81Insulation thickness, mm 0.150 0.100

Strand and Cable

Strand Specification

• Nb3Sn RRP-108/127 strand produced by Oxford SC Technology

• Relatively Stable Strand@ 4.5 K and 1.9 K• High Jc

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Parameter Value Strand cross-section Process ternary RRP

Strand diameter, mm 0.700±0.003 Strand cross-section design 108/127 Cu fraction, % 53±3 Effective sub-element diameter, µm <60 Critical current Ic(12T, 4.2K), A >475 Critical current density Jc(12T, 4.2K), A/mm2 >2650 RRR (after heat treatment) >60 Twist pitch, mm 14±2 Twist direction right-hand screw Minimum piece length, m >550

Strand and Cable

Cabling Machine

• Compact machine.• Two major upgrades :

– Continuous cable pitch regulation with the electronic synchronization of the main wheel and the caterpillar motion

– 42-spool wheel• Max Speed of 5 m/min

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Respooler

Strand and Cable

Cable Forming Fixtures

Turk head

Keystoning Tooling

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Side Rollers and Mandrels

Strand and Cable

Instrumentation

• Measurements of the two dial indicators are acquired every 3 cm at 1 m/min of production speed.

Mitutoyo Digimatic

Multiplexer MUX-10

Turk head Mitutoyo Dial Indicator ( 1 µm

resolution )

Keystoning tooling Dial Indicator ( 1 µm

resolution )

Mitutoyo Micrometer ( 1 µm resolution )

PC

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Strand and Cable

Cable Measurements40 Strands cable for practice coil

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0 50 100 150 200 250 3000

0.01

0.02

0.03

0.04

0.05

0.06Top Roller Dial indicator

Cable Length [m]

Dial

Indi

cato

r Rea

ding

[mm

]

Thickness 1.318±0.011 mmWidth 14.580±0.04 mmLay Angle 14.5ºPF 81.9 %

Thickness 1.297±0.004 mmWidth 14.591±0.023 mmLay Angle 15ºPF 83.4 %

Dial reading 0.019±0.002 mmMax-Min = 0.010 mm

Strand and Cable

Cable development

• Design and parametric considerations were used in the development of the cables to be made of Nb3Sn RRP wires.

• For the cable geometry contemplated by the magnet designers the mandrel was designed in order to provide sufficient room for the strands to wind around it without excessive damage.

• This requirement, which accompanied the requisites for mechanical stability, allowed determining quite accurately the number of strands needed for each cable geometry.

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Strand and Cable13 May 2011, FNAL-CERN CM1 D. Turrioni10

A large body of data acquired during Nb3Sn conductor development shows that when cabling Nb3Sn RRP wires, it is important that:

Cable Design Parameters•The geometrical relationship between a cable of desired width wC, to be obtained with strands of diameter d, and the required mandrel width wm is shown in the first expression below where is an empirical factor determined by experiment. •The second expression is a simplified formula used for the purpose of parameterizing the number of strands needed for each cable geometry. N is the number of strands in the cable, the cable lay (or pitch) angle

≥ 1

8 10 12 14 16 18 2038

39

40

41

42

43

44 14.7 mm cable, 0.7 mm strand15.1 mm cable, 0.7 mm strand

Pitch Angle,

No.

Str

ands

TD-10-022 “Nb3Sn Cable Development for the 11 T Dipole Program”

Strand and Cable

40 Strands Cables List

• Next slides show results of:– Five Rectangular copper practice cables with and without core– Two rectangular Nb3Sn practice cable with and without core (108/127 strand design)

– One Keystoned Nb3Sn practice cable without core (114/127 strand design)

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Cable Traveler Name Type Length, m

Strand design

No. strands

Strand size, mm

Mandrel width, mm

Lay angle, degree

PF, %

SS Core

R&DT_101007_40_1_0 R 50 Cu 40 0.697 13.93 15 83.4 NR&DT_101026_41_1_0 R 50 Cu 41 0.697 14.24 15.5 84.0 “R&DT_101101_40_1_1a R 50 Cu 40 0.697 13.95 15.5 83.8 Yb

R&DT_101101_40_1_1b R 50 Cu 40 0.697 13.95 17.5 85.1 Yb

R&DT_101109_40_1_0 R 10 RRP108 40 0.703 13.95 15 82.8 NR&DT_101109_40_1_1 R 10 RRP108 40 0.703 13.95 15 83.7 Yb

R&DT_110103_40_1_0 R 325 Cu 40 0.699 13.63 15 83.7 NR&DT_110315_40_1_0 K 230 RRP114 40 0.703 13.92 15 86.3 NR&DT_110315_40_1_0 Ka 15 RRP114 40 0.703 13.92 15 85.8 NR&DT_110420_40_1_0 R 190 Cu 40 0.697 13.92 15 83.4 N

a Rectangular cable has been annealed in Argon at 180 Cº for 1 hrb Stainless steel core used was 9.525 mm x 25 mm in size.

Strand and Cable

Cable development Rectangular Copper Cables

• The first forming step of the rectangular cables to be used to produce keystoned cables 14.7 mm (with 40 strands) and 15.1 mm (with 41 strands) wide was finalized out of hard Cu wires of 0.7 mm nominal diameter.

• The rectangular cables were 1% narrower than the final desired widths of the keystoned cables in order to account for the 1% width expansion to be expected when performing the second, keystoning, cabling step.

• Selected design was the 40 strand cable because of CERN cabling machine capability

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a Stainless steel core used was 9.525 mm x 25 mm in size.

Cable Traveler Name Length, m No. strands Strand size,

mmMandrel

width, mmLay angle,

degreePF, %

SS Core

R&DT_101007_40_1_0 50 40 0.697 13.93 15 83.4 NR&DT_101026_41_1_0 50 41 0.697 14.24 15.5 84.0 “R&DT_101101_40_1_1a 50 40 0.697 13.95 15.5 83.8 Ya

R&DT_101101_40_1_1b 50 40 0.697 13.95 17.5 85.1 Ya

Strand and Cable

Cable development Rectangular Nb3Sn

• To verify the impact of the cabling process on the actual superconductor that will be used in the magnet short model two 40 strands superconducting cables were produced.

• Strand design RRP 108/127, 0.7 mm• The appropriate electrical and microstructural

characterizations were done

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Cable Traveler NameLength,

mLay angle,

degreePF, %

SS Core

Cable width ±σ, mm

Cable thickness ±σ, mm

R&DT_101109_40_1_1 6.71 15 83.7 Ya 14.61±0.02 1.331±0.003

R&DT_101112_40_1_0 7.5 15 82.8 N 14.62±0.02 1.328±0.003

a Stainless steel core used was 9.525 mm x 25 mm in size.

Strand and Cable

Damage Analysis

• 6 cross sections of each cable (with and without core) are studied.

• Both cables show very little internal damage.

• These cables show less than average strand damage.

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Cable name

RRP Strands

used

No. cross sections analyzed

Strands w/Damage

Broken subelements

Min./Max. Merged

subelementsDamaged

subelementsR&DT_101109_40_1_1 (w/core) 108/127 6 1 2 0/2 2R&DT_101112_40_1_0 (no core) 108/127 6 0 0 0 0

Damage Details

Cable cross section with core

Strand and Cable

Electrical characterizationRectangular with core

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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 160

200

400

600

800

1000

1200

1400

1600

1800

2000Extracted from Cored Cable V-H @ 4.2K Sample#2Round V-H @ 4.2KPower Supply LimitExtracted from Cored Cable V-I @ 4.2K Sample#1Extracted from Cored Cable V-H @ 4.2K Sample#1Extracted from Cored Cable V-I @ 4.2K Sample #2Round V-I @ 4.2K

Magnetic Field [T]

Curr

ent [

A]

Ic, Jc @14T Ic , Jc @12 T Is 0-4T Is 4-8T RRRExtracted Cored cable #1 288,1626 468,2643 950 575Extracted Cored cable #2 248,1400 424,2400 925 975 182Round 275,1553 455 ,2570 1175 775

In VI Tests, solid markers stands for Iquench

evaluated from full transition, whereas empty markers stands for the maximum current reached by sample before quench with no visible transition.

Strand and Cable

Electrical characterizationRectangular without core

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In VI Tests, solid markers stands for Iquench

evaluated from full transition, whereas empty markers stands for the maximum current reached by sample before quench with no visible transition.

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 160

200

400

600

800

1000

1200

1400

1600

1800

2000Extracted from Uncored Cable V-I @ 4.2K Sample#1Extracted from Uncored Cable V-H @ 4.2K Sample#1Round V-I @ 4.2KRound V-H @ 4.2KPower Supply LimitExtracted from Uncored Cable V-I @ 4.2K Sample #2Extracted from Uncored Cable V-H @ 4.2K Sample#2

Magnetic Field [T]

Curr

ent [

A]

Ic,Jc@14T Ic ,Jc@12T Is 0-4T Is 4-8T RRRExtracted UnCored cable #1 282,1593 464 ,2620 1225 800Extracted UnCored cable #2 262,1479 414 (Imax) 1200 725 232Round 275,1553 455,2570 1175 775

Strand and Cable

Keystoned cables• After the first stage of rectangular cable study was

completed and the new rollers for the keystoning fixture commissioned the second stage was to make keystoned cables.

• The attempt to make in a single pass a keystoned copper cable was not completely successful. The cable formed but roped entering the keystone wheels in the first 80m.

• The decision was to finish the remaining 245m rectangular and to make a second rectangular copper cable to be wound in a practice coil.

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Strand and Cable

Rectangular Copper Practice Cable #2

• Cable was fabricated for winding a practice coil.

• Cable was well formed and to size

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Cable Traveler NameNo.

strandsStrand

size, mm

Mandrel width,

mmCable width,

mm

Cable thickness,

mm

Lay angle, degree

PF, %

SS Core

Length, m

R&DT_110301_40_1_0 40 0.696 14.05 14.76 1.237 15 86.2 N 250

Left Side view

Top view

Right Side view

Strand and Cable

Keystoned Nb3Sn cable• Nb3Sn Keystoned 40 strands cable was made in two passes.• 114/127 Strand design• The cable strands diameter except one was originally 1 mm drawn to

0.7 mm.• In the first pass 250 m of rectangular cable was made.• A piece of 15 m of the rectangular cable was cut and annealed in

argon atmosphere for 1 hour at 180 ºC.• The two cables , annealed and not, were keystoned.• Microstructural analysis of cable cross sections and electrical

characterization of extracted samples were performed.

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Cable Traveler Name Type Length, mMandrel

width, mmLay angle,

° PF, %Cable width±σ,

mmCable

thickness±σ, mmR&DT_110315_40_1_0 R 248.4 13.92 15 84.04 14.556±0.038 1.316±0.009R&DT_110315_40_1_0 Ra 15 13.92 15 84.1 14.599±0.039 1.309±0.005R&DT_110315_40_1_0 K 230 - 15 86.3 14.71±0.012 1.265±0.005R&DT_110315_40_1_0 Ka 15 - 15 85.8 14.69±0.02 1.274±0.005

Keystoned no annealed

Keystoned annealed

RRP 114/127

a Rectangular cable has been annealed in Argon at 180 Cº for 1 hr

Strand and Cable

Damage AnalysisNb3Sn KS Cable

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Rectangular

Keystoned

RectangularReacted

KeystonedreactedKeystoned AnnealedReacted

• Several cross sections from keystoned, rectangular, keystoned annealed, reacted and unreacted cable were analyzed.

Rectangular cable edges

Strand and Cable

Damage AnalysisNb3Sn KS Cable (cont’d)

Cable Traveler Name Type Reacted No. CSNo of Strands w/ possible damage

Total No. broken

subelements

Min/Max. No. merged

subelementsNo. Damaged Subelements

R&DT_110315_40_1_0 R N 6 0 0 0/0 0R&DT_110315_40_1_0 K N 6 4 15 5/5 15R&DT_110315_40_1_0 R Y 6 1 2 0 2R&DT_110315_40_1_0 K Y 6 6 13 14/14 16R&DT_110315_40_1_0 Ka Y 6 2 3 0/2 3

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• 6 cross sections of each Type (Rectangular, Keystoned, Keystoned annealed) are studied.

• Keystoned cable shows an average strand damage.

• The annealed cable shows less than average strand damage.

a Rectangular cable has been annealed in Argon at 180 Cº for 1 hr

Strand and Cable

Electrical characterizationNb3Sn KS Cable

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Ic ,Jc@ 14 T Ic ,Jc@ 12 T Is 0-4T Is 4-8T RRRKeystoned 9772-2A #1 HT269 266, 1382 442, 2297 925 750 150Keystoned 9772-2A #2 HT269 268, 1393 447, 2323 1300 825 280KS Ann. 9772-2A #1 HT270 302, 1569 482, 2505 950 >900 230KS Ann. 9772-2A #2 HT270 307, 1595 489, 2541 950 750 196Rect. 9772-2A #1 HT270 306, 1592 493, 2564Round 9772-2A HT 269 260, 1351 440, 2287Round 9772-2A HT 270 267, 1388 451, 2344 1475 1000 300

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 160

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2000KS V-IKS V-HKS Annealed V-I #1KS Annealed V-H #1KS Annealed V-I #2KS Annealed V-H #2Round HT KS Annealed V-IRound HT KS Annealed V-H

B[T]

Curr

ent [

A]

4.2 K

In VI Tests, solid markers stands for Iquench

evaluated from full transition, whereas empty markers stands for the maximum current reached by sample before quench with no visible transition

Strand and Cable

Cable Readiness Review• An internal readiness review of the 11

Tesla dipole cable was held on May 02, 2011.

• The following aspects were reviewed:– Procedure – Documentation (Traveler, Logbooks)– Infrastructures (Cable Machine, Tooling)

• Overall their were no major or minor findings

• Starting cable fabrication for the demonstrator coils

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Front page of the cable traveler

Strand and Cable

Cable Map OXFORD

RRP 108/127

BILLET # SIZE METERS DATE REC.12292-1 0.7mm 1871.5 Aug.31.1012292-2 0.7mm 1665 Aug.31.10

12292-3a 0.7mm 600 Aug.31.1012292-3b 0.7mm 700 Aug.31.1012292-3c 0.7mm 2776 Aug.31.1012292-3d 0.7mm 567 Aug.31.1012319-1a 0.7mm 1647 Aug.31.1012319-2 0.7mm 2140 Aug.31.1012521-1 0.7mm 410 Aug.31.1012521-2 0.7mm 2599 Aug.31.1012522-1 0.7mm 427 Aug.31.1012522-2 0.7mm 462 Aug.31.1012522-4 0.7mm 714 Aug.31.10TOTAL 16578.5

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OXFORD RRP 108/127BILLET # SIZE METERS DATE REC.13062-1 0.7mm 636 Mar.23.1113062-2 0.7mm 554 Mar.23.1113062-3 0.7mm 952 Mar.23.1113062-4 0.7mm 443 Mar.23.1113062-5 0.7mm 359 Mar.23.1113062-6 0.7mm 1998 Mar.23.1113062-7 0.7mm 1012 Mar.23.1113062-8 0.7mm 2793 Mar.23.1113063-1 0.7mm 2411 Mar.23.1113063-2 0.7mm 722 Mar.23.1113063-3 0.7mm 3625 Mar.23.1113063-4 0.7mm 2273 Mar.23.1113063-5 0.7mm 713 Mar.23.1113090-1 0.7mm 469 Mar.23.1113090-2 0.7mm 2011 Mar.23.1113090-3 0.7mm 601 Mar.23.1113090-4 0.7mm 784 Mar.23.1113090-5 0.7mm 2456 Mar.23.11TOTAL 24812

• 1 UL→ 210 m• 3 UL for a long cable + 1 UL + 60 m for the analysis• Cable fabrication for 11T Demo Coils in progress

Strand and Cable

Summary

• Cable has been designed• Technology developed and experiments verified• Reviewed• Cable Fabrication in progress

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Strand and Cable

R&D steps

• Fabrication and test of Cored Cables• Longer UL (650 m) for 5.5 m long coil• New Strand Design–RRP-151/169 from OST–R&D strand from Hyper Tech, Inc.–PIT strand from CERN

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