nb 3 sn cable and insulation for larp high-gradient quadrupole magnets

Nb3Sn Cable and Insulation for LARP High-Gradient Quadrupole Magnets

D.R. DietderichLawrence Berkeley National Laboratory

bnl - fnal- lbnl - slacUS LHC Accelerator Research Program

Nov. 16, 2011

D.R. DietderichHi Lumi/LARP CM17 CERN

Outline of the Presentation

• Cabling Philosophy for Rutherford Cables– 1 Pass and 2 Pass cables

• Cored cables

• R&D to reduce HQ cable dimensions– With wire diameters of 0.778 mm and 0.800 mm

• Insulation development

LARP TQ cable

Nov. 16, 2011


LARP Cable Fabrication – 2 Pass

• 2 pass process was developed to reduce dimensional changes of a cable during coil processing and reaction– A cable is fabricated oversize in thickness, annealed (200C for

2-4 hrs), and re-rolling to final thickness.• The anneal reduces the residual stress in the cable and the cable

typically shortens by 0.20 – 0.25%.

• Very important -- Cable is permitted to get wider during the second pass – 2nd pass roll are~ 50-100 microns wider

• If a cable is too narrow --

• Strain localized to 3 strands at the edge of a cable due to friction between rolls and strand

Nov. 16, 2011


LARP Cable Fabrication – 1 Pass

• 1 pass process has been developed for adding stainless steel (SS) cores to cables– Strand is annealed (190C for 4 hrs)

prior to cabling

– Cable is made in 1 pass to final dimensions

• Due to mechanical differences between the strand and the SS core a 2 pass process is not possible.

• However, other core materials such as S-glass tape or MgO paper tape could be made in 2-pass.

Un-reacted Reacted wire

Ductility check

Nov. 16, 2011


2 Pass Cable with MgO Paper & S-glass Cores

Nov. 16, 2011


Cored Cables (HQ-1012) Used in HQ Coil 12

• HQ cable 1012 (old cable parameters)– 35 strands with diameter of 0.80 mm– 1.44 mm mid-thickness,

• Did not increase mid-thickness with of core addition– 15.1 mm wide– 0.75 deg. Keystone angle– 8 mm wide, 0.025 mm thick stainless steel core

• Biased to thick edge of cable

– Core biased toward thick edge of the cable

• No fabrication issue with the addition of a SS core• Addition of the core did not degrade the Ic

– Measurements show a reduction of 3-5 % which is typical for an HQ cable without a core

Mandrel with slot for adding a core

Nov. 16, 2011


Objective of Cable R&D• To permit the use of existing HQ tooling

– The cable dimensions needed to be reduced to:– Provide more space azimuthally (i.e. thinner cable)– Provide more radial space (i.e. narrower cable)

• Cable R&D targets dimensions: – Reduce HQ cable thickness by 65-100 microns

• To 1.375 mm - 1.340mm

– Width target is < 15mm (14.7mm -15mm) • Accommodates dimensional changes of cable during

reaction• Thicker insulation or more insulation between layers and

tooling

– Keystone angle un-changed at 0.75 deg.

Nov. 16, 2011


HQ Cable R&D to Reduce Cable Size

• The next slide shows the thickness and width of several cable samples – Cable 1014

• 34 strands with a diameter of 0.80 mm– Cable 1015

• 35 strands with a diameter of 0.778 mm

• “Blue Box” denotes the target parameters needed to accommodate the cable dimensional changes in the present tooling.– The box with dashed lines are the parameters

deduced from R&D on TQ and LQ coils• “Red Circle” denotes the new HQ parameters

with the 0.778 mm diameter strand

Nov. 16, 2011


HQ Cable Parameters of R&D Cables

Width vs. Thickness for cables 1014 and 1015

14.70

14.75

14.80

14.85

14.90

14.95

15.00

1.32 1.33 1.34 1.35 1.36 1.37 1.38 1.39 1.40 1.41 1.42

Thickness (mm)

Wid

th (

mm

)

1014

1015

1014- P2 1014- P1

1014- R51014- S

TQ LQ

New HQ cable

HQ Box

Zone with Too much damage

Old HQ cable

Nov. 16, 2011


Critical Current Cable 1014 with 34 strands and wire

diameter 0.80 mm Ic (11T, 4.2K) vs. Thickness of Cable 1014

750

760

770

780

790

800

810

820

1.30 1.35 1.40 1.45 1.50 1.55 1.60 1.65

Mid-Thickness (mm)

Cri

tic

al C

urr

en

t (A

)

LBL 1014 Narrow rolls

LBL RW in 1014

BNL 1014 Narrow rolls

BNL RW in 1014

BNL 1014 Wide Rolls

Un-deformed Round Wire

ExtractedStrands

A. Gosh (BNL)A. Godeke (LBNL)

Nov. 16, 2011


RRR 1014 – 0.80 mm wire

RRR of 1014

0

20

40

60

80

100

120

140

160

180

1.30 1.35 1.40 1.45 1.50 1.55 1.60 1.65

Cable mid-Thickness

RR

R

LBL 1014 RRR

BNL 1014 RRR Wide Rolls

BNL 1014 RRR Narrow Rolls


Nov. 16, 2011


Critical Current Cable 1015 & 1017 with 35 strands and

wire diameter 0.778 mm

Un-deformed round wire

Ic (11T, 4.2K) vs. Thickness of Cable 1015

710

720

730

740

750

760

770

780

790

800

810

1.30 1.35 1.40 1.45 1.50 1.55 1.60

Mid-Thickness (mm)

Cri

tic

al C

urr

en

t (A

)

LBL 1015

LBL RW in 1015

BNL 1015

BNL 1015 36-strands

BNL RW in 1015

36 strands


Extracted strands

1st Production cable 1017

650C for 72h665C for 48h

Nov. 16, 2011


RRR 1015 – 0.778 mm wire

RRR of 1015

0

20

40

60

80

100

120

1.3 1.35 1.4 1.45 1.5 1.55 1.6

Cable mid-Thickness

RR

R

LBL 1015 RRR

BNL 1015 RRR

Nov. 16, 2011


Cable 1015 Sections I & L

• No significant sub-element damage is observed in the wire cross-sectional images

1015-L

1015-I

Nov. 16, 2011


Cable -- Summary• A stainless steel core can be added to the standard HQ

cable without significant loss of critical current• Standard HQ cable with 0.80 mm diameter wire could

have be decreased in thickness and width to meet the target parameters (HQ box) – However, the risk of damaging to the strand was considered to

great with addition of a corfe – i.e. reduced processing margin. • New HQ cable uses a 0.778 mm diameter strand to

achieve the new cable parameter • The critical current variation in cable 1015 is not

understood but could be due to: – Sample handling while preparing for Jc testing. – Or localized damage in some strands during cabling. – Suggests that a cable testing facility is needed for accurate

cable critical current measurements. • RRR was reduced slightly by cabling

Nov. 16, 2011


Insulation Braided onto Cables

New England WireS-glass with 636 sizing

TQ/LQ Cable 10 mm wideBraid angle 64 deg.

New England WireS-glass with 933 sizingHQ Cable 15 mm wide

Braid angle 55, 60, 64 deg.

A. Ghosh - BNL

Pitch AngleThickness

55o

0.103 mm

60o

0.109 mm

64o

0.114 mm

Nov. 16, 2011


Tape Winding

• LBNL having vendor fabricate tape winding machine– Demo video

• FNAL has an established process with E-glass– 2 layers– Thickness

~0.100mm

Nov. 16, 2011


Summary – Insulation Options

• Braided insulation onto cable – Primary option– New England Wire

• S2-glass with 636 and 933 sizing – Requires cleaning of insulated cable

– thickness of 0.103-0.114 mm

• Plan to develop process for fibers with Silane sizing

– Revolution Composites • S2-glass – Also makes sleeve • New company but with staff from EDO Fiber Innovations

• Tape options – Second option– E-glass 2 layers can produce 0.100 mm

• Contains boron – could be an issue.

– S2-glass tape• Two layers of tape is > 0.100mm (0.125-0.150 mm)

– Consider making braided insulation thicker to match • Consider single layer of tape 0.100 mm thick

Extra slides

Nov. 16, 2011


R&D to Reduce HQ Cable Dimensions

• New cable parameters: – Mid-thickness 1.375 mm from 1.44 mm– Width 14.80 mm from 15.10 mm– Keystone angle 0.75 deg. Unchanged

• New cable designs will provide more space in tool for cable dimensional changes– Have made the first production cable 1017 with new parameters

• HQ coil 14 has been fabricated and is ready to test in a mirror.

– Have just made a cored cable with the new cable parameters with a strand diameter of 0.778mm.

• Coil winding with the cored cable was OK – However, popped strands were produced going around the pole

• They are pushed back into position and winding continues

– Planning to cut HQ coil 12 into sections for inspection.

Nov. 16, 2011


1 Pass Cable with Stainless Steel Core

Frequency, f, Hz

0.00 0.02 0.04 0.06 0.08 0.10

To

tal

per

-cy

cle

loss

, Qt,cal,

104 J

/m3

0

5

10

15

20

25

Cable 1 Cable 2 Cable 1A

FO

EO

nb 3 sn cable and insulation for larp high-gradient quadrupole magnets

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