1. Nb3Sn Cable and Insulation for LARP High-Gradient Quadrupole Magnets
US LHC Accelerator Research Program
bnl - fnal- lbnl - slac
Nb3Sn Cable and Insulation for LARP High-Gradient Quadrupole Magnets
D.R. Dietderich
Lawrence Berkeley National Laboratory

2. 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 mm and mm
Insulation development
LARP TQ cable
Nov. 16, 2011
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

3. 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~ 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
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

4. 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
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

5. 2 Pass Cable with MgO Paper & S-glass Cores
Nov. 16, 2011
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

6. 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, 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
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

7. 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 microns
To mm mm
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
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

8. 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 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 mm diameter strand
Nov. 16, 2011
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

9. HQ Cable Parameters of R&D CablesTQ LQ
Old HQ cable
HQ Box
New HQ cable
Zone with
Too much damage
Nov. 16, 2011
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

10. Critical Current Cable 1014 with 34 strands and wire diameter 0.80 mm
Un-deformed
Round
Wire
Extracted
Strands
Gosh (BNL)
A. Godeke (LBNL)
Nov. 16, 2011
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

11. RRR 1014 – 0.80 mm wire Un-deformed Round Wire Nov. 16, 2011
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

12. Critical Current Cable 1015 & 1017 with 35 strands and wire diameter 0
Critical Current Cable 1015 & 1017 with 35 strands and wire diameter mm
36 strands
Un-deformed
Round
Wire
1st Production cable 1017
Extracted strands
Un-deformed
round wire
665C for 48h
650C for 72h
Nov. 16, 2011
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

13. RRR 1015 – 0.778 mm wire Nov. 16, 2011 D.R. Dietderich
Hi Lumi/LARP CM17 CERN

14. Cable 1015 Sections I & L
1015-L
1015-I
No significant sub-element damage is observed in the wire cross-sectional images
Nov. 16, 2011
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

15. 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 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
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

16. Insulation Braided onto Cables
New England Wire
S-glass with 636 sizing
TQ/LQ Cable 10 mm wide
Braid angle 64 deg.
New England Wire
S-glass with 933 sizing
HQ Cable 15 mm wide
Braid angle 55, 60, 64 deg.
Pitch Angle
Thickness
55o
0.103 mm
60o
0.109 mm
64o
0.114 mm
A. Ghosh - BNL
Nov. 16, 2011
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

17. 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
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

18. 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 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 mm
Contains boron – could be an issue.
S2-glass tape
Two layers of tape is > 0.100mm ( mm)
Consider making braided insulation thicker to match
Consider single layer of tape mm thick
Nov. 16, 2011
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

19. Extra slides

20. R&D to Reduce HQ Cable Dimensions
New cable parameters:
Mid-thickness mm from 1.44 mm
Width mm from mm
Keystone angle 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
D.R. Dietderich
Hi Lumi/LARP CM17 CERN

21. 1 Pass Cable with Stainless Steel Core
Nov. 16, 2011
D.R. Dietderich
Hi Lumi/LARP CM17 CERN