Coil working group video-meeting

P. Ferracin, J. C. Perez, S. Izquierdo Bermudez, X. Sarasola

February 4th, 2014

Agenda

• Winding test updates

• Nb3Sn-Nb-Ti splice: procedure and fixture

• Single vs. double NbTi leads

• Wire for instrumentation

29/01/2014P. Ferracin 2

29/01/2014P. Ferracin 3

Splicing and tinning tooling

Feb 04, 2014J.C. Perez 4

The same tooling will be used for tinning and splicing using MOB 39 as flux and solder 96/4 Tin/Silver

Sequence of operations

Feb 04, 2014J.C. Perez 5

CuttingTinning

Tool assemblyClamping

Courtesy of Nicolas Peray

Splicing configuration

Feb 04, 2014J.C. Perez 6

Mid-plane shims

Feb 04, 2014J.C. Perez 7

Flux and soldering alloy used at CERN

• Main issue: presence of an oxide layer after reaction.• How to remove this oxide layer?

– Activated fluxes: Improve solderability× But the residue left can lead to corrosion× Essentially banned at CERN

– In SMC and RMC the splicing region is cleaned with a soft stainless steel brush

• MOB 39 offers the best results of the non-activated fluxes tried at CERN. http://en.mbosolder.com/products,solder-gel.php

• Preferred soldering alloy: Sn 96.5% Ag 3.5%, Tm = 221 oC• Sn96.5Ag3.5 + MOB 39 is used for:

– Pretinning the NbTi and Nb3Sn cables– The actual Nb3Sn/NbTi splice

Feb 04, 2014J.C. Perez 8

Instrumentation & Quench heaters wires

Feb 04, 2014J.C. Perez 9

Instrumentation wires:

• AXON reference HH2619 LH• Conductor diameter 0.504 mm (0.15 mm2)• Conductor composition: Copper silver plated • External wire diameter: 0.95 mm• Wire insulation: polyimide tape wrapped (glued with a thin layer of fluoopolymer)• Nominal voltage : 1000V AC• Axon voltage test: (2*UN)+1000V= 3 kV• Approx. price: 2220 €/km

Quench heaters wires:

• AXON reference H 1619 L• Conductor diameter 1.5 mm (1.34 mm2)• Conductor composition: Copper silver plated • External wire diameter: 1.8 mm• Wire insulation: polyimide tape wrapped (glued with a thin layer of fluoropolymer)• Nominal voltage : 600V AC• Axon voltage test: (2*UN)+1000V= 2.2 kV• Approx. price: 4500 €/km

Updated status and possible plan1. 28/10-01/11, fabricate short plastic poles (BEND poles), 1 set2. 28/10-01/11, Wind/cure outer layer short Cu coil3. 28/10-01/11, Update BEND inner/outer layer spacers after short winding test4. 18-22/11, Update ROXIE/CAD inner/outer layer spacers5. 18-29/11, Fabrication inner/outer layer BEND/ROXIE plastic spacers (v3) for FNAL6. 02-06/12, Insulation of CERN Cu cable7. 9-13/12, Fabrication inner/outer layer ROXIE plastic spacers (v3) for CERN8. 06/01-17/01, Fabrication inner/outer layer ROXIE/BEND plastic spacers (v3) for LARP9. 06-31/01, LARP to wind 1st short coils (ROXIE LE/BEND RE) with plastic parts10. 13-31/01, CERN to wind 1 short coils (ROXIE) with plastic parts11. 10-14/02, Update ROXIE (v4)12. 03-14/02, LARP to wind 1sd short coils (ROXIE RE/BEND LE) with plastic parts13. 17-21/02, Update BEND (v4) and decision14. 16-19/12, Delivery 6 poles to FNAL15. 27-31/01, Delivery of 2 sets metal spacers (arrival 07/02/14) for CERN and FNAL16. 03-07/02, Launch procurement 1 set of metal spacers for FNAL17. 17-21/02, Launch procurement 5 sets of metal spacers for FNAL/CERN (market survey completed)18. 03-07/02, Launch the price inquiry for 3 sets of CERN poles19. 17-21/02, arrival of 2 sets of Cu wedges

29/01/2014P. Ferracin 10

CERN W&C tooling status

• All delivered and cleaned

• Next week assembly

29/01/2014P. Ferracin 11

CERN tooling status

• R&I tooling– Parts ordered

• Step files requested• Nb-Ti lead related parts on hold

– Expected in late March (1 reaction set) – end of April (the rest)

• CERN wedges– Expected by mid-March

• Work in progress to meet tolerances requirements

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Susana Izquierdo Bermudez

Field in Nb3Sn-Ti splice region

13

0 500 1000 15000

2

4

6

8

10

Field @ x = 75mm, y=0 mm, I = Inom = 17320 A

z (mm)

Fiel

d [T

]Magnetic Yoke & Pad =975 mmNon magnetic Pad =350 mm Non magnetic Pad = 225 mm

Susana Izquierdo Bermudez

• Field at the ends decay very quickly• The fringe field of the magnet is negligible compared with the self-field of the

interconnection

14

Field in Nb3Sn-Ti splice region

Problems can be decoupled Field in the interconnection can be computed analytically and/or with a very simple model

I (kA) Bp (T)(ANSYS*)

Bp (T)(ROXIE**)

17.3 1 1.3

21 1.2 1.6

“Recycling” a very simple model I did for the LHC main interconnections

* Does not consider iron and the rest of the leads** Does not account for current flow in between cables

Design Parameter for Nb-Ti lead:Bp = 2TCurrent distribution

Nb-Ti leads parameters (from Luc)

• Strand: 1.065 mm LHC strand, 1.6 Cu/SC ratio• Cable: 34 strands, width of 18.15 mm and a mid-thickness of 1.92

mm.• Field

– In the nominal conditions (17.5 kA) we expect a field in the splice area of ~1.5 T

– In the short sample condition (21.2 kA) we can say that the field in the splice area the field is ~2 T

• Critical current– Luc estimated approximately what would be the critical current of the cable

• 17 kA at 10 T and 1.9 K• as high as 60 kA at 2 T and 1.9 K (to be confirmed)• 44 kA at 2 T and 4.2 K • 39 kA at 3 T and 4.2 K

19/12/2013P. Ferracin 15

Comparison End Spacer Heat treatment

before after

before after

before after

before after

before after