1. WP3 Meeting – December the 10th 2015 H. Prin
Quadrupoles and orbit correctors bus bars routing along the inner triplet string
WP3 Meeting – December the 10th 2015
H. Prin

2. Outline Base line and Alternative schemes
Internal vs External routing Pros and Cons
Preliminary layout proposal
Comparison with existing situation in the LHC DS
Summary

3. Inputs Alternative scheme Base line
Ramp down of the inner triplet magnets - J.-P. Brunet
22nd HL-LHC TC –30 April 2015
Alternative scheme
Base line
Ramp down of the inner triplet magnets - J.-P. Brunet
22nd HL-LHC TC –30 April 2015
Follow up of powering schemes for IT, Q4 and D1/D2 - M. Fitterer
22nd HL-LHC TC –30 April 2015
Triplet circuit protection with heaters and CLIQ - E. Ravaioli
5th HiLumi LHC-LARP Annual Meeting, 28 October 2015

4. Base line scheme Total Total External bus bars Internal bus bars
Orbit Correctors
Trim Q1
Trim Q2b
Q1 – Q3
CLIQ
Q2a-Q2b
External bus bars 6 16 4 2
Total 1 2 1 3 8 1 4 1 1 2 2 8
Splices 50 2 5 16 2 3 22
Spliced on surface
Spliced in the tunnel
Internal bus bars 11 +5 9 +3 32
+16 2 30
+14
Total 1 2 1 2 3 8 6 2 8 1 6 2 8 2 8
+43
Splices 2 21 93 5 21 22 22

5. Alternative scheme Total Total External bus bars Internal bus bars
Orbit Correctors
Trim Q1
Trim Q2b
Main Quads
CLIQ
External bus bars 1 7 16 6 2
Total 1 2 1 1 8 4 1 1 2 2 8 3
Splices 2 5 14 3 48 3 21
Additional trim on Q3 or Q2A could be installed on the warm par without further bus bar
Orbit Correctors
Trim Q1
Trim Q2b
Main Quads
CLIQ
Internal bus bars 1 10 +3 32
+16 12 +6 4 +2 28
+12 1 2 1 2 8 3 1 6
Total 2 8 4 2 8 3 2 8 3
+39
Splices 2 5 18 20 21 21 87

6. Int./Ext. routing Pros and Cons
External bus bars
Internal bus bars
Development
Bus bars / cables
Bus bars (Cables?)
Splice quantity 
 > 80%
Short to ground on a circuit or electrical fault
Cable exchange between the DFX and concerned interconnect 
Cryoassembly exchange
Possibility to alternate the impedances on the main circuit: Q2a and b on the return bus bar
 Not really needed according to Felix
Magnet exchange
Example for the alternate scheme
Q3 exchange:
Q2b exchange:
Q2a exchange:
 3 to 5 ICs to open
 Less splices to be redone
Or  only affected buses
20 splices or 5 disconnected/41 reconnected
18 splices or 17 disconnected/38 reconnected
12 splices or 19 disconnected/23 reconnected
 2 ICs to open
 All splices to be
de-soldered/re-soldered
41 splices
38 splices
23 splices
Interchangeability
Q1Q3 and Q2AQ2B
 Q1 and Q2a have to house all circuit present in respectively Q3 and Q2b to allow
 Plugs or  restrictions between the external line and the cold mass volume
Flexibility for cold test (Q1)
 Possibility to test each MQXA individually
 Additional bus bar needed to power each MQXA individually
(48 to 50)
(87 to 93)

7. Ext. routing preliminary layout proposal
Worst condition:
(without considering cables for D1 and CP)
Free section 47.9 cm2 2
2/1/0 8
2/3
Orbit Correctors
Trim Q1
Trim Q2b
Q1 – Q3
CLIQ
Q2a-Q2b
To be developed:
34 NbTi strands Ø1.065 mm
Cu/Sc ratio = 1.6
34 Cu OFE strands Ø1.065 mm
17kA or
34 NbTi strands Ø1.065 mm
Cu Stabiliser equivalent cross section
4kA
Present LHC 6kA cable:
13 NbTi wires Ø0.87 mm
Cu/Sc ratio = 1.36
7 Cu wires Ø0.96 mm
2kA
?kA
Present LHC 1kA cable:
1 NbTi/Cu wires Ø1.6 mm

8. Extracted from Delio’s talk on December the 3rd 2015
Ext. routing preliminary layout proposal
Preferred locations from the cold mass point of view taking into account interconnections, standardization, spare policy and ergonomics :
bus bar line in the cryostat in the vertical symmetry plane
bus bar entrance in the cold mass in the vertical symmetry plane on top
Heat exchangers on the bottom apertures of the magnets
Extracted from Delio’s talk on December the 3rd 2015

9. Present situation in the LHC DS N-Line
Bus Bar line for the HL-LHC triplet
(scaled) ? ?
A wires
3 – 6kA cables
N-Line cable partial extraction between 2 MBs
See Procedures: LHC-QBBI-IP-0030, 31 and 32 used during LS1 for MB exchanges

10. Summary Base line and alternative schemes studies shows: Open issues:
Up to 22 buses to be housed (only for the quads and the orbit correctors, CP and D1 to be added and integrated in between Q3 and DFX).
Using an external routing saves up to 40% splices, simplify consolidation in case of short and simplify the standardization in between Q1-Q3 and Q2A-Q2B.
Using cable rather than copper stabiliser soldered to Rutherford cable eases the expansion lyres design and integration.
Alternate scheme is a bit less consuming in terms of bus, current leads and splices.
One 2kA current lead for Q1 trim can be saved connecting it one warm side (no additional current lead in the alternative scheme for a Q3 or Q2A trim if required).
Open issues:
17kA cable or bus bar profile has to be developed (cohesion in between SC and Cu wires or expansion lyres to be addressed).
Cable for CLIQ depending on peak current intensity and time.
New splices types configuration and tooling.
Global interconnection integration on track, cryogenic requirements missing.
Interconnection and integration is a challenge on which we are working hard to find solutions.

12. Spare slides

13. Present LHC SC cables specifications

14. Triplet flow diagram