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Shortening the long RQF/RQD busbar segments in points 1 and 5

Presented by Sandrine Le Naour

with the helpful collaboration of TE-MSC-LMF

12 Nov. 2012Third LHC Splice Review

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Present situation on RQF/D bus segments

Technical solution

Quality control

Time estimation

Conclusion

12 Nov. 2012Third LHC Splice Review

Outline

RQF/D bus segments in point 1 and 5 In the arc, most of MQ busbar segments contain 8 splices (go

through 6 dipoles + 2 quadrupoles, ~107m)

In point 1 and 5 , long bus segments (> 400m long) connect the main quads Q12 to Q11 via 32 splices.

These bus segments go from Q11 to the Q7 and return in the DFBA shuffling module to Q12 (Q10, Q9, Q8, Q7 are MQM magnets and are individually powered in point 1 and 5)

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RQF/D bus segments in point 1 and 5

Bus segment magnet1 <-> magnet2 Rmax (nΩ) rangDCQDQ.11L5.L MQ.12L5.B2 <-> MQ.11L5.B1 2.86 2DCQDQ.11L1.L MQ.12L1.B2 <-> MQ.11L1.B1 2.37 4DCQFQ.11L1.R MQ.12L1.B1 <-> MQ.11L1.B2 1.52 14DCQDE.11R5.L MQ.12R5.B1 <-> MQ.11R5.B2 1.37 20DCQFQ.11L5.R MQ.12L5.B1 <-> MQ.11L5.B2 0.63 173DCQDE.11R1.R MQ.12R1.B1 <-> MQ.11R1.B2 0.34 382DCQFE.11R1.L MQ.12R1.B2 <-> MQ.11R1.B1 0.31 411DCQFE.11R5.R MQ.12R5.B2 <-> MQ.11R5.B1 -0.02 709

In LHC, 8 MQ segments contain 32 splices (RQF/RQD, R side, L side, point 1 and 5)

For these segments, if we consider 31 correct splices (with a resistance of 0.3n )W , the Max Resistance of one of the splices is

Rmax = Rsegment-(n-1)*Rsplice

For LS1, we suggest at the moment to redo completely all splices in a RQ segment if Rmax > 2n . W (Threshold is 0.82 n W for dipole segments)

With this criteria 102 splices in RQ lines will be de-soldered and re-soldered and the 2 first segments concern already 64 splices!

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RQF/D bus segments in point 1 and 5 We propose to shorten the RQ bus segment after the magnet

Q11. The segments will be only 50m long (instead of 400m long),

easier to protect Only 6 splices in the segment (instead of 32) 13 interconnections in RQ lines do not need to be open,

reinforced and qualified ( that concern 208 splices which 52 must be completely redone – 104 sleeves not opened)

No change on instrumentation (only soft parameters for QPS) … But the MQ line will be cut after the connection cryostat

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RQF/D bus segments in point 1 and 5

Better to not leave active bus lines where they are not needed

No Impact for HL-LHC

At the moment, no project is retained to power additionnal magnet(s) on RQF/RQD circuits (BE-ABP is informed).

No Electromagnetic Impact:

M1 and M2 are no more actived between MB11 and Q7 (only M3 stays) negligeable effect (S. Russenschuck)

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LHC configuration : Room available L side

R side

Connection Cryostat Bellow zone Sleeve zone Quadrupole

L=217mm, D=80mm L=207mm, D=100mm Quadrupole Bellow zone Sleeve zone Connection Cryostat

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Proposed solution Direct U turnTo connect properly the 2 splices, the 2 bus bars are twisted by 90deg. and a superconducting cable covers the 2 cables of the interconnection.

The assembly is then stabilized with a massive copper piece.

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The twisting of the busbar doesn’t damage the SC filaments. The performance of the busbar out of magnetic field ≥ 40kA ! 12 Nov. 2012Third LHC Splice Review

A first prototype

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Quality Control : Gamma Ray

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Nice connection shown by g-ray radiography. From busbar to busbar via the central piece (act as a shunt) and along the SC cables.

As only 8 such connections will be done in 2 points, a gamma-ray inspection will be performed systematically.

Spool piece lines will be open for a better access to the main busbar, but it is also a request from ElQA for the qualification of each individual line (spool piece + spare) during the progress of the train.

Thanks to EM-MME-MM for the radiographies 12 Nov. 2012Third LHC Splice Review

Quality control : Electrical test

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A QC report is written on the 2 first prototypes : EDMS 1240171

Similarly to R8/R16 qualification at room temperature, R5 and R3 resistance measurements will be performed:

R5 from busbar to central pieceR5 expected value ≤ 6 µΩ

R3 from busbar A to busbar B at the level of the shunt (green points)R3 expected value ≤ 4 µΩ

Thanks to TE-MSC-SCD

A

B

8.3 ± 0.1

11.0 µΩ ± 0.1

unsoldered shunt

Test 1 : unsoldered shunt

Test 2 : soldered shunt

12 Nov. 2012Third LHC Splice Review

Insulation of the connection

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The cut busbars will be included inthe insulation box and one leg will be connected to ground.

The insulation box will be similar to the one for the quad connection, with a comb piece for the spool piece.Eccobond bag will be also included

Hydraulic section still sufficient for helium circulation (A. Perin)

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Time estimation

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Time gain for the train (normal teams) : 5-6 days

Time to implement the new connection in Q11 (train special team): 1day/circuit = 8 days

Time estimated to change flanges (SIT) : 4 days

Time estimated to reconnect of spool pieces lines (SIT + ElQA) : 2 days

Gamma ray : 2 or 4 nights

- 6 days

+8 days

+4 days

-2 + 2 days

0 days

+6 days but with new

flanges !

12 Nov. 2012Third LHC Splice Review

Conclusion 1/2

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We propose to shorten the long RQ busbar segments which connect Q11 to Q12 in points 1 and 5.

Reduce them to 50m long and 6 splices instead of 400m long and 32 splices. Deactivation of over-length busbars.

In 4 sectors, 13 interconnections (M1 and M2) don’t need to be open, reinforced, qualified… (it concerns 208 splices which 52 must be re-soldered because of Rmax criteria at cold).

So the risk to damage spool pieces busbar is reduced.

No impact for the HL-LHC project.

Despite a small volume available for a special connection, the direct U turn is an easy configuration to implement.

Gain of time for the regular teams but additional work for the special teams (One of the train + SIT).

The cost is negligeable.12 Nov. 2012Third LHC Splice Review

Conclusion 2/2

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This project was presented to the splice task force, TE departement technical meeting (TE-TM) and the LHC Machine Committee (LMC). All teams support the project.

Next steps Training on the mockup for a last adaptation of the tooling and

insulation

Test at cold.

Thermal choc in N2,liq done successfully

Test at 4.2K to be performed

Documentation (ECR)

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Thank you

LHC Bus Bar Max Splice Resistances, 2010-2012

Normal: 99.7%=532pΩ (53)

L-L: 99.7%=801pΩ (10)

Normal: 99.7%=1.17nΩ(30)

L-L: 99.7%=2.15nΩ (7)

27 splices

38 splices+ 2*32

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Conclusion:-Measurement error on 700 rumps statistics is about 100±25pΩ for RB and RQ;- Relatively good 3 params fit found for both circuits;- 3σ is 0.8nΩ for RB circuit and 2.1nΩ for RQ circuits;- It gives about 27 + 38 = 64 splices to be redone if will be applied as a safe criteria;

Reversibility

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If M1 and M2 lines must be reactivated for a future project (hypothesis), it is considered up to now that the empty cryostat will be changed (for a new dimension, for example) and then reconfigured for a possible connection with the Q11 magnet.If a “quick re-connection” must put in place ( but13 interconnections are not consolidated), the superconducting cable can be kept, copper stabilizer removed on 40-50 mm to gain cable flexibility. The SC cable will be attached to the insulation box.

Additionnal time estimated : 1 day per circuit. 12 Nov. 2012Third LHC Splice Review

Still to do

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If the project is accepted

Finalise the design of the shortcut (in progress) Tooling (in progress) Design of the insulation of shortcut and insulation of the

desactivated busbar (left floatting). Put the shortcut in place on a interconnection mockup A method to qualify the shorcut (eqv R8-R16) Estimate the hydraulic diameter Do a cold test for the final solution (Still to define). …

12 Nov. 2012Third LHC Splice Review

Busbar segments of Main quad circuits at odd points

x=3, 7

x=1,5

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Estimation of electromagnetic forces

21 Calculated by Susana Izquierdo Bermudez

12 Nov. 2012Third LHC Splice Review