Status and Prospects of SPS Magnet Consolidation Program

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SPS Beam Lines In the Way to the LHC

Status and Prospects of SPS Magnet Consolidation Program

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Outline

Prospects for 2009… 2010

Impact of non shutdown 2009 – 2010Conclusion

Main magnets– Erosion

– Fatigue

– Statistics 2008 – 2009

Auxiliary magnets and equipment– Magnets

– Equipment

Introduction

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Outline

IntroductionAuxiliary magnets and equipment

– Magnets

– Equipment


– Fatigue


Prospects for 2009… 2010Impact of non shutdown 2009 – 2010Conclusion

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Introduction - Magnets in the Way to the LHC

MBB

MBI

MDH/M

DV

LS/L

SN

LO/L

ON

LOE/L

OEN

QFA/Q

DA

MPLH

MPSV

LQS

MPSH

QM

SBHC

MPLV

MDCV

MPNH

MBB-B

T/MBE

QFS

HB2

MDSH

MDSV

QTR

0

50

100

150

200

250

300

350

400

total spares

installed outside LHC way

installed on LHC way

Main magnets, continuous refurbishment program

Large families

New magnets in injection lines TI2/8, spares available

Critical since large families with few spares, but magnets are quite reliable

Courtesy of D. Smekens

January 2008: ‘MTTR and Spare Policy for SPS Magnets’ has been adressed by D. Smekens to ATC-ABOC days

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Introduction

Reminder of the conclusions: – No specific risks for auxiliary magnets: generally small families of

magnets with spares available for most of them

– Main magnets are top priority since they constitute the largest families with few spares, and have a high risk of breakdown due to important solicitations (operated at saturation, high water flow speeds, no valves…)

need close monitoring of performance and early detection of possible accumulation of breakdowns that could be forerunner of illness (e.g. water leaks erosion)

Main scope of this presentation will be the main magnets

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Outline


– Magnets

– Equipment


– Fatigue



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Several issues in auxiliary magnets could perturb the operation of the LHC: – Few spares are available for several magnet families most of which are mandatory

for the LHC operation (MPLV, MPSV, LS/LSN, LO/LON, B340…)

– Large majority of the spare magnets are not tested could increase MTTR if there is a magnet failure

– Use of spare magnets for new projects (e.g. HiRadMat) could lead to a significant decrease of available spares for some families (MDSV, MBS)

– Many of transfer line quadrupoles (QTL, QTA, QNL) have degraded shimming that can generate coil movements low reliability (water leaks, short-circuits to ground), but many spares are available from WEA

However, inspections led on the auxiliary magnets at the beginning of this shutdown have shown no major reliability issue

Our goal is now to have at least 1 operational spare (tested) for each magnet type ASAP

Auxiliary Magnets

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Breakdowns of ancillary equipment that could also impact on accelerator operation:– Degradation of water hoses in use for more than 12 years

need to be replaced (≈10 Km of hoses, ≈5000 fittings) to be done (TE/MSC)

– Flashover between busbars

need inspection and cleaning To be completed at the same time as water hoses replacement (TE/MSC)

– Failure of water cooled cables (no spares installed, no spares available at the moment)

investigations of risks of erosion inside cooling ducts inside cables in progress (collaboration TE/MSC – EN/EL)

– Reliability issues of installation vehicles used for main magnets

need complete refurbishment and upgrade for future projects in progress by EN/HE

Risk score to suffer such an event can be kept very low if appropriate actions are undertaken / pursued

Auxiliary Equipments

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Outline


– Magnets

– Equipment


– Fatigue



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Usual issues are linked to ageing which is translated in erosion and fatigue phenomenon's

ErosionIn places where high flow speed crosses sharp transitions

effect is critical in thin copper tubes: water leaks

– In dipoles:

• Lintott coils (2/3 of MBB’s): due to design of the coil, flow reaches 9 m/s in some places. Consolidation

program achieved over the 3 last shutdowns to replace all manifolds by improved design:

255 magnets in the machine equipped with these coils + all spares (even with Alsthom coils) have been

refurbished

Main Magnets – Erosion Issues

Original design New design

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• Alsthom coils (1/3 of MBB’s + all MBA’s): erosion induced water leaks also occur in these coils, but at

a much lower rate than in Lintott coils. Also, leaks are generally located in non conform manifolds in

which the section has been thinned or deformed by a bump (generation of higher flow speed and

turbulences) or in which the wall thickness has been decreased by grinding

Inspection during this shutdown has shown non conform manifolds on 24 magnets: deformed parts of

tubes have been replaced to lower the risk of leaks. However, a consolidation (upgrade) like Lintott’s

should be necessary sooner or later


Grinded tube

Bumps

Tube partially replaced

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Erosion cratersWater leak

– In quadrupoles: 1 erosion induced water leak occurred at the end of run 2008.

Phenomenon is currently being studied. Recent endoscopies have already shown it is not a generalized problem, but quite extended. Following results, a consolidation could be necessary soon (next shutdown ?). A solution consisting in the replacement of all thin tubes could be implemented in 1 shutdown in situ.

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FatigueDue to tens of million of pulses accumulated over 35 years of operation

(although SPS initially designed for 50,000 h !)

effect translates in different manners among the magnet families:

– In dipoles:

• Break of the fastening screws of the magnetic correction pole shim : phenomenon discovered this shutdown during inspection under magnet patrol access mode (main magnets pulsed). Currently being studied with help of EN/MME/MM

Main Magnets – Fatigue Issues

2 pole shim sets at each end of dipoles

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Spring pins

M8 cylindrical head screws, steel class 12.9

Pole shim system designed to adjust the magnetic length to match it with a reference magnet by adding lamination on pole ends (reproducibility of integrated field)


1 to 10 laminations added (th.1.5mm)

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In total, 26 pole shims were found defective on 18 magnets (16 MBB’s and 2 MBA’s)

Possible causes:

non conform mounting (unadapted screw length or tightening torque)

high number of occurences could be due to accumulation over last 2 or 3 years (not detected during previous inspections ?) to be checked with results of future inspections

sollicitations of run 2008 were more intense, with return of pulses at 450 GeV/C. Indeed, previous occurrences were already encountered during operation at 450 GeV/c between 1980 and 2000.


Head of fastening screw and spring pin broken

Magnetic correction laminations falling apart Pole shim moving away from its position

Broken head of screw trimming into the vacuum chamber and the coil insulation at each pulse

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Consequences:

degradation of the magnetic field quality of the magnets during operation (some shims were found on the ground)

degradation of the coil insulation leading to short-circuits to ground (1 case found during HV test): the end shim displaced diagonally trims into the insulation of the coil

Strategy to consolidate:

1st step: repairing of the broken pole shims found this shutdown before the SPS restart in march

Only 40% could be repaired in a corresponding way (i.e. with new screws and pins)

For the 60% remaining, impossible to remove both screws in situ laminations and end shim had to be glued. In addition, dismountable external fastening devices are being manufactured to allow keeping the pole shims in place up to next shutdown ( consolidation)

2nd step: analysis of the phenomenon to define if upgrade of the system is needed

Analysis of broken screws collected (EN/MME/MM) in progress

Computations of a model + tests in laboratory to be done during run 2009


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3rd step: implementation in situ of solution based on results of study If no or small upgrade is required, replacement of the screws (≈6000 units) with

appropriate mounting by screws of same size (other steel quality could be chosen)

If upgrade is required, need to develop adapted tools to allow modifications (M8 M10) in situ (few space available)

In both cases, has to be done (or at least started) during next shutdown


MBB isometric view – connection side

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Main Magnets – Fatigue Issues• Longitudinal displacement of coil inside the yoke: phenomenon discovered on 5

dipoles (3 MBA’s, 2 MBB’s) during this shutdown inspection. Coils are shifted up to 40 mm towards connection side, in some cases pushing the vacuum chamber of the dipole upstream.

Possible causes: accumulation of movements over the years (never detected before because amplitude of movement was too small?) ; degradation of soft shimming ; kapton foil wrapped between coil and yoke decrease friction coefficient ; pulses at 450 GeV/C ?

Disassembly of the magnets (run 2009) will produce more information

Vacuum chamber trimming into the coil insulation

Coil shifted of 30 mm w.r.t. nominal position

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Main Magnets – Fatigue IssuesConsequences: degradation of the magnetic field quality of the magnets during operation (corrections done by BE/OP last run seem to coroborate this fact), degradation of the coil insulation leading to short-circuits to ground

Actions:

- All magnets with this problem have been replaced

- Measurement campaign of longitudinal position of all coils is being completed

- Adapted coil retainers could be designed during next run and put in place during next shutdown (e.g. Vetronite blocs put down on the magnet feet)

Coil retainer installed in the machine (Vetronit

plate and blocks)

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– In quadrupoles (QD/QF) and enlarged quadrupoles (QFA/QDA):

• Coil movements: due to degradation of soft shimming between coil and yoke (radiation, temperature, hardening). Result in fatigue of the copper tubes and brazed junctions of the manifolds water leaks

Corrective action for QD/QF: preventive exchanges (average of 3 / shutdown) and continuous refurbishment activity in adapted facility in radioactive workshop b.867

Corrective action for QDA/QFA: shimming in situ with Vetronite pieces glued with Araldite since no reconstruction facility / procedure are available at the moment. 3 spare magnets are available (1 fully operational) for 14 magnets operated


SPS Main quadrupole SPS Main enlarged quadrupole

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Statistics Main Magnets 2008 - 2009 Results: 5 interventions during run period, 15 magnet exchanges during

shutdown period (3 for vacuum chamber coating project SPSU)Période Position # série Type de panne / dysfonctionnement Action

Run 12370 MA104 Fuite d'eau manifold Réparation définitiveRun 40150 MB065 Fuite d'eau manifold Réparation définitiveRun 12530 MB188 Beam crash - fuite de vide Remplacement correctifRun 11090 MB306 Fuite d'eau manifold Lintott (prévu dans programm consolidation 2009) Réparation temporaireRun 62810 Q037 Fuite d'eau manifold Réparation définitive

Shutdown 11590 MA180 Bobine & CV décalées longitudinalement + contact bobine - CV Remplacement correctifShutdown 52230 MA252 bobine décalée longitudinalement 40 mm Remplacement correctifShutdown 63570 MA259 Bobine & CV décalées longitudinalement + contact bobine - CV Remplacement correctifShutdown 10990 MA358 Fuite de vide Remplacement correctifShutdown 51490 MB013 Installation aimant avec coating chambre à vide Projet SPS upgradeShutdown 51550 MB015 Installation aimant avec coating chambre à vide Projet SPS upgradeShutdown 53490 MB044 Shims de correction magnétique cassée + CC bobine culasse (HV test) Remplacement correctifShutdown 32930 MB062 Fuite de vide (endommagé lors de la consolidation manifold 2009) Remplacement correctifShutdown 30930 MB121 Point chaud radiation 40 mSv interconnexion upstream Remplacement correctifShutdown 51530 MB282 Installation aimant avec coating chambre à vide Projet SPS upgradeShutdown 63550 MB356 Bobine & CV décalées longitudinalement + contact bobine - CV Remplacement correctifShutdown 63350 MB374 Bobine & CV décalées longitudinalement + contact bobine - CV Remplacement correctifShutdown 13410 Q093 Mouvement bobines - shimming dégradé + fuite d'eau manifold Remplacement correctifShutdown 42410 Q148 Mouvement bobines - shimming dégradé Remplacement préventifShutdown 52210 Q159 Mouvement bobines - shimming dégradé Remplacement préventif

Damage type 2008-2009 Average of last 4 years Conclusions

Dipole

Vacuum leak 3 (1 due to shock, 1 due to beam) 0.25 Only 1 relevant. Statistic too rare, wait for new occurences

Short-circuit 1 (induced by pole shim) 1.25 Stable

Water leak 3 (1 forseen in consolidation) 2.5 Stable, should decrease next year with consolidation

Pole shims screws 26 (on 18 magnets) No data (not detected ?) To be monitored in the future

Longitudinal displacement of coil 5 No data (not detected ?) To be monitored in the future

QuadrupolesWater leaks 2 0 Study phenomenon and prepare complete refurbishment

Preventive exchange 3 2.5 Stable (rhythm also linked to amount of spare available)

Interventions run 2008 & magnet exchanges shutdown 2009 on main magnets

Breakdown statistics run 2008 – shutdown 2009 on main magnets

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Outline


– Magnets

– Equipment


– Fatigue

– Statistics 2008 - 2009


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Refurbishment of all spare main magnets (taken out of the machine + in storage) during next shutdown, to be ready if we should encounter drastic reliability issues (pole shims on dipoles, waterleaks in quadrupoles…)

Prepare at least 1 spare magnet fully operational for each magnet type, starting by highest risk scores = f (impact on LHC and other facilities, ratio number of magnets in operation to number of spares, reliability)

Design and prepare implementation of pole shim consolidation + coil retainers

Prepare manifold consolidation of quadrupoles

Prepare a global replacement campaign of the rubber water hoses in the whole SPS complex

If resources available, restart QTL/QTA refurbishment program

Prospects for 2009… 2010

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Outline


– Magnets

– Equipment


– Fatigue



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Program of magnet maintenance mainly based on results of general inspection performed in magnet patrol access mode at the beginning of the shutdown gives a complete overview of the state of magnets, allows early detection of illnesses and leads to preventive and corrective actions on the magnets (exchanges, modifications, upgrades…)

Scenario with no shutdown seems unrealistic, moreover with an operation at 450GeV/c which makes more demands on the magnets could decrease drastically the reliability of the machine without any signs (if no inspections)

Considering a scenario with a shortened shutdown (2 weeks of effective work), the following actions would be mandatory to ensure a quite reliable operation of the magnets in the SPS complex as LHC injector (i.e. except TDC2 and NEA):

– High tension test on the main magnet system (magnets, busbars, water-cooled cables) in collaboration with TE/EPC + test of the imbalanced current detector: ½ day, machine closed ;

– Inspection of the main magnets in the ring (access mode ‘magnet patrol’) + magnets in the transfer lines (mainly QTL’s in TT40 and TT60): 3 days (1 to open the covers, 1 for the inspection (machine closed), 1 to close the covers)

– Exchange (not preventive, only corrective) or repairing of the defective magnets (pole shim screws broken, water leaks, short-circuits detected with the HV test…): approximately 1 day / magnet, following the type of defect ;

Therefore, main impact would be that neither preventive exchanges of magnets nor programs explained before (consolidation of pole shims, replacement of water hoses…) would be possible risk to decrease reliability

Impact of non shutdown 2009-2010

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Outline


– Magnets

– Equipment


– Fatigue



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Recent findings confirm what we already know: the SPS main magnets suffer ageing issues, and need maintaining if one wants to operate this machine for some additional decades with the LHC

Careful monitoring of the magnet performance by frequent inspections is the only way to avoid suffering drastic reliability issues. With ~1000 units over 2200 in the way to the LHC, they are the keystones of the SPS link in the injector chain

Consolidation of pole shims and quadrupole manifold refurbishment have to be done soon to ensure reliable operation

We strongly recommend to have at least one short shutdown to perform careful inspections

Conclusions

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MTTR & Spare Policy for the LHC Injectors & Exp. Areas, David Smekens

Report to the PAF WG on the Status of the Magnets in the Existing Accelerators, W. Kalbreier, S. Ramberger, D. Smekens, T. Zickler, K. H. Mess

SPS Main Dipole Exchanges in 2007 & Next Shutdown Work, J. Bauche, W. Kalbreier, D. Smekens

New Strategy for the Repair of SPS Dipole Water Manifolds, J. Bauche, S. Cettour Cavé, W. Kalbreier, D. Smekens (EDMS Doc. No.: 783313)

References

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Annex 1: Overview of the Complex SPS as LHC Injector

SPS Bending Peak Field: 2.02 T @ 5750 A (450GeV/c)

SPS as LHC injector incorporate:

TT10 Beam Transport Tunnel from PS extraction (TT2) to SPS Injection point in Sextant 1

SPS Main Ring

TT40/TI8 injection tunnel;

TT60/TI2 injection tunnel;

13500 m of beam line

2200 magnetic elements on LHC way

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Annex 2: Fatigue Phenomenon - Wöhler Diagram

Documents

Status and Prospects of SPS Magnet Consolidation Program