e-xfel module completion and repair activities x-ray free … · 2016. 7. 5. · xfel cryomodule...

XFELX-Ray Free-Elect ron LaserE-XFEL Module Completion and Repair Activities

O. Napoly, CEA-Saclay, Irfu/SACM

5 July 2016 TTC Meeting, Saclay 1

XFELX-Ray Free-Elect ron LaserOutline

• Cryomodule production status

• Module performance vs. Clean Room procedures

• Module repair activities

• Conclusions


XFELX-Ray Free-Elect ron Laser

E-XFEL Cold Linac 17.5 GeV

1 + 100 accelerator modules

808 accelerating cavities

1.3 GHz / 23.6 MV/m / 1010

25 RF stations

5.2 MW each



CEA deliverable to European XFEL:

assembly of 103 accelerator modules

on the Saclay site and with CEA* infrastructure * nine pumping systems (with mass-spectrometer) and one laser-tracker from DESY

* two tuner control racks from INFN

Workforce by an industrial contractor Alsyom:

Quantity production goal: 1 module / week

Quality performance goal: Eacc > 23,6 MV/m

Cryomodule Production



the XFEL Village

Module integration route

Coupler Area CO-WS1

Alignment Area AL-WS1 & 2

Shipment

Area

SH-WS1 &

CO-WS2

Roll-out

Area

RO-WS1 & 2 Warehouse

Clean room

Area

CC-WS1 & 2

SA-WS1 & 2

Cantilever Area CA-WS1

Assembly Hall : Workstations


XFELX-Ray Free-Elect ron LaserCryomodule Delivery


2016:

25 modules

Figure: delivery of cryomodules, from XM1 to XM100

• 100 modules delivered to DESY so far (incling XM-3, XM-2, XM-1).

• In 2015, one cryomodule was delivered every 4 days, 52 in total.

• The Cold Linac includes also two pre-series cryomodules: XM-2 and XM-1

• The shipment of XM100 is scheduled in 27 July 2016

2015:

52 modules

2014:

24 modules

XM-3 XM-2

XFELX-Ray Free-Elect ron LaserModule Tunnel Installation: 1+83 modules


Seven modules need(ed) repair: XM8, XM22, XM24, XM46,

XM50, XM54, XM91

XM29

XFELX-Ray Free-Elect ron LaserProduction Throughput


• 5 day throughput was reached mid-October 2014 with XM15

the design of the Assembly Infrastructure was sound

• 4-day throughput was reached in January 2015 with XM25

Courtesy

June 2016: XM95

March 2014: XM1

XFELX-Ray Free-Elect ron LaserThroughput at Cold Coupler WS


Courtesy

days

Cold coupler assembly


Throughput at String Assembly WS


Courtesy

days

String assembly


Throughput at Roll-Out WS


Courtesy

da

ys

d

ays

Cantilever Warm coupler assembly

Alignment Roll-out

XFELX-Ray Free-Elect ron LaserImproving Integration Processes


Acceleration and Quality of Production benefited mostly from:

• New clean room assembly procedure: moving individual cavity venting

after the leak check of the cold coupler assembly, rather than later,

before the string assembly. This eliminates one connection to pumping

stations for cavity venting, and one valve closing-opening cycle.

• New equipment, e.g. string leak test plexi-box:

• Pure Argon gas for Titanium welding, instead of He-Ar (50%-50%),

to avoid the long and unpredictable time to pump and purge the LHe

tank to reach the He background for the leak test (LT) by external

accumulation.

• Reducing the impact of non-conformities, particularly imported NC.

More human resources have been put on incoming inspection and QC.

XFELX-Ray Free-Elect ron LaserQuality Control: Non Conformities

Non Conformities recorded by Alsyom fall into 3 categories:

1) Tooling and equipment (TOOLING), responsibility by CEA/DESY

2) Accelerator components (PRODUCT), responsiblity by suppliers

3) Assembly operations (PROCESS), responsibility Alsyom

The number of PRODUCT Non-Conformities has not gone down.

But, with better and more efficient detection at incoming inspection, the

impact of PRODUCT NC on the module assembly has considerably

decreased, compared to when many NC were discovered ‘on the fly’.


XFELX-Ray Free-Elect ron LaserQuality Control

The Quality Control of QC is needed !


Quadrupole Unit Transport:

QC by Alsyom

Quadrupole Unit Transport:

QC by DESY

XFELX-Ray Free-Elect ron LaserCryomodule Performance at AMTF

• AMTF average gradient is 18% above specs : Eacc = 27.9 MV/m.

• All but 5 of 98 tested modules are on XFEL specs (23.6 MV/m):

• XM33, XM58 and XM68 are limited by individual cavity performance

• XM45 was impacted by a clean room power outage

• XM46 was impacted by beam vacuum leaks


Average operating gradient per cryomodule, clipping the VT results to 31 MV/m

XFELX-Ray Free-Elect ron LaserXM68 Performance


Cavity 3: Q0 < 1010 in AMTF test (who knows ?)

Cavity 8: field emission has disappeared in AMTF.

It is not an isolated case !

Cavity field emission Quench Limit

Operating Gradient

CAV8

VT @ 31 MV/m

MT @ 31 MV/m

VT @ 20 MV/m

XFELX-Ray Free-Elect ron LaserCryomodule Performance : XM45


XM45 string assembly was interrupted by an accidental power outage

with operators leaving the clean room for safety reasons, while a string of

3 cavities was under N2-flushing.

We have no good explanation for cavity 4 and 8 gradient degradations.

Eacc = 22,8 MV/m

XFELX-Ray Free-Elect ron LaserCryomodule Performance : XM46


XM46 string was leaky in the clean room AND before shipment. Both

leaks have been repaired at Saclay but they generated 3 extra connections

of the beam vacuum to pumping groups, and 2 additional venting-pumping

Eacc = 19,7 MV/m

XFELX-Ray Free-Elect ron LaserCryomodule Performance at AMTF

• Red bars include 97 modules (776 cavities): 47% of the cavities are power limited at 31 MV/m.

• Blue bars include only the last 43 modules (344 cavities) with simplified clean room procedures:

59% of the cavities are power limited at 31 MV/m.

• This is the optimistic-bias view of the ‘half-full glass’, combining good cavity production and

good module assembly.



Cavities 2,4, 6 and 8 have higher field emission

in VT (@quench limit gradient) than in AMTF

(@ 31 MV/m power limit).

24 5 July 2016 TTC Meeting, Saclay


Operating Gradient

MT @ 31 MV/m

VT @ 34-38 MV/m




Operating Gradient

MT @ 31 MV/m

VT @ 32-38 MV/m

• Cavities 5,6,8 warm coupler parts were

exchanged at DESY after to coupler over-

heating during TEST01.

• The lower performance of cavity 5 at TEST02

can be caused by the cavity venting needed

for the coupler repair operation.

XFELX-Ray Free-Elect ron LaserAbout Gradient Comparison

• Accelerating gradients are the most scrutinized module performance

parameters, although heat loads, alignment and PED certification are

entering the acceptance criteria.

• The absolute gradient is the result of the whole production chain,

from the Nb sheet to the module test (MT). It is mostly determined by

cavity manufacturing and module assembly.

• The quality of module assembly shows in the gradient difference

between cavity acceptance (VT) and module acceptance (MT).

• The VT vs. MT comparison of both the ‘maximum’ and the

‘operational’ gradients is impaired by a systematic error:

1. Maximum gradients depend on 1) RF duty cycle, 2) cooling conditions and,

3) magnetic environment, which are completely different from VT to MT

mostly cavity-independent error

2. Operational gradients depend, in addition, on X-Ray measurement

devices which are different from VT to MT (although cross-calibrated)

mostly cavity-independent error

3. Finally, Q0 is not measured in MT: therefore the MT usable gradient could

correspond to lower or higher Q0 values cavity-dependent error


XFELX-Ray Free-Elect ron LaserCryomodule Performance: VT vs. MT

• Significant gradient degradation from XM6 to XM23, while CEA and Alsyom put all their effort

in achieving production goal of 1 CM/week: an audit of string and module assembly was

conducted by CEA on XM26

• A simplification of the clean room procedures was introduced at XM54: no degradation after


1st sample of 34 series CM

Eop = -2.1 MV/m

2nd sample of 19 series CM

Eop = -1.7 (-0.9) MV/m

last 42 series CM

Eop =+0.4 MV/m

CEA Audit New clean

room procedure

XFELX-Ray Free-Elect ron LaserXM26 Clean Room Assembly Audit

Audit Findings:

• Operators walk too fast in the clean room.

• Record the cleanliness level (< 10 particles / min) reached on the

angle valve before the pump connections to the cavity (CC and SA).

• Two operators are requested to connect cavity to the pumping

system (CC and SA).

• Two operators are requested to position inter-cavity bellows and

screw first 4 studs (SA).

• Pre-alignment of parts (coupler and cavity flanges at CC, inter-cavity

bellow/cavity-coupler-side flange at SA) is requested for easy and

clean assembly.

• Improvement of operator positions versus critical RF surfaces (avoid

top assembly, request seated).

• Gate valve connection to pumping system procedure has been

reviewed recently to ensure better cleanliness (CC).


XFELX-Ray Free-Elect ron LaserSA-WS: pre-alignement of bellows

Observation during XM26 assembly



Cavity reception skipped:

avoids one leak check (LC),

including one angle valve

connection to pump unit,

and one open/close cycle

Clean Procedures: Cavity History

Abritrary units except for pressure level


Procedure n°1 : XM-3 to XM3

Courtesy S. Berry

Procedure n°2 : XM4 to XM53 (except XM27)

Cavity

Reception

Cold coupler assembly String assembly

Cavity history

Fin

al

LC


Fin

al

LC

Str

ing

LC

Str

ing

LC

Clean room assembly

Up

str

. fl

an

ge

Do

wn

st.

fla

ng

e

Clean room assembly C

ou

ple

r L

C

Co

up

ler

LC

LC

Ca

vit

y L

C

Cavit

y L

C

XFELX-Ray Free-Elect ron LaserClean Procedures: Cavity History


Procedure n°3 : XM27,

then XM54 +

Courtesy S. Berry

Procedure n°4 : XM75-79,

XM93-94

Cavit

y v

en

tin

g


Cavity history

String and coupler assembly

Clean room assembly

Up

str

. fl

an

ge

Do

wn

st.

fla

ng

e

Clean room assembly

Cavity string assembly is

followed by connection of

the 8 cold couplers w/o

pumping. This solution was

implemented during coupler

shortage periods: it saves

labor and and vacuum

operation.

Six days are needed to

assemble a full cavity string.

Co

up

ler

LC

Str

ing

LC

Fin

al

LC

F

ina

l L

C

Str

ing

LC

Cavit

y L

C

Cavit

y L

C

XFELX-Ray Free-Elect ron LaserClean Procedures: Comparison


Procedure n°1 n°2 n°3 n°4

# Gate valve to pipe connections 20 22 14 14

# Gate valve open/close cycles 29 21 13 13

# N2 blowing after an opening 17 17 9 9

# Leak checks 48 40 32 23

Number of vacuum operations for a complete cryomodule assembly

XFELX-Ray Free-Elect ron LaserCryomodule Performance: Procedure n°1


XM-3 : First pre-series module, 100 % made by CEA

(MT)

Module with large-grain cavities, will not go in the XFEL Tunnel

XFELX-Ray Free-Elect ron LaserCryomodule Performance: n°1-2 vs. n°3-4


Procedures n°3 and n°4

42 cryomodules

Eop = +0.4 MV/m

Procedures n°1 and n°2:

54 cryomodules

Eop = -2.0 MV/m

XFELX-Ray Free-Elect ron LaserCryogenic Heat Loads (XM1-XM95)


14 W at 2K

Specs for module static

+ dynamic heat loads

measured at 23,6 MV/m

16 W at 5/8K

125 W at 40/80K

Courtesy S. Putselyk,

S. Barbanotti

XFELX-Ray Free-Elect ron LaserPED Certification of He-Tank Ti Welds


• Implementing and complying to the PED certification, in particular the RT norms

‘NF EN ISO 17636-1 (2013) class B ’ for the execution and ‘NF EN ISO 10675-1

(2013) level 1’ for the interpretation, was a major effort over the year 2013,

spanning XM-1 to XM11 modules.

• The porosity problem in the Titanium orbital welds was

overcome by a combination of process cleanliness,

US cleaning of Ti-bellows and welder ‘humility’.

• Alsyom has successfully

taken over welding

coordination within the

‘EN ISO 3834-2’ norm.

Level 2 pores are repaired or subject to exemption.

No pore beyond 0.5 mm diameter, ‘level 1.5’.

Courtesy S. Barbanotti

XFELX-Ray Free-Elect ron LaserSummary of Module Repairs


XM24 involved the repair of a beam vacuum leak and of a coupler warm part

XFELX-Ray Free-Elect ron LaserSummary of Module Repairs

Non

conformity Repair Status

XM-2 Missing

PED – stamp

• Disassembled till 2-phase pipe accessible

• X-ray and TÜV check

• Retest OK

Module tested and installed in the

tunnel

XM8 Leak at 2 K

area

• Disassembled till 2-phase pipe is accessible

• Leak check and leak repair

• Retest OK but smaller leak at room T.

Module tested, leak reappeared

after warm-up.

Not accepted for tunnel

installation


Leak localized in the 8 mm / 10 mm transition from cavity vendor

(3 cases over the in total production)

XFELX-Ray Free-Elect ron LaserSummary of modules and repairs (2/2)

Non conformity Type of repair Comment

XM22

Leak at beam vacuum,

occurred after cool-down,

unstable cryogenics

conditions and warm-up

• Leaky HOM feedthrough ->

exchange under local clean room

• AMTF second test OK !!

Module tested

XM24


occurred after cool-down,

RF test and warm-up

• Leaky RF pick-up feedthrough ->


• AMTF second test OK !!

Module tested

XM46 Leak at beam vacuum

• Disassembled till string hanging in

cold mass

• Leak check -> tightening of the leaky

cold coupler connection on Cavity 4.

In use at CMTB: strong dark

current measured Cavity 6.


installation.

XM50 Leak at beam vacuum

• Disassembled till string hanging in

cold mass

• Leak check -> no leak found?

Module tested: strong FE and

leaky again !


installation

XM91


occurred during coupler

repair after cool-down,

RF test and warm-up

• Leaky HOM feedthrough ->


• Repair in progress

Module retested ??


XFELX-Ray Free-Elect ron LaserSummary of Test Results

Repair performed Tested

XM-2 at DESY Yes, OK

XM8 at DESY Yes, not usable in tunnel

XM22 at DESY Yes, OK

XM24 at DESY Yes, OK

XM46 at Saclay Yes, not usable in tunnel

XM50 at Saclay Yes, not usable in tunnel

XM54 at Saclay Yes, OK

XM91 at DESY, in progress Not yet


XFELX-Ray Free-Elect ron LaserXM50 repair

Problem: leak at the beam vacuum at 5x10-9 mbar.l/s before shipment

Repair:

• module disassembled till cavity string accessible

• Leak tests are negative: elusive leak on beam vacuum !

• A ‘leak’ of 10-10 mbar.l/s is detected on one of the angle valve

connected to a gate valve, already found in the clean room.


XFELX-Ray Free-Elect ron LaserRepair and Leak Check of XM50

• Decision on re-assembly.

• Lack of communication at Alsyom and of supervision by CEA: the

cold coupler bellow stiffeners are removed under beam vacuum

conditions and the module is transferred with fully compressed

cold bellows.

• Decision to continue and module is leak tight at shipment.

• The beam vacuum leak re-appeared at DESY → XM50 is discarded


Field emission

levels are very high

in most cavities

XFELX-Ray Free-Elect ron LaserXM22 repair

Problem: leak at the beam vacuum

Repair:

• module disassembled till cavity string accessible (at the cantilever)

• Leak test performed -> leak found at a HOM connector at Cav. 7 HOM

connector (CAV00613)

• HOM exchanged with local clean room -> new leak check -> no leak

Duration of the repair: 54 days

Results: cavity 7 with the new HOM does not show degradation



Module was disassembled for best access to

area of HOM Coupler at beam tube cavity

long side

A local cleanroom tent with horizontal

laminar air flow of ISO 4 Air quality is set up

XM22 - HOM Pick-up Exchange



Control and acceptance test

Air flow <= 0,35m /sec (anemometer)

Air quality n <= 10 Part. 0,3µm / sqft (Air

particle counter)

Surface particle contamination

n <= 10 Part. 0,3µm / sqft (Ionizer air

gun and Surface air flow based particle

counter)

Flow direction horizontal Clean room /

Fog generator

Local turbulences by accessories and

operator / fog generator

Surface area that could not be cleaned sufficiently, are covered

with anti static cleanroom foil




Work process is monitored by air particle counter

located below the HOM Coupler port

Exchange procedure is controlled and recorded by a

second operator outside of local cleanroom tend





Quench Limit

Operating Gradient

Cavity 7

Cavity 7


Preparation of XM54 cold mass on Roll-out Workstation

Downstream end connected for N2 flushing

and leak check

XM54 – Gate Valve Exchange


Leaky gate valve on its temporary support


Installation of local clean room hutch

The exchange procedure is controlled by a particle counter

in local cleanroom hutch and recorded



horizontal FFU laminar flow


Mechanical operations for gate valve exchange

Supporting the leaky gate valve on the sliding table



Connection of the new gate valve

under N2 flushing from both ends


Leak check of the connection,… and of the gate valve:



Coupler cold part holder

All coupler cold bellows were held stiff during

leak check and venting phase, except that of

coupler 1 !

As a consequence, coupler 1 cold bellow was

fully (axially) compressed during leak check.


Cavity 1 is strongly degraded by field emission.

Possible causes are a) exposure to gate valve,

b) cold coupler bellow full compression.



Operating Gradient

Cavity 1

MT @ 24 MV/m

VT @ 33-38 MV/m

XFELX-Ray Free-Elect ron LaserConclusions for Cryomodule Assembly

• E-XFEL Cryomodule Assembly at Saclay implied 4 main overlapping

phases:

1. Mastery of assembly procedures [ T1/2008 – T1/2013 ], with XM-3

2. Mastery of infrastructure and tooling [ T3/2010 – T1/2013 ], at XM-1

3. Mastery of non-conformities handling, both imported-PRODUCT and

PROCESS-generated non-conformities [ T3/2012 – T3/2014 ], at XM15

4. ‘Mastery’ of the industrial operator

• Productivity [ T1/2014 – T4/2014 ], at XM25

• Quality Assurance [ T4/2014 – ongoing ]

This process depends on the early availability of the cryomodule

components: ‘Practice makes perfect’

• The difficulties and the risks of coupler assembly had been under-

estimated by CEA, especially for the coupler warm part

• Better module RF performance is correlated to Clean Room practice and

Clean Room procedures.

• The goal of ‘zero mistake’ has been missed: the rate of ~ 1 major

mistake every 2 weeks is an organisational problem.


XFELX-Ray Free-Elect ron LaserConclusions (2/2)

• E-XFEL Cavity production demonstrates the existence of EU vendors

for cavities in the range 30 – 40 MV/m.

• E-XFEL AMTF demonstrates that RF testing is feasible) at a rate

compatible with one ILC hub, even if 100% MT is the chosen option:

11-day cycle per module, with 3 MT bunkers in AMTF

• E-XFEL Cryomodule Assembly demonstrates that a 3-day throughput

is feasible for ILC production, leading to about 120 modules per year

on one production site.

• When all assembly equipments are operating under nominal

conditions, there are clear indications that RF performance of the

cryomodules is impaired by:

• The invasiveness of operators in the clean room

• The invasiveness of vacuum operations on the beam vacuum. Both

can be mitigated with good quality control and floor inspections

• Clean room assembly can be further improved, qualitatively and

quantitatively, e.g. by unifying cold coupler and string assembly in a

unique workstation (2 shifts required to achieve 3-day throughput).



Thanks to my co-workpackage leaders:

WP03 K Jensch, WP09 S. Berry and A. Matheisen

Thanks to the CEA team:

C. Cloué, C. Madec, S. Régnaud, C. Simon

C. Boulch, P. Charon, J-P. Charrier, M. Fontaine, Y. Gasser, G. Monnereau,

J-L. Perrin, T. Trublet, B. Visentin

Thanks to ALSYOM

P. Pluvy, J. Dumas, C. Abdi, F. Déau, F. Chatillon,

M. Jurado and their team, G. Guillonneau (SEIV)

Thanks to DESY and LAL colleagues

S. Barbanotti, M. Schmöckel, H. Hintz, F. Hoffmann, W. Kaabi, D. Käfer,

R. Klos, L. Lilje, W. Maschmann, M. Schlösser, A. Verguet, and many others

Acknowlegments for Module Integration


the last of

the cavities



Thank you for your attention



Back-up slides

XFELX-Ray Free-Elect ron LaserAssembly Procedures


• The preparation, assembly and control work are described

in 145 procedures, ‘Fiches d’Instruction’, ‘used’ by the

operators.

• The first set of draft procedures was written by CEA, during

the Prototyping phase at DESY and Saclay, in English and

appended to the Call for Tender Specifications for Industrial

Operator selection

• Alsyom, the selected Industrial Operator, was in charge of

updating these procedures during the Pre-Series phase (3

modules) and to translate them in French for their usage

during the Series production phase.

• This process took much longer than expected.

e-xfel module completion and repair activities x-ray free … · 2016. 7. 5. · xfel cryomodule...

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