Status of the SPL cryo-module development

V.Parma, TE-MSC(with contributions from WG3 members)

SPL seminar, CERN 18th February 2010

Content

• SPL architecture and parameters• Work organisation• Layout studies and machine sectorisation

(vacuum+cryogenics)• Cryogenic scheme (for the prototype)• Supporting schemes• Next steps• Summary

SPS

PS2

SPL

Linac4

PS

ISOLDE

Layout injector complex

The SPL studyGoals of the study (2008-2012):• Prepare a Conceptual Design Report with costing to present

to CERN’s management for approval• This is the low power SPL (LP-SPL) optimized for PS2 and

LHC

Length: ~430 m

Medium b cryomodule

High b cryomodules

Ejec

tion

10 x 6b=0.65 cavities

5 x 8b=1 cavities

13 x 8b=1 cavities

TT6

toIS

OLD

E

Debunchers

To P

S2High b cryomodules

From

Lina

c4

0 m0.16 GeV

110 m0.73 GeV

186 m1.4 GeV

427 m4 GeV

Kinetic energy (GeV) 4Beam power at 4 GeV (MW) 0.16Rep. period (s) 0.6Protons/pulse (x 1014) 1.5Average pulse current (mA) 20Pulse duration (ms) 1.2

LP-SPL beam characteristics

The SPL study (cont.d)• Study a 5 GeV and multi MW high power beam, the

HP-SPL• Major interest for non-LHC physics:

ISOLDEII/EURISOL/Fixed Target/Neutrino Factory

Length: ~500 m

Ejec

tion

to

Euris

ol

High b cryomodules

12 x 8b=1 cavities

Medium b cryomodule

High b cryomodules

Ejec

tion

10 x 6b=0.65 cavities

5 x 8b=1 cavities

6 x 8b=1 cavities

TT6

toIS

OLD

E

Debunchers

To P

S2High b cryomodules

From

Lina

c4

0 m0.16 GeV

110 m0.73 GeV

186 m1.4 GeV

~300 m2.5 GeV

Option 1 Option 2

Energy (GeV) 2.5 or 5 2.5 and 5

Beam power (MW) 3 MW (2.5 GeV)or

6 MW (5 GeV)

4 MW (2.5 GeV)and

4 MW (5 GeV)

Rep. frequency (Hz) 50 50

Protons/pulse (x 1014) 1.5 2 (2.5 GeV) + 1 (5 GeV)

Av. Pulse current (mA) 20 40

Pulse duration (ms) 1.2 0.8 (2.5 GeV) + 0.4 (5 GeV)

HP-SPL beam characteristics

~500 m5 GeV

Cryo-module: Goal & MotivationGoal:• Design and construct a full-scale cryo-module prototype

(part of the SPL Design Study)

Motivation:• Develop technologies and demonstrate construction

capability on a cryo-module with 8 β=1 cavities

• Learning of the critical assembly phases (e.g. clean-room)

• Enable RF testing on a multi-cavity assembly in real operating conditions (horizontal cryostat)

• Investigate and acquire experience on cryogenic operation issues (e.g. process control)

Working group (WG3) members System/Activity Responsible/member Lab

Machine architecture F.Gerigk CERN, BE/RF

WG3 coordination V.Parma CERN, TE-MSC

Cryo-module conceptual design & Integration

V.Parma, N.Bourcey, A.Vande Craen, D.Caparros, P.Coelho, Th.Renaglia

CERN, TE/MSC, EN-MME

Cryostat detailed design P.Duthil CNRS/IN2P3-Orsay

Cryostat assembly tooling S.Chel CEA-Saclay

WG 2 activity (RF cavities/He vessel/tuner, RF coupler)

W.Weingarten/S.Chel/O.Capatina/E.Montesinos

CERN BE/RF, CEA-Saclay

Vacuum systems S.Calatroni CERN, TE/VSC

Cryogenics U.Wagner CERN, TE/CRG

Survey D.Missiaen CERN, BE/ABP

Quad.doublet D.Tommasini CERN, TE/MSC

• Regular WG meetings since May 2009– Web page: https://twiki.cern.ch/twiki/bin/view/SPL/CryoModules

• Topics covered (or in progress): – Cryomodule longitudinal study– SPL mechanical layouts– Sectorisation issues– Cryogenic cooling schemes– Integration of RF Coupler– Cryo-module design: supporting systems, thermal shielding,...

• Close collaboration with WG2 (cavities and ancillaries)• Relevant workshops 2009:

– Workshop on Mechanical issues of SPL cavities/cryomodules: http://indico.cern.ch/conferenceDisplay.py?confId=68968

– Workshop on Cryogenic and vacuum sectorisation of the SPL: http://indico.cern.ch/conferenceDisplay.py?confId=68499

• Coming up soon (16-17 March): Review of the RF Couplers

Activity of WG 3

Planned supplies for prototype cryo-moduleInstitute Responsible

personDescription of contribution

CEA – Saclay (F) S. Chel 1. Design & construction of 2 β=1 cavities (EuCARD task 10.2.2)2. Design & construction of 2 helium vessels for β=1 cavities

(French in-kind contribution)3. Design & construction of cryostat assembly tools (French in-

kind contribution)4. Supply of 8 tuners (French in-kind contribution)

CNRS - IPN – Orsay (F) P. Duthil 1. Design and construction of prototype cryomodule cryostat (French in-kind contribution)

Stony Brook/BNL/AES team

I.Ben-zvi (Under DOE grant)1. Designing, building and testing of 1 β=1 SPL cavity.

CERN O.Capatina 1. 8 β=1 cavities2. 7 He tanks in titanium3. 1 He tank in st.steel

CERN E.Montesinos 1. 10 RF couplers (testing in CEA, French in-kind contribution)

Cryo-modulelongitudinal integration study (β=1)

+

Continuous cryostat "Compact" version (gain on interconnections):

5 Gev version (HP): SPL length = 485 m (550 m max available space)

"Warm quadrupole" version (with separate cryoline):

5 Gev version (HP): SPL length = 535 m (550 m max available space)

Longitudinal mechanical layouts«Continuous» vs. «fully segmented» cryostat SPL layouts

CRYOGENICS AND VACUUM SECTORISATIONOutcome of workshop on cryogenic and vacuum sectorisations of the SPL

(November 9-10, 2009)

Possible cryogenic feeding:“continuous” cryostat

Cryogenic Interconnect BoxCryo UnitCryogenic bridge

Cryo-plant

Isolde extractionEurisol extraction

CIB

CIB

10 β=0.65 + 5 β=1 cryo-modules17 β=1 cryo-modules + 2 demodulators

6 β=1 cryo-modules

1.7% tunnel slope

“continuous” cryostat

String of cryo-modules between TSM

Technical Service Module (TSM)

Cold-Warm Transition (CWT)

• “Long” and “continuous” string of cavities in common cryostat• Cold beam tube• “straight” cryogenic lines in main cryostat• common insulation vacuum (between vacuum barriers, if any

present)

Insulation vacuum barrier

Warm beam vacuum gate valve

Possible cryogenic feeding:Cryogenic Distribution Line

Cryogenic Interconnect BoxCryo-module UnitsCryogenic Distribution Line

Cryo-plant

Isolde extractionEurisol extraction

CIB

CIB

10 β=0.65 + 5 β=1 cryo-modules17 β=1 cryo-modules + 2 demodulators

6 β=1 cryo-modules

1.7% tunnel slope

“segmented” cryostat

String of (or single) cryo-modules

Technical Service Module (TSM)

Cold-Warm Transition (CWT)

• Cryostat is “segmented”: strings of (or single) cryo-modules, 2 CWT each• Warm beam zones• Cryogenic Distributio Line (CDL) needed• Individual insulation vacuum on every string of cryo-module (Vacuum

Barriers, w.r.t. CDL)

Cryogenic Distribution Line (CDL)

Insulation vacuum barrier

Warm beam vacuum gate valve

Main issues• Machine availability:

– “work-horse” in the injection chain

• Reliability of built-in components and operational risks– Typical faults expected on: cavities, couplers, tuners...– Operation with degraded performance (cavities, optics, leaks...)

• Maintainability:– Warm-up/cool-down . Time and reliability. Need for partial or complete warm-up of

strings to replace built-in components or even one cryo-module– Accessability of components for regular maintenance or repair

• Design complexity of compared solutions

• Operational complexity (e.g.cryogenics with 1.7% slope)

• Installation and commissioning

• Safety. Coping with incidents (MCI): Loss of beam and/or insulation vacuum (helium and air leaks):

• Cost differences between options

VACUUM

SPL Sectorisation Variants

09/11/09Vacuum sectorisation 22

Continuous

SegmentedOption B

SegmentedOption A

P.Cruikshank

Summary: comparison of vacuum aspects“continuous” cryostat Segmented with CDL

Advantages Drawbacks Advantages Drawbacks

Design

-Compact long.layout-fewer components-Reduced vac systems (integrated He lines)

- Long beam vacuum sectors , cold sector valves don’t exist!- Some sensitive equipment needs vacuum compatibility and validation

-Modular design- Easier access, repairs, upgrades- Modules are complete & tested before installation

-More vacuum components (eg CWT)-More vacuum instrumentation

Installation

-Insulation vacuum systems are exposed to tunnel environment- Beam/cavity vacuum more exposed?

-Minimize tunnel work/problems modules are complete and tested before installation- Staged acceptance tests- Decoupling of problems

Repair

- Less tasks for systematic repairs on modules – venting, re-pumping..

- Equipment will see more thermal cycles –> create leaks?

- Reduced search/repair zones- Reduced coactivity- Local warm-up and opening of vacuum system – cost & downtime

- Difficult access at CWT – not std interconnect design

Commisioning

- Cavities re-commissioning after venting -RF processing with helium required for field above < 6 MV/m- Movable blocks or valves to absorb field emission electrons?

-Pre-commissioning before installation- Staged tests – smoothing of resources, - Earlier identification of problems- Decoupling of problems - Re-commissioning of ‘weak’ module possible

- More volumes to commission

Operation

Simpler controlsRedundancy in fixed pumping systems

MCI would affect more equipment - Limit MCI affected zone by interlocked beam vacuum valves- Limit zone of degraded ins vacuum (helium leak)- Easier diagnosis of problems

- More equipment (fixed pumping systems & valves)- More interlocks- More risk of equipment failure- More maintenance

CRYOGENICS

2.2 K forward

5 K forward

40 K forward

2 K 2-phase

cavity

2 K return

80 K return

8 K return

cool down/warmup

support

coupler

300 mm

• Cavities cooled with helium II at ~ 2.0 K (3.1 kPa), similar to XFEL– Cavities inside saturated bath (slightly sub-cooled due to hydrostatic head)– Profit from low Δp and good p-stability

Cryogenics

JTVapourLiquid

Gas returntube

Two phasetubeBeam tube

Vapor flow large

XFEL

Effect of slope

Module Schemes

6/11/2009SPL Workshop NOv. 2009 26

Scheme no 3: “ILC-like”

LP SPL HP SPL

Diameter “x” [mm]

40 80

1.7 %

U.Wagner

Module Schemes

6/11/2009SPL Workshop NOv. 2009 27

Scheme no 7 : “ILC like SPL version “A” with separate cryogenic line equipped for independent cool-down,

warm-up and purge”

1.7 %

U.Wagner

Separate cryogenic line

· Advantages· Less complexity for the main cryostat· Potential to completely isolate “faulty” modules

· Disadvantages· Requires more tunnel space· Higher static heat load

· Cost aspect· Not easy to identify separate line most probably

more expensive· More complex cryostat and installation vs. cryostat

plus line, two installations and more tunnel space

6/11/2009SPL Workshop NOv. 2009 28

Advantages / Disadvantages

U.Wagner

modified cryogenic scheme (proposal)

Warm recovery lineWarm valves

Cryogenic issues (ongoing)• High dynamic heat load: ~200 W/cryo-module (~25 W/m)!

– Thermal break-down to be checked (q<qfilm boiling?)– Keep (efficient) stratified flow in bi-phase pipe R&D & testing

• High dynamic heat loads requires large design capacity (=diameter) of helium Gas Return Pipe (GRP):– Limit number of cryomodules in series– Large GRP: better in a cryo distribution line

• Pipe sizing: – Bi-phase pipe:

– HL dependant (vapour mass flow). 200W ~ 14 g/s per module , for v=1m/s Φ 140

– GRP: – HL dependant (vapour mass flow). 200W – can be kept relatively small with a CDL

– Coupler gas cooling– Thermal shield pipes

• Desy (XFEL/FLASH): continuous cryostat– Maximise real estate gradient– Minimise capital cost– Safety issues (MCI, catastrophic venting)

• Recent full-scale tests (after LHC sect. 3-4 incident)• Considering installation of cold valves (R&D ongoing)

• FNAL (Project X)– Now addressing segmentation issues– IC-2 (CW) will be more finely segmented than IC-1 (pulsed)

• JLAB (CEBAF):– Next slide

Experience from other labs

CEBAFTotal of 57 independent Cryostats

• Planned as full segmented• Staged construction/upgrade• Remove and replace

cryomodules: ~ 1wk !• Refurbish cryomodules:

– 1 to 2 per year over next 3 years

Failure experienceReliability of built-in components

Component Type of faults Degraded performance

Mitigating measures Source

1

Cavity(ies) - Low gradient - Lower acceler. - Compensate with higher grad. on other cavities or built-in margin

- JLAB, SNS

2 Coupler - Leak to cavity vac.

3

Tuner - Motor failure - Cavity not tuneable

- Compensate with higher grad. on other cavities or built-in margin

- Flash, 1 case- KEK moved motor

outside the cryostat

4Quadrupole/steerers

- Misalignment- No powering

- beam quality- Unacceptable

- New correcting scheme

- None

5

He envelope He Leak to ins.vacuum

Degraded ins.vacuum (10-4mbar) high heat loads

Additional pumping capacity and cryogenic capacity

- Flash, 2 major leaks, He vessel and bellows.

- JLAB, Cebaf

6Ins.Vac. envelopes

Catastrophic air leak to cavity vacuum

XFEL experiments

• Drivers:– Availability:

• Reliability/Maintainability. Components with technical risk:– RF Coupler, single window. No in-situ repair possible– Cavity/tuner, reduced performance. No in-situ repair possible– Beam/cavity vacuum leaks. No in-situ repair possible

possibility for quick replacement of cryo-module (spare)

– Safety: coping with incidents: accidental loss of beam/cavity vacuum:• Cold valves not available (XFEL is considering their development)

Adopt warm interlocked valves (not necessarily very fast, XFEL experience)

“Segmented” layout with CDL has clear advantages in these respects

• Additional advantages:– Magnets can be warm: classical “off-the shelf”, easy alignment/maintainability/upgrade – and cryo-module internal positioning requirements can ne relaxed (by 3)

• Drawbacks:– Less compact layout (~10%) – More equipment (CDL, CWT, instrumentation...):

• Capital cost• More complexity = less reliability?

– Higher static heat loads (but dynamic loads dominate!)

Conclusions on sectorisation

β=0.65 cryo-module

β=1 cryo-module

Fixed support

Sliding support

Inertia beam

Invar longitudinal positioner

External supports (jacks)

RF coupler

Possible supporting schemes

Fixed support

Sliding support

Inertia beam

Invar longitudinal positioner

External supports (jacks)

RF coupler

Possible supporting schemes

Fixed support

Sliding support

Inertia beam

External supports (jacks)

RF coupler + longitudinal positioner

Possible supporting schemes

External supports (jacks)

RF coupler + longitudinal positioner + vertical support

Intercavity support structure

Possible supporting schemes

RF coupler as cavity support

• Issues:– Mechanics– Cavity RF gasket – Stability w.r.t. T profile changes

(gas cooling control?)– Assembly sequence/tools...

Next steps– Refine design parameters for HP SPL (HL in particular)– Refining test objectives of the prototype

• Test program: RF, cryogenics• Infrastructure needs: RF power, cryogenic test station and

feedbox – Finalise choice of cryogenic scheme– Finalise operational scenarios, pressures and

temperatures – Piping sizes – Continue investigation of supporting systems (RF

coupler) Finalise conceptual design by mid 2010

Schedule for prototype

Summary• Cryo-module prototyping is mandatory to demonstrate

technology and provide a machine-representative test bed for RF and cryogenic testing

• An important involvement (with H/W contributions) from external labs is now firmly engaged

• The conceptual design is well progressed but still needs some months of work

• RF coupler design will be reviewed in March• Detailed cryostat design should start in the 2nd half of

the year• Assembly of the prototype cryo-module by end 2012