Crab cavities – cryogenic circuit and heat loads

Crab cavities – cryogenic circuit and heat loads

LHC crab cavity engineering meeting – Fermilab, USA

13-14 December 2012

K. Brodzinskion behalf of cryogenic team at CERN

K. Brodzinski - CC_Fermilab 20122

Contents• Cryogenics in SPS BA4 (regarding 2 K refrigeration)

• Capacity limitations with existing infrastructure• Cryogenic circuits• Available space – integration• Helium availability

• Cryostat design – analytical approach• Cryostat circuits• Instrumentation• Heat loads • Pressures, protection and safety, operation aspects• Helium volume and other practical aspects

• Budget• Planning time line (for SPS and P4 testing)• Concept of LHC P1 and P5 cryogenics• Conclusions


Cryogenic infrastructure in SPS BA4

CC x 2

black –> existing 4.5 K red –> to be constructed 2 K

Crab cavity cooling at 2 K TCF20 cryoplant used in pure liquefactionTCF20 means 20 l/h = 0.7 g/s of LHe

TCF2

0 T-

S D

iagr

am

Guaranteed capacity: 87.5 W @ 4.5 K(i.e. isentropic equivalent to ~0.85 g/s of liquefaction)

Capacity limitations of TCF20

120 W @ 4.5 K available in refrigeration mode ! (+ 35 %)

Giorgio Passardi


0.7 0.85 1.2Liquefaction capacity line [g/s]

Conclusions: Liquefaction capacity measurement mandatory to confirm cooling possibility @ 2 K


Sulzer-Linde TCF20 in BA4At SPS BA4 there is a 4.5 K cryogenic infrastructure used last time about 8 years ago for COLDEX experiment. It is foreseen to test its capacity and upgrade it for 2 K refrigeration – refurbishment is underway

Cold box TCF20

2 K pumping groups recovered from AMS

Renovated compressor + elec. motor – run test done

New power supply panel for compressor station

Revised, labeled and qualified pressure control system / oil removal system

TCF20 Cold box


Cryogenic circuits

CC x 2

Service module

Coupler intercept

End cone intercept

End cone intercept

Screen

Screen

R

LT

TT

PT

EHTT

EHTT

EHTT

EHTTJT

EHTT

black –> existing 4.5 K red –> to be constructed 2 K

Regarding 2 K refrigeration

CC cryostat

EH


Cryo integration in SPS

TCF20

SM

heater

Very tight integration if going behind the beam line (preferable because of distances to the client and free space in access gallery).


Helium availabilityBA4: one 8 m3 GHe tank – operation pressure is assumed at ~ 10 bara ~13 kg of helium

For operation is assumed that ~9 kg of helium would be liquefied 60 dm3 of LHe volume

TCF20 phase separator volume – estimated up to ~ 20 dm3

Conclusion:The CC x 2 cryostat should not be bigger than 40 dm3 (if reasonably possible)

Remark: The above approach is the first estimate taking into account the reliable operation. If more flexibility required for the cryostat, appropriate solutions may be applied (e.g. renovation of special inter-sites supply and recovery lines, second tank …).

Buffer line

Supply 200 bar from north zone

Recovery line to north zone

Connection with battery

8 m3 Compressor


Cryostat design – circuits 1/2Option 1: cold box is able to cover all heat load requirements.

9

CC x 2Coupler intercept

End cone intercept

End cone intercept

Screen

LT

TT

PT

EHTT

EHTT

EHTT

4.5 K IN J-T for 2 K IN 2 K OUT 50 K OUT

290 K OUT

Interfaces:- One flange for 4 cold process pipes- Three small tapping for helium gas recovery- One tapping for SV of 2 K helium tank (with helium guard)- One tapping for SV on the vacuum jacket- Instrumentation – as shown on the sketch above (PT, TT and LT on the helium bath)

EH



End cone intercept

End cone intercept

Screen

LT

TT

PT

EHTT

EHTT

EHTT

LN2 80 K IN J-T for 2 K IN 2 K OUT GN2 OUT

Option 2: cold box is NOT able to cover all heat load requirements (boost necessary – LN2 circuit added for intercepts, N2 solution is not recommended in the tunnel ).

Interfaces:- One flange for 2 cold process pipes- Two tapping for N2 circuit – inlet and outlet- Three small tapping for N2 gas recovery- One tapping for SV of 2 K helium tank (with helium guard)- One tapping for SV on the vacuum jacket- Instrumentation – as shown on the sketch above (PT, TT and LT on the helium bath)

Is it acceptable to have coupler and end cone intercepts at ~80 K?

Cryostat design – circuits 2/2

EH


InstrumentationInstrumentation proposal is presented below.

11


End cone intercept

End cone intercept

Screen

LT

TT

PT

EHTT

EHTT

EHTT

4.5 K IN J-T for 2 K IN 2 K OUT 50 K OUT

290 K OUTEH

Regulation – loop with LHe supply valve

Regulation – loop with GHe outlet valve

Indication – probably can be used for regulation if PT failsCold gas warming and regulation at 290 K

Cold gas warming and regulation at 290 K

For He evaporation/stabilization …

The type of instrumentation (technology), range, power (for EH) are not defined yet and will be discussed with related instrumentation and control engineers.

Protection and safety devices

Service module – circuits

12 K. Brodzinski - CC_Fermilab 2012

Screen (He or N2)

EHTTJT

The Service Module is to be designed and ordered/produced by CERN.

Subcooling heat exchanger and JT valve are to be integrated in dedicated service module.

LHe INGHe OUT

Cryostat


Heat loads 1/3

Will we have for SPS test a common cryostat for 2 cavities or 2 cavities in separated cryostats?

Common cryostat:+ lower total static heat load+ simple distribution system- direct influence of one cavity on the other (quenches)- difficult replacement of one cavity (regarding third cavity testing in SPS)

What will be approach for LHC final destination? SPS configuration should be as close as possible with decisions foreseen for LHC if possible.

Main open questions:


Heat loads 2/3Assumptions received/presented by two suppliers:

4R Crab cavityHeat Load in Watts

2K 5K 60K Static

1 Radiation 0.2 0.0 25.0 Computed estimates2 Support 0.1 1.2 57.2 Computed estimates3 Couplers 0.1 1.2 20.0 Educated guess4 Tuner 0.1 5.0 Educated guess5 Instrumentation 0.1 0.1 1.0 Educated guess6

Total Static 0.4 2.5 108.2 Dynamic

7 RF-Cavities 5.0 0.0 0.0Graeme Burt ~ 2.4W /cavity

8 RF-Couplers 0.2 2.0 40.0 Guestimate9 Beam (Radiation) 6.0 0.0 0.0 ???

10 Total Dynamic 11.2 2.0 40.011 Total Operating Load 11.6 4.5 148.212 With Safety Margin of 1.5 17.4 6.7 222.3

13 Available Capacity 24.0 25.0 150.0 Estimates Modified TCF-2014 Balance 6.6 18.3 -72.3

Incorrect values (capacity discussed on slide 3 and 4)

The values are for one module with 2 cavities (with request to comment on orange values).

Very rough estimation at max. 2 W for SPS

From Shrikant Pattalwar

? ?


Heat loads 3/3

From Jean Delayen – Frascati 2012


Heat loads and TCF20 capacityService module: 0.8 W@2 K, 2 [email protected] K, 80 W at 80 K (e.g. taken out with latent heat of LN2)

Module with 2 cavities (static + dynamic) without safety factors:7.2 W @ 2 K, 4.5 W @ 4.5 K ?, 148.2 W @ 60 K ?

Putting all together:8 W @ 2 K, 6.5 W @ 4.5 K ?, ~230 W @ 80 K

8 W @ 2 K(~0.4 g/s) 6.5 W @ 4.5 K

(~0.33 g/s)

Could be a difficult limit

0.7 0.85 1.2Liquefaction capacity line [g/s]

Transfer and screen …?Exercise for screen:Assumptions: available GHe@5K, heat load of 230 W on screen, outlet GHe temp at 80K -> 0.6 g/s of flow is neededIt means that: 100 liter dewar would be empty in ~6 hours.

Preliminary conclusions (for thermal aspects we know today): • one cryostat for 2 cavities in the best case or only one cavity test to be done• using of LN2 seems to be an obligation


Pressures – safety :

• The cavity should be designed to withstand external pressure of 2.6 bara (deltaP = 2.6 bar) at ambient temperature without plastic deformation,

• Design pressure for the cryostat should be based on installed safety devices according to design rules (cryostat equipped with a rupture disc set at 2.2 bara and safety valve set at 1.8 bara)

• both safety devices should be placed on the cryostat in the way to avoid potential projection of helium towards the passages or transport area (deflectors installation to be analyzed),

• Both safety devices should protect cavity and cryostat from pressure rise causing plastic deformations

• Operating pressure during the cool down can oscillate between 1.2 and 1.5 bara – estimation,

• Normal operation pressure will be set at ~ 20 mbara (for 2 K cooling)

Cryostat operation – first approach

Cool down – stable operation – warm up:

• Cool down will be done with direct filling of LHe to the cavity cryostat, very roughly estimated cool down time is ~ 1 day

• Stable operation availability will be affected by impurities in the system (there is no purifier installed in the infrastructure). A few days continues availability should be guaranteed.

• Warm up of the cavities will be done by natural evaporation of helium and temperature floating towards 300 K (additional heater on the helium bath can be used to speed up the process)


Helium volumeEstimation of needed helium volume in the cryostat – for one cavity.

18

Volume A – layer of L mm of helium,Volume B – additional helium volumeVolume C – additional head of helium for transients(for C=7dm3 -> ~30 min for head evaporation, loading at 20 W)

Assumptions:• Cavity in shape of a cylinder (D=175 mm, Lcav=700 mm)• Helium layer of L mm of thickness analyzed (see data below)• Head of additional Lc=50 mm layer of He taken above the cavity (see figure below)

Volume A

Volume B

Volume C

L A B Lc C total He volumemm dm3 dm3 mm dm3 dm310 4.66 2.94 50 7.02 14.6220 10.02 3.68 50 7.96 21.6630 16.12 4.51 50 8.93 29.5640 22.99 5.45 50 9.95 38.3950 30.66 6.5 50 11 48.16

Operation with one buffer tank of 8 m3 is limited …

“The CC x 2 cryostat should not be bigger than 40 dm3 (if reasonably possible)”

L

LcLcav

D

L


GHe return collectorRecommendations coming from LHC cryogenics operation.

19

~ 30

mm

~100

mm

LHC RF GHe return line (too low for reliable level regulation)

GHe return collector should be placed on side as presented in above sketch, with reasonable distance above LHe level (~ 100 mm) for reliable level regulation (avoiding LHe presence in return line). The supply tapping is recommended to be placed in gas volume “far” from outlet pumping ports for efficient separation during the filling.

Volume of ~10 – 15 liters is to be respected (without collector)


Crab-cavity test in SPSAdditional specific 2 K equipment

• Refurbishment of existing equipment (4.5 K) 150 kCHF • Sub cooling heat exchanger 12 kCHF• Warm pumping unit (WPU) 100 kCHF• He guard for pressure relief valves 10 kCHF• VLP heater 20 kCHF• JT expansion valve 4 kCHF• Service Module + piping 50 kCHF

• Total ~350 kCHF

Remarks: 1. some additional cost for cryostat design can occurred e.g. beam screen circuit on second beam pipe2. if WPU cannot be installed underground, a new VLP line must beintegrated in the BA4 shaft (DN100 – 20 kCHF)3. No specific purifier foreseen for impurity management of the VLP circuit, i.e. availability affected in case of 2 K refrigeration.

Tentative SPS CC cryogenic schedule


• Surface equipment (GHe storage, compressor station and oil separation system)

– refurbishment completed (run test done on 28.11.2012) – first results OK

• Cold box refurbishment is underway – run test on the beginning of LS1

• Installation of liquefaction test instrumentation and test performance –

by 15 June 2013 (cut of cooling water in SPS BA4 until ~ 15 September 2013).

• Development, installation and commissioning of 2 K equipment by end of LS1

Remark:Integration of 2 K cryo equipment in the tunnel looks tight – if not possible heavy complications – possibility of mentioned transfer line construction in the shaft to the surface = more logistics, more manpower and time required.


Crab cavity test at Point 4• The global scheme is no longer an option for the final HL-LHC, but a prototype cavity could be

installed in Point 4 after the tests in SPS.

• Installation of CC prototype could be:– Coupled to the RF cryogenic upgrade at P4 with 2 K equipment to be added– Scheduled during the LS2 (2018) for possible validation tests during 2019/20/21 (before the LS3 for P1/5

upgrade).

Is this test essential and really necessary to be performed ?

• If yes and if before availability of new cold box hard difficulties appears:• Existing cryo distribution to be modified and test performed at 4.5 K• Existing cryo distribution to be modified and 2 K pumping system to be added• TCF20 from SPS to be relocated …


Cooling of CC modules at P1 and 5• Two possibilities:

– Via the 2 new cryoplants dedicated to the new inner triplets at IP1 and IP5 or– Via the 4 existing adjacent-sector cryoplants

• The choice will depend strongly on:– the operating temperature of the new Inner Triplets (IT): 4.5 K vs 2 K– the total added heat loads

Remarks:• It is probably preferable to link the CC with new refrigerators for ITs, if not we will recreate

currently existing in s3-4 and 4-5 unbalance which has justified upgrade of cryo at P4 • Studied schemes of cryogenic upgrade for HL-LHC at P1 and 5 were presented in Frascati on

Friday 16.11.2012 at 10h00 “Cryogenics for HL-LHC” by Laurent Tavianhttps://indico.cern.ch/conferenceTimeTable.py?confId=183635#all.detailed

Existing Cryo plants

New Cryo plant for RFs New Cryo plant for ITs and … CC

Sector 3-4 Sector 4-5 Sector 5-6LHC RFs

P5

CCB

WCS

UCB

Storage

CCB

WCS

UCB

Storage

D2CCQ4Q5Q7 IT IT D2 CC Q4 Q5 Q7D1Q6 D1 Q6

A AX

Cryo-magnet @ 1.9 K pressurized

Crab-cavity @ 1.9 K saturated

Cryo-magnet @ 4.5 K saturated

Current feed box

Cryo-infrastructure

Superconducting links

Cryogenic distribution line

Warm recovery line

Warm piping

P1 & P5 layout 1: Matching section cooled with sector cryoplants

P1 or P5S81 or S45 S12 or S56

Frascati 2012 by L. TavianK. Brodzinski - CC_Fermilab 2012 24

CCB

UCB

Storage

D2CCQ4Q5Q7 IT IT D2 CC Q4 Q5 Q7

CCB

WCS

UCB

Storage

D1Q6 D1 Q6

A AX

Cryo-magnet @ 1.9 K pressurized

Crab-cavity @ 1.9 K saturated

Cryo-magnet @ 4.5 K saturated

Current feed box

Cryo-infrastructure

Superconducting links

Cryogenic distribution line

Warm recovery line

Warm piping

P1 & P5 layout 2: Matching section cooled with inner triplet cryoplants

P1 or P5S81 or S45 S12 or S56

Frascati 2012 by L. TavianK. Brodzinski - CC_Fermilab 2012 25


Conclusions• Prototype crab-cavity testing in SPS:

– Test possible from end 2014.– Refrigeration at 2 K:

• liquefaction capacity of the TCF20 must be measured and sufficient.• Additional resources (P + M) must be allocated.

– Additional 2 K infrastructure to be built – could be in conflict with the LS1 activities – tight to be integrated.

• Prototype crab-cavity testing at LHC P4:– If test necessary before availability of a new cold box -> difficulties for infrastructure– 2 K cooling (~1 MCHF + 2 FTE + a possible noise-insulated building tension/construction…?).

• Series crab-cavities for the final HL-LHC local scheme:– Cryogenic implementation during the LHC LS3 (2022)– 2 K cooling via new ITs cryoplants preferable:

• Option for Matching Section area to be cooled by the same new cryoplant• Cooling with existing sectors cryo plants not excluded but with load unbalance wrto the other LHC sectors


THANK YOU FOR YOUR ATTENTION !

• Is it acceptable to have coupler and end cone intercepts at ~80 K?• Heat loads clarification at 5 K and 60 K (for 4R cavity)• SPS test – common or separated cryostat?• Is the P4 test really necessary? (if yes -> When? At what temperature?)• …

Remind of main open points:

Discussion

Crab cavities – cryogenic circuit and heat loads

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