cern cryomodule requirements for crab c avities

The HiLumi LHC Design Study is included in the High Luminosity LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.

CERN Cryomodule Requirements for Crab Cavities

O. Capatina (CERN)

LHC Crab Cryomodule meetingOC, 2/August/2013 1

Functional specification

OC, 2/August/2013 LHC Crab Cryomodule meeting 2

https://espace.cern.ch/HiLumi/WP4/Lists/Team%20Discussion/AllItems.aspx

• SPS tests

• LHC final configuration

General


• LHC environment

General


• LHC environment

~ 10m

General


D2 Q4Q4 D2IP

• LHC environment

General


• SPS environment

General


• SPS :• 2 (identical) cavities in a cryomodule• 3 different cryomodules

General



General


• SPS :

Geometrical constraints


• SPS :



• SPS dummy beam pipe :



LHC configurationSPS configuration

• SPS - dummy beam pipe :• Dummy LHC beam pipe at 194mm horizontally

from the SPS beam pipe• Dummy beam pipe can be on either side of the

cavity but preference opposite to Y chamber



• SPS – Y chamber apperture:• With new Y chamber (510 mm aperture),

SPS cryomodule transverse dimensions coherent to LHC => could allow similar SPS/LHC basic solutions for tuner, coupler position

• SPS cryomodule design should not be over-constrained

• Baseline: replacing the existing SPS Y chamber



• SPS interfaces:• Connexions to main coupler

• From top, vertically



• SPS interfaces:• Connexions to main

coupler • Limit risk of loads

transmitted directly to the cavity from connection to RF module – Double walled tube could be used as part of the supporting system of the cavity



• SPS interfaces:• Connection to cryo

• From top, vertically for main circuits• N2 warm return may be sidewise



helium tank

crab cavity

common pumping collector

thermal screen at ~80 Kcryostat interface

CWT

Power coupler intercept

CWT

• LHC - Alignment requirements (position accuracy and position stability) – based on general beam dynamics considerations:• Transverse rotation per cavity should be less than 5 mrad• Transverse misalignment per cavity (in both planes) should

be less than 0.7 mm• Cavity tilt with respect to the longitudinal axis should be

less than 1 mrad• Cavity longitudinal misalignment should be less than 10

mm

• Active alignment will be studied in a dedicated set-up

Alignment


• SPS • Alignment required for operation less than LHC

• To limit SPS crymodule complexity (win time and limit risk)• No active alignment needed for SPS tests • Foresee a system for monitoring the cavity

positions instead

Alignment


• Operated at 2 K saturated helium bath -> ~30 mbar• Two circuits: 2 K and 80 K• Main interface from the top with 4 main lines

(LHe IN, GHe pumping, 80 K IN and 80 K OUT):• internal pipes welded, external envelope bolted

Process & instrumentation


helium tank

crab cavity



CWT


CWT

See Krzysztof’s talk

• 80 K screening will be provided with He or LN2• Power couplers and Cold/Warm Transitions

intercepts at 80 K, then outgoing gas directed to recovery line



helium tank

crab cavity



CWT


CWT

• In general: maximize instrumentation for the prototypes• Minimum instrumentation requirements:

• Gauge for helium level measurement from the bottom through the phase separator to be installed for each helium tank (LT x 2)

• Pressure measurement on the saturated helium bath (PT x 1)• Temperature measurement on the bottom each helium tank

(suggested CERNOX type transducer, TT x 2)• Electrical heaters of 50 W on each helium tank (EH x 2)



helium tank

crab cavity

common pumping collectorthermal screen at ~80 K

cryostat interface

CWT


CWT

SKETCH

LT PT

EH

TT

EH

TT

LT

• Temperature measurement on 80 K screen line (TT x 2 on inlet and outlet)

• Instrumentation for 80 K intercept circuits – definition underway• JT valve and sub-cooling HX are foreseen to be installed out of

the cryostat • All sub atmospheric instrumentation/safety devices with ambient

air interface will have to be equipped with appropriated helium guard.



helium tank

crab cavity



CWT


CWT

SKETC

HLT PT

EH

TT

EH

TT

LT

• Pumping collector sizing (recommended 100mm dia)• Gas speed lower than 5 m/s• Min 50 mm for level regulation, additional buffer

for ~ 20 min of operation• Compatibility with safety devices for pressure limit

requirements to be confirmed

Piping sizing


0 20 40 60 80 100 1200.001.002.003.004.005.006.007.008.00

Pumping collector gas speed *

Level of liquid in the double phase line [mm]

He g

as sp

eed

[m/s

]

92

* Calculation done assuming: collector diameter of 100 mm, He mass flow = 2 g/s, GHe temp = 2 K, GHe press = 20 mbar.

100 mm~90 mm

0 mm

Liquid level

~50 mmRegulation

maxi: 5 m/s

• Helium tank to be dimensioned correctly to extract maximum heat load • Heat flux in He II depend on bath temp. and

channel dimension

Helium tank sizing


• Helium tank to be dimensioned correctly to extract maximum heat load • If helium cross section expected to

extract (order of magnitude) 1 W/cm2 => detailed calculations needed

• Minimize reasonably the liquid helium volume (max. 40 L/cavity if possible)

Helium tank sizing


Heat load budget


HL per cryomodule HL @2 K [W] HL @ 80 K

(TS) Comment

Dynamic

Deflecting mode 5.0 - Confirmed? Other Order

Modes TBD TBD

RF Coupler TBD TBD Beam Current 0.5 Tentative

Static

Radiation (cavity +Phase Sep. Cold surface + Thermal

Shield

0.2 6.8

Rescaling from LHC o W/ m2 @ cold mass

o 1.7 W/ m2 @ Thermal shield

CWT

0.557(rad) + 0.892(cond) =

1.5W x 2 = 3.0

0.625(rad) + 5.926 (cond) =

6.6W x 2 = 12.6

1 heat intercept @ 80K in the middle

Supporting System 1.0 3.3 6 tie rods/cavity

RF Coupler

0.501(rad) + 0.853(cond) =

1.4W x 2 = 2.7

0.587(rad) + 5.662 (cond) =

6.3W x2 = 12.6

1heat intercept @ 80K in the middle

Cables & Instrumentation 1.0 - Tentative

Other order modes TBD TBD Design dependent

Totals ~13.4 + TBD ~34.9 +TBD

• Given its designated function, we are in the presence of ‘high safety relevance’ equipment, i.e., special equipment according to CERN’s SR-M;

• The HSE Unit Safety Commission shall give clearance from design’s release to commissioning;

• A Safety File with all relevant technical documentation to be approved by the Safety Commission shall be prepared from day 1 (EDMS);

Safety equipment

OC, 2/August/2013 LHC Crab Cryomodule meeting 33See talk of Luis

• Two design strategies are possible: to EN Standards or to ASME Section VIII + specific technical requirements;

• Combined design (EN+ASME) can be accepted if justified;

• Design shall target the hydrostatic test pressure of 2.6 bar (abs, helium vessel);

• Equivalent to EN conventional material grades are preferred;

• ‘Non-conventional’ material properties are to be demonstrated by testing.

Safety equipment


• Helium tank material not imposed; however titanium involves

• More complex interfaces • Not covered by the Harmonised

European Standards

• Stainless steel flanges (1.4429, AISI 316LN) for beam pipe interface

• Equivalent to EN conventional material grades are preferred

Materials


• Static magnetic field shielding required• The field to be below 1 µT at the outer

surface of the cavity • Numerical simulations to determine the

material thickness and specification, as well as geometry

Magnetic shielding


• Integration into cryostat at CERN - most likely location SM18

Cryostating


• SPS cryomodule:• Expected 3 different conceptual designs

by the end of the year

• Collaboration with regular working sessions to merge CERN requirements and LARP/UK effort

• CERN is ready to help with several competencies

Concluding remark


cern cryomodule requirements for crab c avities

Documents

sps dummy beam pipe

sps dummy beam pipe

crab cavitieso

sps beam pipedummy beam

sps environment generaloc

dummy lhc beam pipe

cern cryomodule requirements

sps y chamber apperture