1. CERN Cryomodule Requirements for Crab Cavities
O. Capatina (CERN)
OC, 2/August/2013
LHC Crab Cryomodule meeting

2. Functional specification
OC, 2/August/2013
LHC Crab Cryomodule meeting

3. LHC Crab Cryomodule meeting
General
SPS tests
LHC final configuration
OC, 2/August/2013
LHC Crab Cryomodule meeting

4. LHC Crab Cryomodule meeting
General
LHC environment
OC, 2/August/2013
LHC Crab Cryomodule meeting

5. LHC Crab Cryomodule meeting
General
LHC environment
~ 10m D2 Q4 IP
OC, 2/August/2013
LHC Crab Cryomodule meeting

6. LHC Crab Cryomodule meeting
General
LHC environment
OC, 2/August/2013
LHC Crab Cryomodule meeting

7. LHC Crab Cryomodule meeting
General
SPS environment
OC, 2/August/2013
LHC Crab Cryomodule meeting

8. LHC Crab Cryomodule meeting
General
SPS environment
OC, 2/August/2013
LHC Crab Cryomodule meeting

9. LHC Crab Cryomodule meeting
General
SPS :
2 (identical) cavities in a cryomodule
3 different cryomodules
OC, 2/August/2013
LHC Crab Cryomodule meeting

10. LHC Crab Cryomodule meeting
General
SPS :
2 (identical) cavities in a cryomodule
3 different cryomodules
OC, 2/August/2013
LHC Crab Cryomodule meeting

11. LHC Crab Cryomodule meeting
General
SPS :
2 (identical) cavities in a cryomodule
3 different cryomodules
OC, 2/August/2013
LHC Crab Cryomodule meeting

12. Geometrical constraints
SPS :
OC, 2/August/2013
LHC Crab Cryomodule meeting

13. Geometrical constraints
SPS :
OC, 2/August/2013
LHC Crab Cryomodule meeting

14. Geometrical constraints
SPS :
OC, 2/August/2013
LHC Crab Cryomodule meeting

15. Geometrical constraints
SPS dummy beam pipe :
SPS configuration
LHC configuration
OC, 2/August/2013
LHC Crab Cryomodule meeting

16. Geometrical constraints
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
OC, 2/August/2013
LHC Crab Cryomodule meeting

17. Geometrical constraints
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
OC, 2/August/2013
LHC Crab Cryomodule meeting

18. Geometrical constraints
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
OC, 2/August/2013
LHC Crab Cryomodule meeting

19. Geometrical constraints
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
OC, 2/August/2013
LHC Crab Cryomodule meeting

20. Geometrical constraints
SPS interfaces:
Connexions to main coupler
From top, vertically
OC, 2/August/2013
LHC Crab Cryomodule meeting

21. Geometrical constraints
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
OC, 2/August/2013
LHC Crab Cryomodule meeting

22. Geometrical constraints
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 K
cryostat interface
CWT
Power coupler intercept
OC, 2/August/2013
LHC Crab Cryomodule meeting

23. LHC Crab Cryomodule meeting
Alignment
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
OC, 2/August/2013
LHC Crab Cryomodule meeting

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

25. Process & instrumentation
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
helium tank
crab cavity
common pumping collector
thermal screen at ~80 K
cryostat interface
CWT
Power coupler intercept
OC, 2/August/2013
See Krzysztof’s talk
LHC Crab Cryomodule meeting

26. Process & instrumentation
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
common pumping collector
thermal screen at ~80 K
cryostat interface
CWT
Power coupler intercept
OC, 2/August/2013
LHC Crab Cryomodule meeting

27. Process & instrumentation
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 collector
thermal screen at ~80 K
cryostat interface
CWT
Power coupler intercept
SKETCH LT PT EH TT
OC, 2/August/2013
LHC Crab Cryomodule meeting

28. Process & instrumentation
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
common pumping collector
thermal screen at ~80 K
cryostat interface
CWT
Power coupler intercept
SKETCH LT PT EH TT
OC, 2/August/2013
LHC Crab Cryomodule meeting

29. LHC Crab Cryomodule meeting
Piping sizing
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 92
100 mm
~90 mm
0 mm
Liquid level
~50 mm
Regulation
maxi: 5 m/s
* Calculation done assuming: collector diameter of 100 mm, He mass flow = 2 g/s, GHe temp = 2 K, GHe press = 20 mbar.
OC, 2/August/2013
LHC Crab Cryomodule meeting

30. LHC Crab Cryomodule meeting
Helium tank sizing
Helium tank to be dimensioned correctly to extract maximum heat load
Heat flux in He II depend on bath temp. and channel dimension
OC, 2/August/2013
LHC Crab Cryomodule meeting

31. LHC Crab Cryomodule meeting
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)
OC, 2/August/2013
LHC Crab Cryomodule meeting

32. LHC Crab Cryomodule meeting
Heat load budget
OC, 2/August/2013
LHC Crab Cryomodule meeting

33. LHC Crab Cryomodule meeting
Safety equipment
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);
OC, 2/August/2013
See talk of Luis
LHC Crab Cryomodule meeting

34. LHC Crab Cryomodule meeting
Safety equipment
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.
OC, 2/August/2013
LHC Crab Cryomodule meeting

35. LHC Crab Cryomodule meeting
Materials
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
OC, 2/August/2013
LHC Crab Cryomodule meeting

36. LHC Crab Cryomodule meeting
Magnetic shielding
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
OC, 2/August/2013
LHC Crab Cryomodule meeting

37. LHC Crab Cryomodule meeting
Cryostating
Integration into cryostat at CERN - most likely location SM18
OC, 2/August/2013
LHC Crab Cryomodule meeting

38. LHC Crab Cryomodule meeting
Concluding remark
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
OC, 2/August/2013
LHC Crab Cryomodule meeting