1. Cryo-assembly design
D. Ramos, V. Parma, C. Mucher, H. Prin, M. Souchet, J. Hrivnak, M. Moretti, L. Mora, F. Savary, L. Gentini
Review of the 11T Dipoles at Collimator Section for the HL-LHC

2. Outline Recalling the concept
Bypass cryostat and interfaces with collimator
Support layout and management of thermal contractions
Interconnect design
Interfaces with beam vacuum
Vacuum vessel specifications
Thermal shield design
Line N cable pulling
Instrumentation
Current leads
Drawings for management of mechanical interfaces

3. Cryo-assembly: 3 modules to replace one MB
Cryo-assembly composed of 3 independently aligned modules: 2 cryo-magnets + 1 bypass cryostat
Collimator mechanically decoupled from the cryostat
The cryo-assembly is interchangeable with any MB irrespective of location (see cold mass presentation for implications on circuits)
No changes required to nearby magnets

4. The integration approachK2 M2 V2 W Y M1 M3 E C’ V1 K1 X N
QRL side

5. X Y M2 M1 W M3 E N C’ Cold beam line Dedicated collimator design.
One collimator design fits both beam lines W
Collimator alignment is not impacted by vacuum vessel displacements during pump down M3 E N
Collimator supported directly on the concrete slab C’

6. Bypass cryostat Installed before the collimator
Creates a room temperature vacuum sector in the continuous cryostat
Aligned as any other machine cryostat

7. TCLD Collimator - Interfaces
Courtesy L. Gentini
TCLD Collimator - Interfaces
New design of actuation system in order to comply with integration constraints
‘Quick’ CF flange for removal and connection of collimator
Pre-aligned support stand
Integrated expansion joint with RF bridge
for alignment and installation clearance
Jaw “active” length: 600 mm
Flange to flange length: 1080 mm

8. Cryostat support layout
Cold mass fixed point near the centre:
for small contractions at the intermediate interconnects and
minimum change wrt replaced MB
Distance between jacks shared with DS magnets Q11, Q10, Q8: 3705 mm
Gives nearly ideal cold foot distance for minimum cold mass deformation: 3430 mm (estimated less than 0.1 mm sag even with a 10 mm thick shell)
W-sleeve on the downstream interconnect cannot be fully open but still acceptable for interconnecting work

9. Interconnecting the 11 T cold masses
Universal expansion joints between cold masses:
Negligeable interconnect forces
No static heat loads through supports
Line X
Lines M1, M2
Line N
CWT
Line E
Line V

10. Expansion joint design
Busbar line M universal expansion joint
Heat exchanger line X universal expansion joint (external)
Thermal shield line E universal expansion joint
Aux. busbar line N universal expansion joint
Design pressure [bar]
20  4 22
Test pressure [bar] 25
5.2
27.5
Temperature [K]
300 – 2
300 – 50
Axial displacement [mm]
16 (-6/10)
23 (-8/15)
30(-10/20)
Inner diameter [mm] 88
54.4 80 50
Outer diameter [mm]
101
73.4
99.5 70
Convolution pitch [mm]
9.1
4.47
6.52 9
Number of convolutions
4+4
6+6
Number of plies 3 2
Thickness of on ply [mm]
0.4
0.3
0.35
Axial stiffness [N/mm]
504
124
285
172
Column squirm pressure (EN 13445) [bar] 77 37 39 24
In-plane squirm pressure (EN 13445) [bar] 66 19 49 29
Fatigue life (EN 13445) [cycles]
686
623
467
192
Fatigue life (EJMA) [cycles]
2065
1875
1404
579
Circumferential membrane stress [MPa] 31 5 28
Meridional membrane plus bending combined stress [MPa]
135 89
198
214
Stainless steel (316L)
Proof stress Rp1.0 [MPa]
260
Allowable circumferential stress f=Rp1.0/1.5 [MPa]
173
Allowable meridional stress Kf.f [MPa]
520
See Edms doc

11. Cold to wam transition and cold beam line
Supplied and assembled by TE-VSC
Compact design
Copper cold bore, conduction cooled
1.9 K Thermalisation at the extremities
85 mW to 1.9 K level
See Q. Deliege, WG Meeting on Cryostats for HL-LHC magnets #8,
Heat loads for 2 CWT’s:
~ 5.5 W to 5 K level
< 12 W to K level

12. Vacuum vessel for cryo-magnet
See technical specification LHC-QBAH-CI-0001, Edms doc
Cylinder: P355NL2 low carbon carbon steel with impact tests at -50 C
Flanges: (304L) stainless steel
Vibration stress relieving after welding followed by precision machining of interfaces
Abrasive blasting plus high pressure water jet degreasing
Leak tightness 10-9 Pa m3 s-1
Painted external surfaces for corrosion protection
Reguirements identical to present LHC cryostats

13. Vacuum vessel for bypass
The same vacuum vessel can be used for collimator either on beam 1 or beam 2
Stainless steel (304L) stainless steel
Vibration stress relieving after welding followed by precision machining of interfaces
Abrasive blasting plus high pressure degreasing
Leak tightness 10-9 Pa m3 s-1
Mechanical analysis: J. Hrivnak, WG meeting on cryostats for HL-LHC magnets #6,

14. Thermal shield bottom tray and cold support posts
See drawing folder Edms doc
Sliding support post bolted to the cold mass and guided on vacuum vessel with alignment key
Fixed support post bolted to the cold mass and to the vacuum vessel
Standard aluminium to stainless steel transitions
Stainless steel piping
Using existing extruded aluminium extrusions
GFRE support posts available in stock
Standard C’ line pipework

15. Thermal shield Two cooling points at the extremities
Thermal shield for bypass cryostat made from AW 1050
Welding during assembly excluded due to risk of fire on MLI: Bolted assembly with invar washers
End plates supported on three slotted holes at 120º to accomodate radial thermal contraction
Downstream plate supports with play for axial thermal contraction
Thermalisation to line E at two points
Thermal shield in the 11T cryo-magnets and interconnects are identical to MB cryostats
Heat load to K [W]
Thermal shield support 18
V-line support
1.3
Radiation
8.7
Total 28
See H. Hrivnak, WG Meeting on Cryostats for HL-LHC magnets #10,
Two cooling points at the extremities

16. Pulling of line N cable
New line N routing adds two bends as it goes through the bypass cryostat
50 m long cable pulling test was performed on a full scale mockup to ensure feasibilty in the tunnel
Feasibility demonstrated: No additional splices required. Temporary tooling necessary at the interconnect flanges to prevent metal edges from damaging the cable insulation

17. Instrumentation
Two IFS connector boxes for cold mass instrumentation (see cold mass presentation)
IFS boxes of existing LHC design
Thermometers for cold tests:
Line E (lowest temperature)
Bypass thermal shield (highest temperature)
4x DN100 KF for feedthroughs on prototype vacuum vessel
No thermometers on machine cryo-assemblies

18. Current leads for the trim circuit
2x 250 A conduction cooled leads
Only one location is possible
Similar to a Dipole Corrector Feedthrough in the SSS (EDMS )
RT copper cables  towards power converter
Gas cooled leads not possible both for lack of space and cryogenics
Preference for conduction cooled leads
Local solution: applicable everywhere in the LHC

19. Mechanical interface layout

20. Jack positions in the tunnel
Longitudinal constraint
Lateral constraint

21. Handling and transport interfaces

22. Conclusion
Integration with magnet, collimator and vacuum has been concluded.
The design of the prototype cryostat is done. Assembly drawings and procedures are being drafted.
The design of the bypass cryostat is nearly finished.
The magnet cryostats follow the LHC design basics.
One configuration designed to fit all possible locations in the LHC (with local trim).
No changes required to nearby magnets.
Interconnecting work done in the tunnel takes advantage of existing procedures thanks to many LHC standard components and tooling.

24. A. Lechner et al. - 3rd HiLumi LHC-LARP Meeting – Daresbury, Nov. 2013
Integration in IR7
A. Lechner et al. - 3rd HiLumi LHC-LARP Meeting – Daresbury, Nov. 2013