1. LCLS-II Cryomodule Design
Joshua Kaluzny, Yuriy Orlov, Tom Peterson
6 June 2014

2. LCLS-II Cryomodule Overview
Outline
Documentation list
Design methodology and basis
Cryomodule configuration
Thermal and fluid dynamic design
System interfaces and integration
Mechanical design
ES&H
Risks
Some long-lead procurements
Schedule
6/6/14
LCLS-II Cryomodule Overview

3. Documentation https://indico.fnal.gov/conferenceDisplay.py?confId=8598
SCRF 1.3 GHz Cryomodule Physics Requirements Document (PRD) (LCLS-II document number: LCLSII-4.1-PR-0146-R0)
SCRF 1.3 GHz Cryomodule Functional Requirements Specification (FRS) (LCLSII-2.5-FR-0053)
Cryogenic System – Cryomodule Design Methodology (LCLS-II engineering note #LCLS-II-4.5-EN-0186)
Cryogenic Distribution System Interface Control Document (draft) (Title: Cryogenic Distribution System; Document Number: LCLSII-4.9-IC-0058-R0)
Cryomodule Comparison, Including LCLS-II Design and Options
Cryomodule helium volumes (LCLS-II-CryomoduleVolumes-18Apr2014.xls)
Heat load estimate documents
LCLS-II Cryogenic Heat Load 22May2014 (summary MS Word document)
LCLScryoHeat-22May2014 (Excel spreadsheet analyses and tabulation of total heat loads)
1.3 GHz Cryomodule 2-dimensional assembly drawings
Process and Instrument Diagram (P&ID)
Draft Schedule for LCLS-II Preproduction Module-v11
6/6/14
LCLS-II Cryomodule Overview

4. LCLS-II Cryomodule Overview
Linac
Figure from Physics Requirements Document: SCRF 1.3 GHz Cryomodule
Document Number: LCLSII-4.1-PR-0146-R0
4/30/2014 Original Release
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LCLS-II Cryomodule Overview

5. LCLS-II Cryomodule Overview
Cryogenic System
Figure from
Interface Control Document:
Cryogenic Distribution System
Document Number:
LCLSII-4.9-IC-0058-R0
Draft (June 5, 2014)
6/6/14
LCLS-II Cryomodule Overview

6. Design Methodology and Basis
High heat loads result in
Larger chimney pipe from helium vessel to 2-phase pipe
Larger 2-phase pipe (~100 mm OD) for low velocity vapor flow
Both high heat load and the 0.5% slope of the SLAC tunnel require
Closed-ended 2-phase pipe providing separate 2 K liquid levels in each cryomodule
2 K JT (liquid supply) valve on each cryomodule
Two layers of cold magnetic shielding to preserve high Q0
Minimal df/dP and tuner design refinements result in our selection of end lever tuner and associated helium vessel design
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LCLS-II Cryomodule Overview

7. Design Methodology and Basis -- more
Addition of access ports for maintenance of tuners
Enabled by new tuner design
Access also to piezos
Access on SLAC tunnel wall side, but most likely need during tests
Uniform cool-down of bimetal joints at each end of the cavity by means of two cool-down ports in each helium vessel
No 5 K thermal shield, a simplification due to large dynamic heat at 2 K making such a thermal shield of marginal value
But retain 5 K intercepts on input coupler
Input coupler design for 7 kW CW plus some margin
A modification of an existing pulsed coupler design involving better heat transfer from and cooling of the inner conductor
Enhanced cooling of HOM couplers
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LCLS-II Cryomodule Overview

8. TESLA/LCLS-II line designations
2.2 K subcooled supply
Gas helium return header, structural support
5 K thermal intercept supply
5 K thermal intercept return
High temperature shield and intercept supply
High temperature shield and intercept return
2-phase pipe
Warm-up/cool-down line
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LCLS-II Cryomodule Overview

9. Cryomodule configuration
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LCLS-II Cryomodule Overview

10. LCLS-II cryomodule cross-section at liquid fill valve
Line A
Line B
Line C
Line F
Line E
Line D
Line G
Line H
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LCLS-II Cryomodule Overview

11. TESLA-style cryomodules compared - 1
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LCLS-II Cryomodule Overview

12. TESLA-style cryomodules compared - 2
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LCLS-II Cryomodule Overview

13. LCLS-II Cryomodule Overview
Helium inventory
Each dressed cavity – 27 liquid liters
8 dressed cavities – 214 liquid liters
Pipes – 134 liquid liters equivalent mass
One cryomodule total – 348 liquid liters equivalent
LCLS-II cryomodules – 13,000 liquid liters equivalent
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LCLS-II Cryomodule Overview

14. LCLS-II Cryomodule Overview
6/6/14
LCLS-II Cryomodule Overview

15. Thermal and fluid dynamic design
Heat loads around 80 – 150 W per cryomodule at 2 K
Depending on local HOM deposition and also on cavity Q0, a cavity may see as much as 25 W
Due to the 0.5% slope
6 cm elevation difference over 12 m
10 cm dia 2-phase pipe is nearly full at one end, nearly empty at the other end
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LCLS-II Cryomodule Overview

16. Cryomodule static heat loads
From LCLScryoHeat-22May2014.xlsx (posted as a supplemental document)
The most thorough measurements have been done at DESY for XFEL and at KEK for S1-Global.
Good agreement, but S1-Global was a bit odd, consisting of two 4-cavity CM’s welded together
Used the XFEL conclusion plus a bit more for the addition of a valve
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LCLS-II Cryomodule Overview

17. 2 K heat in first few cryomodules
From LCLScryoHeat-22May2014.xlsx (posted as a supplemental document)
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LCLS-II Cryomodule Overview

18. LCLS-II Cryomodule Overview
Heat load references
For a description of assumptions and methods, and a list of references, see:
SLAC Engineering Note: LCLS-II Cryogenic Heat Load, Note Number: LCLSII-4.5-EN-0179, Date: 22 May 2014
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LCLS-II Cryomodule Overview

19. “Chimney” heat transport
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LCLS-II Cryomodule Overview

20. Connection diameter versus heat flux
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LCLS-II Cryomodule Overview

21. Sloped liquid surface in 2-phase pipe
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LCLS-II Cryomodule Overview

22. 5 meter/sec speed limit for vapor over liquid sets 2-phase pipe size
XFEL takes a limit
of 20 W per
cryomodule
XFEL
XFEL
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LCLS-II Cryomodule Overview

23. Cryomodule pipe pressures
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LCLS-II Cryomodule Overview

24. System interfaces and integration
Meetings with SLAC (web/phone connections) include an “LCLS-II Cryomodule Mechanical Integration Meeting” (currently every other week) hosted by Ginger DeContreras with attendees from Fermilab, Jlab, and SLAC
Topics: tunnel constraints, interfaces, instrumentation, and cryomodule integration into the larger linac system
Frequent meetings and close collaboration with cryogenic distribution effort (in Accelerator Division Cryogenics Department at Fermilab)
Overall flow rates and pressure drops, emergency venting, line sizing, cryogenic controls
Weekly meetings and communication with Jlab cryogenic plant and cryomodule designers
Cryomodules, cryogenic distribution, and cryogenic plant together make up the cryogenic system, which must be treated as an integrated design
Jlab personnel not only partner with us for procurement and fabrication of the 1.3 GHz cryomodules but have extensive experience in cryomodule fabrication and operations
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LCLS-II Cryomodule Overview

25. Cryomodule in SLAC tunnel Ginger DeContreras and Henry Alvarez, SLAC
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LCLS-II Cryomodule Overview

26. LCLS-II Cryomodule Overview
P&ID
See drawing LCLS-II Cryomodule P&ID (F ) posted at
And I’ll show a draft Instrumentation List (not posted yet, but will be soon)
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LCLS-II Cryomodule Overview

27. Cryogenic System Design
From LCLScryoHeat-22May2014.xlsx
(posted as a supplemental document)
6/6/14
LCLS-II Cryomodule Overview

28. LCLS-II Cryomodule Overview
Above table is best estimate of heat loads,
no margins or safety factors.
From: SLAC Engineering Note: LCLS-II Cryogenic Heat Load
Note Number: LCLSII-4.5-EN-0179 Date: 22 May 2014
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LCLS-II Cryomodule Overview

29. LCLS-II Cryomodule Overview
Above table includes uncertainty factors of:
1.3 for all static heat loads
1.1 for all dynamic heat loads.
From: SLAC Engineering Note: LCLS-II Cryogenic Heat Load
Note Number: LCLSII-4.5-EN-0179 Date: 22 May 2014
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LCLS-II Cryomodule Overview

30. LCLS-II Cryomodule Overview
System Pressure Drops
Pressure drops must be analyzed for each helium flow path to ensure that steady-state operation matches system design and that non-steady conditions (cool-down, emergency venting, warm-up) are properly handled
Input variables include line size,
Allowable temperature rise,
Allowable pressure drop
Heat load (temperature rise and heat load  mass flow)
Maximum allowable pressure for emergency venting
Matching cryomodule/distribution system to the cryogenic plant
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LCLS-II Cryomodule Overview

31. System Pressure Drop Analysis Status Update (Joshua Kaluzny)
Line
Pressure Drop Analysis
Relief Analysis
Low Pressure Gas Return Pipe (Line B)
Advanced
In Progress
Low Temperature Thermal Intercept (Line C,D)
Preliminary
High Temperature Thermal Shield (Line E,F)
Helium Supply (Line A)
Warm-up/Cool-down (Line H)
Line analyses include cryogenic distribution system
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LCLS-II Cryomodule Overview

32. High Temperature Shield Mass Flow and Pressure Drop
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LCLS-II Cryomodule Overview

33. GRP Temperature and Pressure Distribution
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LCLS-II Cryomodule Overview

34. A quick look at mechanical design
Spacings set to even wavelengths
6 lambda cavity slot length
53 lambda cryomodule slot length (12220 mm)
In accordance with SLAC “MAD Deck”, a spreadsheet of linac element positions used for beam dynamics design and analysis
Structure is basically TESLA/Type 3+/XFEL, except
Isolation of 2-phase line
Addition of JT valve
Tuner motor access ports
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LCLS-II Cryomodule Overview

35. LCLS-II Cryomodule Overview
LCLS-II. Y-Z Section
(See ED Master Spreadsheet 1.3GHz CM LCLS-II for linear dimension)
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LCLS-II Cryomodule Overview
~12220

36. LCLS-II Cryomodule Overview
LCLS-II. Y-X Section
He Internal Pressure:
4 bar-cold
2 bar-warm
32.5
Tuner motor
access port’s
389
167.2
356
Tuner motor
access port
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LCLS-II Cryomodule Overview
233
(2-Phase Pipe location)

37. LCLS-II-Cold Mass Upstream End
Upstream Gate Valve
End Level tuner
Upstream He level
Warm up cool down line
2-Layer cavity magnetic shields
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LCLS-II Cryomodule Overview

38. LCLS-II- Cold Mass Downstream End.
GV support
Downstream GV
Warm Up cool
down line
Quad bearing supports
Splittable Quad
Reentrant BPM
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LCLS-II Cryomodule Overview

39. LCLS-II preproduction Level Tuner.
Interconnection magnetic shield (2-layers)-not shown
Beam Pipe interconnection Bellows
Level Tuner
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LCLS-II Cryomodule Overview

40. LSLC-II CM Interconnection
850mm
~700mm
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LCLS-II Cryomodule Overview

41. LCLS-II Cryomodule Overview
ES&H
Pressure vessels, piping, ODH
Helium vessel around the cavity is the pressure vessel
Piping must all meet pressure piping standards
Fermilab ES&H manual section 5000 includes cryogenic system safety, pressure vessel standards, SRF dressed cavity standard, vacuum vessel standard, oxygen deficiency hazards (ODH), etc.
SLAC, Fermilab, and Jlab will agree upon a common set of standards based on these and those at the partner labs
Seismic analysis
Fermilab will perform mechanical analyses of a cryomodule assembly under various acceleration and/or oscillatory modes as required by SLAC
These are also needed for design for shipping
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LCLS-II Cryomodule Overview

42. LCLS-II Cryomodule Overview
Documentation in addition to previously mentioned engineering documents
Fermilab-style safety engineering notes
Dressed cavity helium vessels. Demonstrates compliance with pressure vessel rules.
Piping engineering note. Demonstrates compliance with pressure piping rules.
Vacuum vessel engineering note. Demonstrates compliance with vacuum vessel rules.
Piping mechanical loads and stability
Static piping pressure loads, support structure stresses, and interconnect stability
Dynamic analyses for shipping and seismic issues
Various other documents verifying design and interfaces
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LCLS-II Cryomodule Overview

43. Selected Risks (from Risk Table)
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LCLS-II Cryomodule Overview

44. LCLS-II Cryomodule Overview
Tuner access ports
Cornell ERL injector cryomodule successfully incorporated access ports
Allow access to tuner motor, drive mechanism, and piezos without pulling the cavity string out of cryostat.
Fermilab tuner is designed to allow access to critical components via access ports
Ports must be on opposite side from input couplers, which is the wall side in the SLAC tunnel
Ports available during initial CMTS tests
Ports would not enable access to Saclay tuner
Definitely include access in prototype cryomodules
These will incorporate Fermilab tuner
Mitigates risk of problems with new tuner design
Include access ports in production cyromodule?
Decision based on cost / risk analysis following initial tuner tests in HTS.
Assemble a mechanical mock-up including thermal shield and MLI to check access port utility.
6/6/14
LCLS-II Cryomodule Overview

45. Heat loads and cryogenic plant size
Heat loads are carefully evaluated
Input from various groups including beam dynamics, RF cavity performance, input couplers, cryomodule design, magnets and current leads, distribution system
These are tabulated as “best estimates” meaning no margin added. These are the expected values
Then also an uncertainty factor must be applied
Heat load x uncertainty factor = maximum anticipated
Uncertainty factor evaluation should be quantitatively based on measurements and statistics
These then provide input to the cryogenic plant design and sizing
Temperature and pressure constraints agreed upon by various cryogenic system designers provides additional input
Combinations of heat loads (e.g., static only, static +RF, static + RF + beam) provide various “modes” for cryogenic plant operation
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LCLS-II Cryomodule Overview

46. LCLS-II Cryomodule Overview
Conclusion
Very good TEAM effort including with partner labs
Emphasis on system design
Deviations from previous TESLA-style cryomodules are necessary, but structure and form are very much the TESLA concept
Significant effort and tight schedule
6/6/14
LCLS-II Cryomodule Overview