1. Summary of WG2: Design and Fabrication of Cavities and Cryomodules
A total of 25 talks were presented
- XFEL Activities
- Infrastructure overview
- Coupler business
- PED pressure vessel codes
- Low beta design issues for cavities and modules
It is impossible to show every highlight in the summary.
Please excuse us if one or the other highlight is not mentioned or missing. Its hard to extract all essential information and highlights for a short presentation summary !
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary

2. TTC - Milano WG-2 Summary
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary

3. TTC - Milano WG-2 Summary
Preparation for XFEL/1
The infrastructure layout for the cavity fabrication plants at vendors (Zanon and RI), and for the cryomodule assembly plant at CEA-Saclay
Construction of the cavity plants, procurement of equipments (clean room, furnace, BCP, etc...) are underway.
Warm RF test/tuning machines provided by DESY.
CEA plant is in commissioning phase with 2 proto-XFEL modules
First XFEL cavities are expected by mid-2012.
Nb and NbTi material is procured by DESY to 4 vendors worldwide.
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary

4. TTC - Milano WG-2 Summary
Preparation for XFEL/2
The FLASH 3.9 GHz module built by FNAL is in operation at nominal gradient, and has already generated short bunches.
Success story
Starting from that, now the construction of the XFEL 3.9 GHz cavity prototypes and of the 8 cavity module, is under the responsibility of INFN-Milano.
Prototypes are close to testing stage and the XFEL 3H system design is being finalized and on the way to procurement.
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary

5. TTC - Milano WG-2 Summary
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary

6. TTC - Milano WG-2 Summary
Infrastructures
CERN plans to refurbish existing infrastructure for various projects including continuing SPL cavity and cryomodule development work (also LHC/ISOLDE/CLIC)
University of Wuppertal, Germany
DC Field Emission Scanning Microscopy on Nb Samples
High Resolution SEM/EDX for Field Emitter Identification
Surface Roughness Measurements with OP/AFM on Nb
“New” Infrastructure at Saclay (not only XFEL, long range roadmap (Spiral2, IFMIF, ESS…, R&D topics)
Refurbishment/upgrade of existing infrastructures at DESY/JLAB (TEDF)/KEK (Pilot Plant)
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary

7. TTC - Milano WG-2 Summary
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary

8. Mircea Stirbet, Power Coupler cleaning
SNS Power coupler as an example :
The FPC cleaning should start at the design stage
Adequate infrastructure
Trained personnel
The importance of meticulously cleaning the power coupler before it is installed on a clean SRF cavity is widely accepted A B
A- FPC initial concept welded outer conductor impact on cleaning!!!
B - FPC prototype independent outer conductor
Everybody takes the QC very seriously! BUT….
28 Feb - 3 Mar 2011

9. But: we see unexpected damage after operation (not found during acceptance QC)
Is our inspection sufficient? D. Kostin, M. Champion
28 Feb - 3 Mar 2011

10. TTC - Milano WG-2 Summary
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary

11. TTC - Milano WG-2 Summary
WG 2 Part Pressure vessel certification and Cryomodule Design contributed talks
Pressure vessels codes
3 different approaches presented to find local solutions
KEK Definition of pressure vessel = Cavity without 2 Phase line
 simplified rules
FNAL adopted to legal Department of Energy rules, Lab internal codes, and regulations
DESY Co working with the notified body
Next stage would be to address the international exchange of components concerning PV requirements
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary

12. TTC - Milano WG-2 Summary
KEK Definition of pressure vessel
Advantages with the Category of Ordinal Device at PV < 0.004
Process and inspection with HP code simplified
Material mechanical evaluation prior to production process required,
HP code test (Pressure, and leak test) only required in the completion process,
Subject for further investigation
If the 2–phase pipe to be included in the cavity category or to be included in the cryomodule?
Can we convert material at the boundary; Ti to SUS (including joint).
Akira Yamamoto and Eiji Kako
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary

13. TTC - Milano WG-2 Summary
Arkadi Klebaner 
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary

14. TTC - Milano WG-2 Summary
PED handling of the DESY/ XFEL cavities
Way for DESY to cover PED regulations
- Operational experiences over 15 years
- About 160 cavities build  long term experiences in cold operation
- Experiences on pressure + crash 2K on Cavity C 26 and Module 3*
- Traceability of drawings, fabrication, materials and preparation
DESY is defined as the manufacturer
- Fabricate a “test piece” (pre production welding test acc. to ISO 15613)
for destructive tests
- Manufacture n Cavities with notified body on place and do non destructive
testing on them (DCV - RCV cavities for XFEL Cavity production)
- Set up PMA material for materials (as in use) and follow this PMA strictly!
(PMA= Particular Material Appraisal Acc. PED(97/23/EC) annex I, Sec 4.2)
- Perform a pressure test on completed cavity for each cavity build
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary 14

15. ERL cryomodule systems
KEK -- construction of cERL Injector Cryomodule.
Work includes development and testing of prototype cavities, input couplers, HOM couplers, and a slide-jack frequency tuner. These components have been integrated into a cryomodule design, and a cryostat is under fabrication.
STFC -- An international collaboration was initiated in early 2006 with the goal to fabricate a new CW ERL cryomodule and validate with beam, dimensioned to fit on ALICE.
Work includes cavity devepment and testing, tuner (Saclay type-II) modification and development, input coupler and HOM absorber development and testing, and development of a cryogenic heat exchanger system for providing new levels of thermal shield cooling.
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary

16. ERL cryomodule systems (continued)
Cornell -- An ERL injector prototype has been developed, fabricated, and is currently under commissioning.
Design work on the main linac cryomodule has started. Work includes Cavity support and alignment, magnetic shielding for high Q0, considerations for cryogenics and thermal shield and thermal intercept cooling with very high heat loads, and microphonics. Design features were compared to FLASH/XFEL modules.
JINR -- In 2006, JINR (Dubna, Russia), VNIIEF (Sarov, Russia), INFN (Pisa, Italy), and FNAL (Batavia, USA) established a collaboration upon the initiative of the JINR and started joint activities on the ILC.
Work includes R&D on bimetallic transitions, cavity interconnect development, precision long-distance laser metrology, and SRF cavity work. In 2007 the JINR officially joined the ILC Project and proposed the Dubna region for the ILC location.
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary

17. TTC - Milano WG-2 Summary
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary

18. TTC - Milano WG-2 Summary
Low Beta design issues
IFMIF SC HWR Cryomodule Development F.ORSINI (CEA)
Impressive CW beam specs (125 mA D+)
Cavity package/cryom. using novel solutions (e.g. tuner)
Unfortunately cavity not yet completely to specs, interesting to hear at next TTC meeting
Low beta cryomodule developments at FNAL Tom Nicol (FNAL)
Engineering towards prototyping of Project X modules
Main project choices
SC linac since 2.5 MeV!
Choice of “fine segmentation” of modules
2 K operation (even at the moderate frequency of the low energy end)
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary

19. TTC - Milano WG-2 Summary
Low Beta design issues
Plans for CERN SPL Test Cryomodule Wolfgang Weingarten (CERN)
Design of a short 4-cavity b=1 cryomodule for SPL
Still in conceptual stage in many areas, moving to engineering
Main motivation is RF-test stand for cavities fed by single or multiple RF source (SPL design)
Cavity is supported by coupler
Spiral 2 Cavities and Cryomodule Tests Guillaume Olry (IPN)
Very good VT performances according to specs for gradient and field emission onset
After 2 module assemblies performance deteriorated
Evidence of spots and scratches on cavity and antenna surfaces after inspection
Please share the findings and conclusions at next TTC meeting!
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary

20. TTC - Milano WG-2 Summary
Conclusions
SRF technology is gaining maturity in a diversified environment
We would like to hear more about cavity and cryomodule design, test, and operational experience at the next TTC
All types of cavities and cryomodules -- e-, proton/H-, heavy ion, ERL
Various design concepts
Assembly and operational experience
28 Feb - 3 Mar 2011
TTC - Milano WG-2 Summary