1. CERN SPL Fundamental Power Coupler Progress report
SPL meeting
CERN, December 2012
Eric Montesinos, CERN BE-RF-PM

2. Contents Introduction SPL coupler project Next steps Key R&D results :
SPL meeting, CERN
5-6 December 2012
Contents
Introduction
CERN RF Fundamental Power Coupler team
SPL coupler project
SPL FPC initial design proposals
March 2010 Coupler review
June 2010 SPL Coupler project
Construction
Assembly in DESY clean room
Double walled Tubes (DT)
LLRF tests
High Power tests at CEA : TW
High Power tests at CEA : SW
Next steps
Key R&D results :
Mono bloc waveguide
Test box
Double walled Tube as support for cavity
High Average power air cooled couplers

3. CERN RF Fundamental Power Coupler team
SPL meeting, CERN
5-6 December 2012
CERN RF Fundamental Power Coupler team
CERN Machine
Design
Prototype
Series
SPS 200
2001
LHC 400
2006
Linac 4
Under Way
SPL cylindrical
Under test
SPL planar
HIE-Isolde
Crab Cavities
To come
SPS 800
LIU- SPS 200
SPS 200 MHz coupler
LHC 400 MHz coupler
Linac 4
352 MHz coupler
SPL 704 MHz couplers
HIE Isolde 100 MHz couplers

4. CERN RF Fundamental Power Coupler team
SPL meeting, CERN
5-6 December 2012
CERN RF Fundamental Power Coupler team
Machine
Design
Prototype
Tests
ESRF
300 kW CW
ANL-APS
100 kW CW
SOLEIL
Under way
SOLEIL 352 MHz coupler design
ESRF 352 MHz coupler
Argonne APS 352 MHz coupler

5. SPL FPC initial design proposals
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
SPL FPC initial design proposals
RF Characteristics f0
704.4 MHz
Power levels
1000 kW pulsed
= 2.0 ms
50 Hz (20 ms)
100 kW average
Cavity design gradient
19-25 MV/m
Qext of input coupler
1.2 x 106
Input line Ø
100 / 43.5 mm = 50 Ω
(from the cavity design)
Waveguides
WR 1150
Cylindrical
Window
CEA HIPPI
(baseline)
Disk
Coaxial
window
Disk WG
Window

6. SPL FPC initial design proposals
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
SPL FPC initial design proposals
Window-Ceramic-Antenna
275 Series 4-8 MCHF
Baseline: CEA Saclay coupler
To be upgraded for SPL cryomodule compatibility
Kept open the possibility to use another design, to be fixed in March 2010
Comparison basis:
RF power capability
Low heat load
Tuning capability (fixed coupling, adjustable coupling)
Conditioning time
Contamination during beam part assembly
Easy installation
Integration with the cryomodule
Easy operation
Cost
15 kCHF
4.125 MCHF
30 kCHF
8.25 MCHF
14 kCHF
3.85 MCHF
15 kCHF
4.125 MCHF

7. March 2010 Coupler review Review committee members : Presenters :
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
March 2010 Coupler review
Review committee members :
Ali Nassiri (Chair)
Wolf Dietrich Moeller
Mark Champion
Sergey Kazakov
Mircea Stirbet
Presenters :
Amos Dexter & Rama Calaga (Multipacting simulations)
Miguel Jimenez (Vacuum)
Sergio Calatroni (DT Coating)
Ofelia Capatina & Vittorio Parma (Cryomodule integration)
Eric Montesinos (FPC)
Technical Choices
Single window coupler
Fixed coupler
With a Double Walled Tube
Mounted in clean room with its double walled tube horizontally in only one operation
Vertically below the cavity and will be a support for the cavity (first time worldwide)
With a HV DC biasing capacitor
Air cooled

8. Two designs have been validated
SPL meeting, CERN
5-6 December 2012
Two designs have been validated
Cylindrical
ceramic window
Coaxial disk
ceramic window

9. Same Waveguide with integrated matching step (instead of a doorknob)
SPL meeting, CERN
5-6 December 2012
Same Waveguide with integrated matching step (instead of a doorknob)
And same DC capacitor
Same Double Walled Tube
(Outer line of a coaxial transmission Line)
With same interface flange
to cryomodule

10. Cylindrical window Advantages Drawbacks
SPL meeting, CERN
5-6 December 2012
Cylindrical window
Advantages
LHC window with high power capability due to its solid copper collars
Simple to cool down with air
Absolutely free of mechanical stress onto the antenna
“plug and play” waveguide and DC capacitor, no stress to the ceramic
Drawbacks
Ceramic is part of the matching system, imposing the waveguide position

11. Coaxial Disk window Advantages Drawback
SPL meeting, CERN
5-6 December 2012
Coaxial Disk window
Advantages
Very simple and well mastered brazing of ceramic onto a titanium flange
Simple to cool down with air
“plug and play” waveguide and DC capacitor, no stress to the ceramic
Drawback
Ceramic is part of the matching system, fixing the waveguide position

12. SPL coupler project (June 2010)
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
SPL coupler project (June 2010)
Four vacuum lines:
4 cylindrical window couplers
4 disk window couplers
8 Double walled Tubes
4 test boxes
DESY clean process assembly
(Jlab also proposed to help)
CERN LLRF measurements
CEA RF power tests
(BNL also proposed to help)

13. Couplers construction
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
Couplers construction
All parts have been produced by May 2011 (10 months)
All components have been individually vacuum leak free tested before being sent to DESY for assembly

14. Couplers construction
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
Couplers construction
All parts have been produced by May 2011 (10 months)
All components have been individually vacuum leak free tested before being sent to DESY for assembly
Specific transport boxes with springs as per tetrodes have been designed to avoid any shocks

15. Assembly in DESY clean room
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
Assembly in DESY clean room
In June 2011, the four cavities were assembled in DESY clean room
Use of a specially designed helicoflex seal

16. Assembly in DESY clean room
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
Assembly in DESY clean room
In June 2011, the four cavities were assembled in DESY clean room
Use of a specially designed helicoflex seal
Thanks to DESY colleagues who have performed a very good job and to a very good preparation job of the jointing surfaces all four cavities were leak free

17. Double walled Tube (DT)
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
Double walled Tube (DT)
Copper sputtering removed with simple water Ultra Sonic cleaning process
Mistake in the machining process :
An additional machining step not included in the lists has erased all the care put into the preparation of DT
Decision to continue the first two vacuum lines with NOT copper sputtered DT :
Lead into a very important delay onto the schedule
Will limit average power during tests

18. LLRF measurements at CERN (summer 2011)
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
LLRF measurements at CERN (summer 2011)
S11 with 2 x N/WG adaptors + 2 couplers + 2 DT + test box :
Cylindrical windows = dB
Coaxial planar disk = -18 dB
Pfwd/Prev (S11) at CEA premises with 2 couplers + 2 DT + test box :
Cylindrical window = -17 dB
Coaxial planar disk = -40 dB
Even with only -16 dB, 1 MW will reverse 25 kW, acceptable with CEA premises, thanks to their circulator

19. RF power tests at CEA cylindrical window
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
RF power tests at CEA cylindrical window
First test were to check RF, so No bake out to take no risk with the test box helicoflex gasket
Static vacuum ~ 2 x 10-7 mbar
Pulse mode process
After 3 weeks, 50 kW 20 µs Hz
We Stopped the test

20. RF power tests at CEA disk windows
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
RF power tests at CEA disk windows
In the meantime, second test box with two disk window couplers has been baked out at CERN
No helicoflex leak
Very slow heating up and heating down ramps 10 C / hour
Maximum temperature during 48 hours was only 150 C
Nitrogen onto copper rings to avoid any oxidization
Very good static vacuum after the process ~ 1 x mbar (vs 5 x 10-7 mbar before starting the bake out)
Pulse mode process
After two weeks :
1000 kW 2 ms - 20 Hz
Ultimate goal of 1000 kW 2 ms Hz was not possible due to losses in uncoated DT limitation

21. RF power tests at CEA cylindrical window
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
RF power tests at CEA cylindrical window
We also baked out the first test box with two cylindrical windows at CERN
No helicoflex leak
Very good static vacuum after the process ~ 1 x mbar (vs 2 x 10-7 mbar before starting the bake out)
Pulse mode process
After 1 week:
1000 kW 2 ms - 20 Hz
Ultimate goal of 2 ms - 50 Hz was not possible due to losses in uncoated DT limitation

22. SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
TW tests ok (May 2012)
Both coupler versions have reached TW maximum values of 1 MW 2 ms - 20 Hz
Limitation of average power to 20 Hz instead of 50 Hz due to uncoated TD
Successful TW tests

23. SW tests with cylindrical window
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
SW tests with cylindrical window
A variable short circuit has been designed and constructed at CERN for SW test
Steps of 20 mm to have enough accuracy performing tests within all phases

24. SW tests with cylindrical window
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
SW tests with cylindrical window
We started SW tests in pulse mode
With 500 µs – 8Hz :
Up to 500 kW, no trouble
Arcing when reached 575 kW
It seemed to be air side as there was no vacuum activity
There was no arc detector to stop the test, a photomultiplier modulated RF, and it was possible to hear arcing in the WG system

25. SW tests with cylindrical window
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
SW tests with cylindrical window
Air side arcing were confirmed when dismounting WG
Input coupler presented some impressive arcing traces
Output coupler was without any trouble

26. SW tests with cylindrical window
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
SW tests with cylindrical window
Analyzing black deposit, we only identified :
Gold coming from upper gold platted copper collar
Copper coming from lower copper collar
There were without any doubt electrical arcing (>1’000) between two copper brazed collars
The only positive point is that ceramic remained vacuum leak free

27. Improvement of cylindrical window
SPL meeting, CERN
5-6 December 2012
Improvement of cylindrical window
Air inlet through
WG short circuit
A trick given by Michel Langlois (ex-Thales tube designer) is to improve air flow in the critical area in order to avoid ionization of the air around the ceramic itself
improve air cooling around ceramic with a short circuit as air inlet
Inserting PEEK screen all around ceramic
PEEK Screen all around ceramic

28. SW tests with coaxial disk windows
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
SW tests with coaxial disk windows
We then decided to start SW tests with coaxial disk windows
Up to date, we performed:
1000 kW 1.5 ms – 4 Hz
Some RF leaks were observed
CEA was finally not sure if these RF leaks were coming form couplers

29. SW tests with coaxial disk windows
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
SW tests with coaxial disk windows
Last week, while preparing test box with copper coated DT, we observed some arcing traces on the outer line in front of the inner contact
These traces were not present after TW test
There were no arc detector fault during the whole SW test (interlock active)
Arcing traces on inner line
Arcing traces on outer line

30. SW tests with coaxial disk windows
SPL meeting, CERN
5-6 December 2012
SW tests with coaxial disk windows
2009
2010
2011
2012
2013
Still waiting items to find an explanation
Possible candidates :
Not enough springs ensuring specific 1MW RF contact :
Inner ceramic is brazed with a stainless steel nut
Air cane is built with a specific bolt
Air cane is screwed compressing springs which when relaxed ensure 1 MW RF contact
Contact surfaces were not flat enough 2. 3. 1.

31. SW tests conclusion Cylindrical window couplers have performed
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
SW tests conclusion
Cylindrical window couplers have performed
575 kW 500 µs - 8 Hz full reflection all phases -> very strong arcing, interlock not operative
Coaxial disk window couplers have performed
1000 kW 1.5 ms - 4 Hz full reflection all phases, no interlock (operative), but few arcing traces (to be understood and explained)
SW tests are not conclusive, work still have to be done

32. Coated DT 6 DT with new copper sputtering have been processed :
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
Coated DT
6 DT with new copper sputtering have been processed :
Test with 150 Bars water have been performed
TD qualified
2 have been provided to cryomodule team
Unfortunately DESY clean room was not anymore available
CEA proposed to assemble couplers and copper sputtered DT onto test boxes in ‘L’orme les Meurisiers’ premises :
One Test box with two copper plated DT and two coaxial disk window has been assembled last week

33. Next steps Second test box will be assembled beginning 2013
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
Next steps
Second test box will be assembled beginning 2013
Cylindrical or Disk windows ? Decision after cylindrical arcing analysis
Beginning 2013, final tests at CEA with :
1000 kW TW 2 ms – 50 Hz
1000 kW SW limited to 200 µs – 50 Hz

34. Next steps EB welding of cryostat flanges will be done afterward
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
Next steps
EB welding of cryostat flanges will be done afterward
Study of clean room tooling for assembly onto SPL cavity has started
Assembly of couplers onto cavities in CERN clean room goal remains mid-2013
RF power tests on cavity asap

35. Next steps Provide a CERN clean assembly premises for couplers
SPL meeting, CERN
5-6 December 2012
2009
2010
2011
2012
2013
Next steps
Provide a CERN clean assembly premises for couplers
Continue all remaining couplers power tests with CERN amplifiers when available
Longer term basis :
After qualification of SPL cavities, make a test with ‘dirty’ couplers (ISO 7 instead of ISO 4 for example, tbd), to quantify coupler cleanliness impact onto cavity field

36. Key R&D results Mono bloc waveguides
SPL meeting, CERN
5-6 December 2012
Key R&D results Mono bloc waveguides 1. 2.
‘Plug and Play’ waveguide with matching step and DC capacitor included :
Connect the waveguide to the body line
Insert the contacts ring
Final assembly of air cooling system
No doorknob, reduced height, with no mechanical stress to the ceramic 3.

37. Key R&D results Test box
SPL meeting, CERN
5-6 December 2012
Key R&D results Test box
All in one, only two covers conditioning test box
Pros :
Easier (not easy) copper sputtering
Self supporting shape
Easily cleanable for SRF needs, can be used for several sets of coupler (if large series : SPL, ESS, …)
Cons :
Helicoflex faces to be very well prepared
Self-supporting structure : heavy weight

38. Key R&D results 3D printing & RF
SPL meeting, CERN
5-6 December 2012
Key R&D results 3D printing & RF
Successfully made available 3D printing for RF tests with a special silver paint
Machined
3D printed
@ 400 MHz
S21 = 0.01 dB
S11 = -40 dB
S21 = 0.03 dB
S11 = -25 dB
Delay [days]
Cost [CHF]
Machined 3D 15 5
9000
3800

39. Key R&D results High average power air cooled couplers
SPL meeting, CERN
5-6 December 2012
Key R&D results High average power air cooled couplers
Cylindrical window :
TW : 1000 kW 2 ms - 20 Hz
SW : 550 kW 500 µs - 8 Hz
Coaxial disk window :
TW : 1000 kW 2 ms - 20 Hz
SW : 1000 kW 1.5 ms - 4 Hz

40. Acknowledgements SPL coupler review committee : DESY : CEA : ESRF :
SPL meeting, CERN
5-6 December 2012
Acknowledgements
SPL coupler review committee :
Ali Nassiri, Wolf Dietrich Moeller, Mark Champion, Sergey Kazakov, Mircea Stirbet, Amos Dexter, Rama Calaga, Miguel Jimenez, Sergio Calatroni, Ofelia Capatina, Vittorio Parma
DESY :
Wolf-dietrich Moeller, Axel Matthaisen, Birte Van der Horst, and local team
CEA :
Stephane Chel, Guillaume Devanz, Michel Desmond, and local team
ESRF :
Jorn Jacob, Vincent Serriere, Loys, Jean- Maurice Mercier, Didier Boillot
APS :
Ali Nassiri, Doug Horan, Gian Trenko, Dave Brubenker, and local team
CERN :
Mechanical & Material Engineering group :
Francesco Bertinelli, Ramon Folch, Serge Mathot, Agostino Vacca, Thierry Tardy, Thierry Calamand, Thierry Renaglia, Ofelia Capatina, Marc Polini, Laurent Deparis, Philippe Frichot, Jean-Marie Geisser, Jean-Marc Malzacker, Pierre Moyret, Alain Stadler
Vacuum, Surface & Coating group :
Miguel Jimenez, Sergio Calatroni, Wilhelmus Vollenberg, Marina Malabaila, Nicolas Zelko
Magnets, Superconductors & Cryostats :
Vittorio Parma, Arnaud Van de Craene,
RF group :
Sebastien Calvo, Antoine Boucherie, all FSU-BE03 members

41. Thank you very much for your attention
SPL meeting, CERN
5-6 December 2012
Thank you very much for your attention