1. Double-Spoke Cavities
Tracking of the frequency during the
ZANON & the preparation of the first 4 IPNO
Guillaume OLRY
on behalf of the ESS IPNO team

2. Outline Fabrication @ ZANON Tuning & Welding of the naked cavity
Integration of the helium vessel
IPNO
Chemical etching
Heat treatment

3. Fabrication [1] 29 cavities currently under fabrication at ZANON
One important parameter is monitored all along the fabrication process: the frequency of course !
Main fabrication phases:
Tuning: freq meas trimming #1 of the cavity body  freq meas  final trimming operation  freq meas
Cavity body: extra length of ~10 mm (5mm on each end)

4. Fabrication [2]
End-cups welding (EB welding): freq shift due to the weld shrinkage (mostly!)
Leak tightness test of the welded naked cavity: freq shift due to mechanical stress release
Cavity #
Freq shift (kHz)
Shrinkage (mm)
With freq*
With length**
DSPK05
-120
-1.11
-1.68
DSPK06
-71
-0.67
-1.65
DSPK03
-135
-1.27
-2.02
DSPK04
-81
-0.76
-1.45
*Taking into account a calculated sensitivity of 106 kHz/mm
**Flange-to-flange cavity length
Cavity #
Freq shift (kHz)
DSPK05
-48
DSPK06
-44
DSPK03
-35
DSPK04
-37

5. Fabrication [3]
Helium tank integration (TIG welding): 14 freq measurements all along the process

6. Fabrication [6] Two different ways of integration:
1/ “ZANON touch” for DSPK05 & 06 : pulling action (=plastic deformation) on the beam tubes of about 1 mm. Goal: compensate the shrinkage of the helium vessel during the welding process.
2/ “IPN style” for DSPK03 & 04: no pulling
Cavity #
Pulling action
Total freq shift (kHz)
Welder
DSPK05
YES  +140 kHz
-33 A
DSPK06
YES  +147 kHz
-171 B
DSPK03 NO
-35
DSPK04
-190 C
Critical welding operations have been identified.
ZANON has proposed a new design of the chamfers on the helium tank parts (more flexibility) and IPNO agreed to reduce the number of passes during the TIG welding (less heat  less deformation).

7. Fabrication [7]
Last step: machining of the blocks used for the tuning system & the survey targets on each end-cup.
BONUS!!! « Repair » on DSPK05 & 06: misalignment of the beam tubes
~1mm on one beam tube of DSPK05 (bellows side only)
>1mm on both beam tubes for DSPK06
 +44 kHz on DSPK06 freq. No meas on DSPK05.
Misalignment not observed on DSPK03 & 04.
Could have been caused by the pulling action…
Cavity #
Freq shift (kHz)
DSPK05
-40
DSPK06
-31
DSPK03
-48
DSPK04
-51

8. Summary: freq shift from end-cup welding to « ready for shipment »
Fabrication [7]
Leak tighness test: before shipment
Summary: freq shift from end-cup welding to « ready for shipment  »
Cavity #
Freq shift (kHz)
DSPK05
-31
DSPK06
-17
DSPK03
-33
DSPK04
-23
Cavity #
Freq shift (kHz)
DSPK05
-270
DSPK06
-326
DSPK03
-452
DSPK04
-230

9. Preparation of a cavity
BLUE: Reception
GREEN: Chemical etching
ORANGE: Clean room
RED: Heat treatment

10. Chemical etching before heat treatment Impact on the frequency ?
Critical phases
Chemical etching before heat treatment
Heat Treatment HT
Impact on the frequency ?
Etching
ACTIONS:
« Calibration » process for the chemical etching
Nothing for the heat treatment

11. Preparation: dimensional controls

12. Preparation: chemical etching
The cavity can be set in Horizontal or Vertical position.
H: Frequency decreases
V: Frequency increases
The “Calibration” process started with DSPK05 & 06 to get the sensitivities: kHz/µm, kHz/min & µm/min

13. Preparation: chemical etching
Summary
Mean values for heavy chemistry:
H: kHz/µm & 0.40 µm/min
V: kHz/µm & 0.30 µm/min

14. Preparation: heat treatment
Cycle with 3 plateaux:
300°C for 90min (checking of the organic compounds: grease…)
500°C for 1h (care of the bi-metallic joint)
650°C for 10h (H degassing) 1 2 3 3
1.6°C/min 2
2.2°C/min 1
3°C/min

15. Preparation: heat treatment
Results
Cavity #
Freq shift (kHz)
DSPK05
-30
DSPK06
+39 (!!!!)
DSPK03
-14
DSPK04
-22
Pulling action during the integration of the tank + repair operation on both beam tubes
Beam tube deformed on
DSPK05
DPSK06
Beam tube deformed on
DPSK06

16. Expected frequency shift (kHz)
Summary
Operations
Expected frequency shift (kHz)
ZANON
After EB welding of the end-cups
-100
After the leak check (naked cavity)
-40
After the tank integration
-50
After the final machining
Before shipment (incl final leak check)
-25
IPNO
Chemical etching
-110 to +60
Heat treatment
-265 kHz
Chem. Etching can be neutral

17. Vertical test DSPK05 is presently being tested in vertical cryostat
Measurements in Sept 2018 (only cooldown, no RF).
∆f (300K --> 4K): MHz (calculated: MHz)
∆f (4K --> 2K): MHz (calculated: MHz)
∆f (300K --> 2K): MHz
2 hours ago… Qo vs. Eacc (at 4K)
Qo=
No field emission
6 MV/m

18. Prototype valve box & cryomodule activities @ UU
Slides from
P. DUTHIL (CNRS-IN2P3 IPN Orsay / Division Accélérateurs)
on behalf of the IPNO team

19. Prototype cryomodule and valve box
Installation at FREIA (Uppsala Univ)
Beginning of October (W40)
Unpacking of all components
Positioning of the VB into the bunker
Connection of the wave guides
Positioning
Test VB positioned
Wave guides assembly

20. Prototype cryomodule and valve box
Installation at FREIA (Uppsala Univ)
Beginning of October (W40)
Installation of some equipment (vacuum pump, control valves that were disassembled for transportation, etc)
Post-shipment leak test of all cryogenic circuits and vacuum vessel
Vacuum pump installed
Leak tests of all circuits

21. Prototype cryomodule and valve box
Installation at FREIA (Uppsala Univ)
Beginning of October (W40)
Positioning of the test LHe tank on the VB for checking piping corrections
(the test LHe will be used at Uppsala for:
cryogenic operations of the VB in the FREAI infras)
testing the mounting of Cernox temperature sensor
Back to IPNO : finalization of this tank
 to be sent to Uppsala next week
Test LHe tank
Positioning the test LHe tank on the VB
All components of the test LHe tank now ready at IPNO

22. Prototype cryomodule and valve box
Installation at FREIA (Uppsala Univ)
Beginning of October (W40)
Assembly of the two doorknobs
Trust me Felix: I’m sure you fit in this box !
Avoiding clashes

23. Prototype cryomodule and valve box
Installation at FREIA (Uppsala Univ)
Beginning of October (W40)
Assembly of the two doorknobs
Positioning of the CM wrt the VB (cryogenics + waveguides)

24. Prototype cryomodule and valve box
Installation at FREIA (Uppsala Univ)
Beginning of October (W40)
Assembly of the PLC and instrumentation cabinets (2 cabinets):
voltage supply installation
connections of the cabinets together
setting the installed external cables into the cabinet and connecting them onto the terminal blocks
The 2 cabinets
Cable installation
Terminal blocks conections

25. Prototype cryomodule and valve box
Installation at FREIA (Uppsala Univ)
Beginning of October (W40)
FREIA-ESS-IPNO team

26. Thank you for your attention