1. VERTICAL TEST RESULTS OF SPOKE RESONATOR AT IPNO

2. OUTLINE ESS Spoke Resonator ESS Project MYRRHA Project
Double Spoke resonator presentation
Cavity preparation and test configuration
Results of tests
2 prototypes from Zanon
1 prototype from SDMS
MYRRHA Project
Simple Spoke resonator presentation
Vertical test configuration

3. RAPPEL TITRE PRESENTATION
mardi 31 juillet 2018
4 HPR Ports
Pick-up Port
ESS Spoke Resonator
E field
Lorentz detuning :
Simulated : -5.5 Hz/(MV/m)2
Measured : -6.8 Hz/(MV/m)2
Pressure sensitivity :
Measured : 24.3 Hz/mbar
DOUBLE-SPOKE CAVITY
Frequency [MHz]
352.21
Beta_optimum
0.50
Operating gradient [MV/m]
9.0
Temperature (K) 2
Bpk [mT] 62
Epk [MV/m] 39
G [Ohm]
130
r/Q [Ohm]
426
Lacc
(=beta optimal x nb of gaps x λ /2) [m]
0.639
Bpk/Eacc [mT/MV/m]
6.88
Epk/Eacc
4.34
P max [kW]
335
Coupler port
Stiffeners
H field

4. Test configuration ESS Spoke Resonator Cavity preparation
Ultra-sonic degreasing
Etching of 200 µm (goal)
Phase 1: Horizontal, 120 minutes
Phase 2: Horizontal (180° rotation), 120 minutes
Phase 3: Vertical, 240 minutes
2 barrels to limit acid temperature < 18°C
Cold water in helium tank
HPR : 12h
6 ports (2 beam tubes, 4 HPR ports)
24h drying
Vertical test done « in vertical ».
Cooling is not optimal : gas pocket
ESS Spoke Resonator

5. Tests results : ROMEA
ESS Spoke Resonator
6h at 100K
Bad Baking ??

6. Tests results : ROMEA
ESS Spoke Resonator
Bad Baking ??

7. Tests results : ROMEA
ESS Spoke Resonator
30 microns BCP

8. Tests results : ROMEA ESS Spoke Resonator Room temperature cycle
+cavity opened + HPR

9. Tests results : Giulietta
ESS Spoke Resonator
Bad Baking again ??

10. Tests results : Giulietta
ESS Spoke Resonator
Additional etching
Baking 3
Fast Room temperature cycle 1 4 2

11. Conclusions ESS Spoke Resonator
Q-disease not dissolved at room temperature ?
Possible if hydrogen concentration high enough ?
Or surface is damaged by precipitation ?
Presence of skeletons
But nothing observed with confocal microscope on Niobium samples placed on a cavity during a test
See : Advances in SRF Material Science aimed at High Q cavities. A. Grasselino
SRF Development Department, TD Fermilab
NA-PAC 2013
Pasadena, California

13. Conclusions ESS Spoke Resonator Why never observed on
Spiral2 QWR ?
Same facilities (BCP, HPR)
Same Niobium (Tokyo Denkai)
Hydrogen degassing
is compulsory for ESS cavities
New furnace at IPNO

14. RAPPEL TITRE PRESENTATION
mardi 31 juillet 2018
MYRRHA Spoke Resonator
E field
Lorentz detuning :
Simulated : -5.5Hz/(MV/m)2
Measured : -8.2 Hz/(MV/m)2
Pressure sensitivity :
Simulated : 11 Hz/mbar
Measured : 236 Hz/mbar
H field

15. MYRRHA Spoke Resonator
Test configuration
MYRRHA Spoke Resonator
Cavity preparation
Ultra-sonic degreasing
Etching of 200 µm (goal) (~ 0.4 µm/min)
Phase 1: Horizontal, 200 minutes
Phase 2: Horizontal (180° rotation), 100 minutes
Phase 3: Same position but fresh acid, 100 minutes
2 barrels to limit acid temperature < 18°C
Cold water in helium tank
HPR :
4 ports (2 beam tubes, 2 coupler ports)
48h drying
Vertical test done « in horizontal ».
Amélia : tested with helium tank
Virginia : cavity fully immersed in helium
(dunk test)

16. MYRRHA Spoke Resonator
Tests results : Amélia
MYRRHA Spoke Resonator
Test with helium tank
Quench
BCP : ~ 300 µm

17. Tests results : Virginia
MYRRHA Spoke Resonator
Dunk test
BCP : ~ 150 µm

18. MYRRHA Spoke Resonator
Conclusions
MYRRHA Spoke Resonator
Q-disease test not performed yet on MYRRHA cavities
Strong Q-slope on both cavities
Probably hydrogen contamination
Hydrogen degassing
will be tested this year
650°C with Ti tank