1. RF test results of SRF cavity evacuated with NEG pump
G. Ciovati
07/28/16

2. Schematic CapaciTorr HV200 with 2 ¾” CF on loan from SAES Getters
11/27/2018

3. Pump cleaning
Blow-off with ionized N2 in ISO 5 clean room at ~6” from particle counter
Sampled volume: 0.17 ft3

4. Preparation for 1st RF test
Cavity HPR
Evacuation with turbo-pump
Valves V1 and V2 closed

5. Test results

6. Next steps
A burst disk was broken because valve V2 had a leak in “closed” position
The vacuum manifold was disassembled and re-cleaned, the cavity re-HPR
RF test repeated, similar results as test 1
After RF test:
the vacuum manifold was connected to turbo-pump
NEG pump was activated for 1 h, then isolated from turbo-pump and opened to the cavity. The cavity was pumped by NEG for 3 days*
3rd RF test
*Cold-cathode gage had a leak and did not measure pressures below 1.5e-6 mbar

7. Test results
Test 2
Test 3

8. Next steps After RF test: 4th RF test
the vacuum manifold was connected to turbo-pump with new cold-cathode gage
Valves V1 and V2 opened. RGA spectrum measured
Cavity isolated from turbo-pump and on NEG pump for ~ 5 h
It was realized that the actuator of valve V2 was broken and the valve was only slightly open.
V1 was closed, then the vacuum manifold was vented and V2 replaced. Re-evacuated with turbo-pump, then closed V2
4th RF test

9. RGA spectrum

10. Test results

11. Next steps After RF test: RF test
Vacuum manifold connected to turbo-pump on test stand
Opened V2, NEG pump activated for 2 h, pressure plateaued to 1.3e-6 mbar, then switched to normal heating mode
Opened V1, then isolate from turbo-pump
Cavity pumped by NEG pump for ~7 days. Pressure monitored.
Closed V1 and V2
RF test

12. Pressure during pumping with NEG
Cavity isolated from turbo-pump
Cavity isolated from NEG pump for cold test
Gage “underrange” (<5e-9 mbar)

13. Test results

14. Conclusion
NEG pump is compatible with SRF cavity operation up to high gradient (Epeak~63 MV/m)
The pump is very easy to use and is very robust (5 thermal cycles from 300 K to 2 K)

15. Acknowledgments
Y. Lushtak and P. Manini from SAES Getters for lending the CapaciTorr pump
Rongli Geng for helping with cavity test
Cavity Production group for help with cavity preparation and assembly
Arne Freyberger and Bob Rimmer for supporting this work