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5 cell 704 MHz SRF Cavity. R&D ERL 5 cell 704 MHz SRF Cavity. Andrew Burrill. February 17-18, 2010. The Cavity. 5 cell SRF cavity, 17 cm iris, 24 cm beampipe 703.75 MHz, 20 MV/m @ Q o =1e 10 No trapped HOMs Cavity is inherently stiff, so no additional stiffeners are needed - PowerPoint PPT Presentation
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February 17-18, 2010
R&D ERL
Andrew Burrill
R&D ERL5 cell 704 MHz SRF Cavity
Andrew Burrill
February 17-18, 2010
5 cell 704 MHz SRF Cavity
February 17-18, 2010
R&D ERL
Andrew Burrill
The Cavity
• 5 cell SRF cavity, 17 cm iris, 24 cm beampipe
• 703.75 MHz, 20 MV/m @ Qo=1e10
• No trapped HOMs• Cavity is inherently stiff, so no additional
stiffeners are needed• Coaxial FPC for power delivery• Ferrite Dampers for HOMs• 5 K heat intercept on beampipe• Mechanical Tuner with 100 kHz tuning
range, piezo provides 9 kHz fast tuning
2
February 17-18, 2010
R&D ERL
Andrew Burrill
Cryomodule Configuration
2K main line
Inner magnetic shield
Cavity assembly
4” RF shieldedgate valve (2)
2K fill line
He vessel
Vacuum vessel
Fundamental PowerCoupler assembly
HOM ferriteassembly
Outer magnetic shield
Thermal shield
Cavity Tuner location
Space framesupport structure
Heater
Cold-to-Warm BeamPipe Transition (2)
HOM ferriteassembly
February 17-18, 2010
R&D ERL
Andrew Burrill
1st and 2nd mode 96.8 Hz
3rd mode 203.5 Hz
4th and 5th mode 213.6 Hz
Mechanical and Electromagnetic Analysis• Finite element models were used to evaluate the thermal, structural, and RF
behavior thermal load, pressure load, and loads from the cavity tuner• Cavity is inherently stiff due to large angle cell faces no iris stiffeners, 3mm
niobium thickness
Tuner Load and Frequency Shift
0
1000
2000
3000
4000
5000
6000
7000
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18Cavity Displacement (in)
Tune
r Loa
d (lb
s)
-450
-400
-350
-300
-250
-200
-150
-100
-50
0
Freq
uenc
y Sh
ift k
HzLoad
Freq. shift
MECHANICAL MODES ANALYSIS
ELECTROMAGNETIC ANALYSISLORENTZ FORCE DETUNING
February 17-18, 2010
R&D ERL
Andrew Burrill5
String Assembly & Installation
February 17-18, 2010
R&D ERL
Andrew Burrill6
Cryomodule Testing and Lessons Learned
• To date the cryomodule has been tested 4 times.• There are signs of field emission, which prompted us to try Helium
processing• Currently limited by our cryogenic capacity
– This should be resolved in the next year• All systems operational• HOM measurements have been carried out at 4K and 2K and match
well with simulations• LLRF system and 50 kW transmitter working well, both c.w. and
pulsed.• Field in the beampipe manifests itself as a low Qo. This is a function of
the large beampipe, and the power dissipated in the 5K circuit should not affect the cavity performance.– This was modeled in superfish (AES) in 2004.
February 17-18, 2010
R&D ERL
Andrew Burrill7
Summary
• Cryomodule Testing is ongoing with improvements made each time the cavity is tested.
• A better understanding of the heating in elements cooled by the 5 K circuit is being developed and a plan to increase the cooling capacity in this circuit being devised.
• Testing length and integrated operational time at gradient will be greatly improved once the refrigerator is online.
• Field emission remains a problem that we have not had sufficient time at gradient to properly process.
![Mechanical Design of the 704 MHz 5-cell SRF Cavity Cold ...accelconf.web.cern.ch/accelconf/IPAC2014/papers/wepri081.pdf · The piping analysis was done using CAEPIPE [6]. Proceedings](https://img.dokumen.tips/doc/110x75/5a73627e7f8b9abb538e90e7/mechanical-design-of-the-704-mhz-5-cell-srf-cavity-cold-a-the-piping-analysis.jpg)
