fabrication and measurement of rf components for clic study thapakron pulampong physics department,...
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Fabrication and measurement of RF components for CLIC study
Thapakron Pulampong Physics department, Khon-Kaen University, Thailand
18/8/2010
CERN summer school programme 2010
• RF flanges + straight waveguides Objective: To study how Cu-plating (12-15 µm) of RF flanges affects
vacuum and RF properties after brazing with straight waveguides.
- brazing- vacuum leak test- RF measurement
• Diffusion bonding study (PSI prototype disks) Objective: To study diffusion bonding quality using metallographic observation.
- chemical cleaning for disks- diffusion bonding process- metallographic observation
RF flanges + Straight waveguides
Cu layer12-15 µm
Machining->Chemical cleaning-> Ni-plating -> Cu-plating
Machining->Chemical cleaning
Brazing of RF flanges with a waveguide
• With brazing wire Ag/Cu/Pd at 810-820 °C (Bodycote)
(Silver/Copper/Palladium)
Under vacuum
Structure after brazing
Vacuum leak testClean bolts and nuts with alcohol and ultrasound 20 minutes
Clean vacuum flanges with alcohol
Connect vacuum flanges with the structure
Vacuum leak detector
With A.Olyunin
Customer:CERN BE/RF Object: RF flanges and straight waveguide
Leak testdate:
19.07.2010
Leak detector type: LEYBOLD L200⁺ .Reference leak rate: 6.2±15% ×10⁻⁷mbar×L/sMinimum detectable leak rate: 1×10⁻¹¹ mbar×L/sTracer gas: Helium 99%System pressure: 1×10⁻³ mbarTest temperature: 20 C ̊�
Brazing
Max. measured leak rate: 3.6×10-11 mbar×L/s
CERN TE/VSC LEAK TEST CERTIFICATEDescription of examination
Examined part
Results
Good results!
RF measurement
Connect RF test flanges with RF flanges +waveguide RF test flanges
Clean all surface to be connected with alcohol
RF flanges+waveguide
Connect network analyzer with the sample and start testing
2ports network analyzerCalibrated before test
With A.Olyunin
RF measurement result
Frequency(GHz)
S-parameter (dB)S11 S22
11.4240 -31.029 -31.27311.9920 -29.395 -29.884
Good results!
Diffusion bonding test
Stack no.2 with 1 insert for test validation process of bonding or brazing.
Regular cell disk: 2-46
Wake monitor cell disk:8-43
Wake monitor dell disk:5-40
Wake monitor cell disk:4-37
Wake monitor cell disk:3-36
Regular cell disk: 2-35
INSERT1 INSERT2
Standard cell disk 2-55
Standard cell disk 2-55
Standard cell disk 2-55
Standard cell disk 2-55
Standard cell disk 2-55
Bonding temperature : 1040 °C Time : 1h 30m Atmosphere : H2
Stack no.1
Prototype disks for PSI accelerating structures
Chemical cleaning procedure
Degreasing with detergent NGL 17.4
spec. ALU III and ultrasound
Deoxidation with HCl acid
Etching with SLAC solution
Dry with nitrogen gas
Dry with oven
Final rinsing with demineralised water
and ultrasound With M.Balabaila
Vacuum before H2 injection for diffusion bonding
Primary pump 10-1 torr
Root pump 10-3 torr
Diffusion pump 10-6 torr
Bodycote
Diffusion bondingHeating system made of Molybdenum screens (melting point is 2617.0 °C): temperature of 1040 °C for the bonding process.
Cool downCooling system is composed of water cooling and air cooling.
Water spray
Cooling turbine
Air tank
Because of water spray and cooling turbine, the temperature can be reduced rapidly.
Diffusion bonding no.1
4 temperature probes (thermo-couples) in tuning holes
CERAMICS
Vacuum H2 Heat up to 1040 C weight of 16 Kg
Furnace warm up and clean up ceramics and support before bonding.
Bonding process 1:30h
Diffusion bonding no.2
CERAMICS
weight of 16 Kg
Furnace warm up and clean up before bonding.
Bonding process 1:30h2 temperature probes (thermo-couples)
Stacks after BondingStack no.1
Stack no.2 with 1 insert
SOI 1
SOI 2
SOI 4
SOI 5SOI 6
SOI 7
Metallographical observation Bonding no.1
Contact reference line
Stack no.1 after cutting
M. Aicheler
SOI 1
SOI 2
SOI 3
SOI 5SOI 6
SOI 7
12345
Metallographical observation Bonding no.2
Installed insert before bonding process after cutting
Stack no.2 after cutting
M. Aicheler
Stack no.2 metallographic observation
Grain crossingGrain crossing
Designed contact zone Designed contact zone
Joint no. 4 Joint no. 5
Contact reference line
M. Aicheler
Conclusion
• Vacuum leak 3.6× 10-11 mbar·l/s (< 10-10 )( Good)• RF reflection about -30 dB (Good)
RF flanges + straight waveguides
Bonding tests• Successful: grain crossing can be found in areas with and without designed contact.• Inserts should not be diffusion bonded, but brazed, as originally foreseen.