Fabrication and measurement of RF components for CLIC study CERN summer school programme 2010 Fabrication and measurement of RF components for CLIC study Thapakron Pulampong Physics department, Khon-Kaen University, Thailand 18/8/2010

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 Machining->Chemical cleaning Cu layer12-15 µm Machining->Chemical cleaning-> Ni-plating -> Cu-plating

Brazing of RF flanges with a waveguide Under vacuum With brazing wire Ag/Cu/Pd at 810-820 °C (Bodycote) (Silver/Copper/Palladium) Structure after brazing

Vacuum leak test With A.Olyunin Clean bolts and nuts with alcohol and ultrasound 20 minutes Clean vacuum flanges with alcohol Vacuum leak detector Connect vacuum flanges with the structure

Object: RF flanges and straight waveguide CERN TE/VSC LEAK TEST CERTIFICATE Description of examination Customer: CERN BE/RF Object: RF flanges and straight waveguide Leak test date: 19.07.2010 Leak detector type: LEYBOLD L200⁺ . Reference leak rate: 6.2±15% ×10⁻⁷mbar×L/s Minimum detectable leak rate: 1×10⁻¹¹ mbar×L/s Tracer gas: Helium 99% System pressure: 1×10⁻³ mbar Test temperature: 20 ̊C Examined part Brazing Results Max. measured leak rate: 3.6×10-11 mbar×L/s Good results!

RF measurement With A.Olyunin RF flanges+waveguide RF test flanges Clean all surface to be connected with alcohol Connect RF test flanges with RF flanges +waveguide Connect network analyzer with the sample and start testing RF test flanges 2ports network analyzer Calibrated before test

RF measurement result Good results! Frequency (GHz) S-parameter (dB) 11.4240 -31.029 -31.273 11.9920 -29.395 -29.884 Good results!

Diffusion bonding test Bonding temperature : 1040 °C Time : 1h 30m Atmosphere : H2 Prototype disks for PSI accelerating structures 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 Stack no.1 Stack no.2 with 1 insert for test validation process of bonding or brazing.

Chemical cleaning procedure Degreasing with detergent NGL 17.4 spec. ALU III and ultrasound Deoxidation with HCl acid Etching with SLAC solution Final rinsing with demineralised water and ultrasound Dry with nitrogen gas Dry with oven With M.Balabaila

Vacuum before H2 injection for diffusion bonding Bodycote Root pump 10-3 torr Primary pump 10-1 torr Diffusion pump 10-6 torr

Diffusion bonding Heating system made of Molybdenum screens (melting point is 2617.0 °C): temperature of 1040 °C for the bonding process.

Cool down Cooling system is composed of water cooling and air cooling. Water spray Because of water spray and cooling turbine, the temperature can be reduced rapidly. Cooling turbine Air tank

Diffusion bonding no.1 weight of 16 Kg Vacuum  H2  Heat up to 1040 C CERAMICS 4 temperature probes (thermo-couples) in tuning holes Furnace warm up and clean up ceramics and support before bonding. Bonding process 1:30h

Diffusion bonding no.2 weight of 16 Kg CERAMICS 2 temperature probes (thermo-couples) Furnace warm up and clean up before bonding. Bonding process 1:30h

Stacks after Bonding Stack no.1 Stack no.2 with 1 insert

Metallographical observation M. Aicheler Metallographical observation Bonding no.1 SOI 6 SOI 5 SOI 1 SOI 2 SOI 7 SOI 4 Stack no.1 after cutting Contact reference line

Metallographical observation M. Aicheler Metallographical observation Bonding no.2 5 4 3 2 1 SOI 6 SOI 7 SOI 5 SOI 1 SOI 2 SOI 3 Stack no.2 after cutting Installed insert before bonding process after cutting

Stack no.2 metallographic observation Joint no. 4 Joint no. 5 Grain crossing Grain crossing Contact reference line Designed contact zone Designed contact zone M. Aicheler

Conclusion RF flanges + straight waveguides Bonding tests Vacuum leak 3.6× 10-11 mbar·l/s (< 10-10 )( Good) RF reflection about -30 dB (Good) 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.