1 / 31

SPL power coupler

SPL power coupler. Possible proposed designs Part II : designs comparison. Summary. Comparison of proposed designs: SPL-CEA coaxial disk water cooled window SPL-SPS coaxial disk air cooled window SPL-LHC cylindrical air cooled window Design issues Waveguides Titanium coating

brooklyn
Download Presentation

SPL power coupler

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. SPL power coupler Possible proposed designs Part II : designs comparison Eric Montesinos / CERN-BE-RF-SR

  2. Summary • Comparison of proposed designs: • SPL-CEA coaxial disk water cooled window • SPL-SPS coaxial disk air cooled window • SPL-LHC cylindrical air cooled window • Design issues • Waveguides • Titanium coating • RF simulations • Coupling box • Construction process • Conditioning process • Mass production • New proposed schedule • Conclusion Eric Montesinos / CERN-BE-RF-SR

  3. Three possible remaining designs • All use the same double walled tube • All use the same vacuum gauge, electron monitor and arc detector • We have designed them to be compatible without modifying the cryomodule Eric Montesinos / CERN-BE-RF-SR

  4. Three possible remaining designs • SPL-CEA HIPPI coaxial disk water cooled window • SPL-SPS coaxial disk air cooled window • SPL-LHC cylindrical air cooled window Eric Montesinos / CERN-BE-RF-SR

  5. Coaxial disk water cooled window • CEA design based on a coaxial disk ceramic window as in operation at KEKB and SNS, modified for 704MHz • Advantages • High power capability, tested up to 1MW with 2ms / 50Hz on warm test cavity and on cold cavity last week • Matched window, this allows to easily change the waveguide position • Commercially produced window (Toshiba) • Drawbacks • Window and antenna are water cooled: • Not following CERN vacuum group recommendations • Needs accurate mounting • Difficult DC HV biasing due to water: • Need insulating pipes (X-rays, radiation,... More maintenance and operational costs) • Need a second air cooling circuit for the waveguide: • Doubles the operational needs: water and air systems Waveguide air cooling Antenna and outer ceramic water cooling Eric Montesinos / CERN-BE-RF-SR

  6. Coaxial disk water cooled window • Quite complex brazing process (compare to SPS and LHC) • Water seal to be modified from organic (acceptable for test) to metallic (for long term operation without maintenance) • the tolerances are very tight • No flexibility for the antenna: • Stress to the ceramic • RF contact depends on tolerances • Possible water leak if misalignment (already happened) Eric Montesinos / CERN-BE-RF-SR

  7. Coaxial disk air cooled window • Design based on a coaxial disk ceramic window similar as the one in operation on the CERN SPS TWC 200MHz power load • Advantages • Very simple and well mastered brazing of ceramic onto a titanium flange • High power capability (500kw cw) • Very easy to cool with air • Waveguide as “plug and play” mounting, absolutely no stress to the antenna • DC HV biasing very simple, with again a “plug and play” capacitor fitting, and again no stress to the ceramic due to finger contact • Least expensive of the three couplers ! • Minor drawback • Ceramic is part of the matching system, fixes the waveguide position Ceramic and waveguide air cooling Antenna and outer ceramic air cooling Eric Montesinos / CERN-BE-RF-SR

  8. Coaxial disk air cooled window • Very simple brazing process: • Titanium outer flange: • Dilatation coefficient near ceramic • Surface hard enough for vacuum copper seals • Inner tube in copper 1.2mm thickness to allow easy brazing • Antenna inner upper part has been designed: • With spring washers for a good RF contact between the upper and lower inner conductor sections • Without any stress to the ceramic • Allowing a correct air flow SPS Window: very simple brazing process Spring washers Air “cane” RF contact RF contact without stress to the ceramic by compression of the outer line through the air “cane” Eric Montesinos / CERN-BE-RF-SR

  9. “Plug and play” waveguide system • Need additional 50 Ωouter lines: • Vacuum side for monitoring vacuum, electron, light, … • Air side for RF matching and for air cooling of the ceramic • “Plug and play” waveguide and biasing capacitor • There is a finger contact all around the capacitor to avoid stress on the ceramic • This waveguide mounting method has already been used successfully for the LHC couplers Eric Montesinos / CERN-BE-RF-SR

  10. Cylindrical air cooled window • Design based on the same cylindrical window as the LHC couplers: • Long and difficult process to achieve reliability of the window, the final design was obtained after more than six years of studies • As the design was complex, we keep it exactly as it is • Instead of changing the ceramic design we have adapted the line to the ceramic • Advantages • High power capability window, LHC proven (575kW cw full reflection, could be more…) • Simple to cool with air • Absolutely free of mechanical stress on the antenna • Same “plug and play” waveguide and DC capacitor as previous design, no stress to the ceramic • Simplest version to assemble ! • Drawbacks • Ceramic is part of the matching system, fixes the waveguide position • Possible multipacting due to the outer conical outer line Ceramic and waveguide air cooling Eric Montesinos / CERN-BE-RF-SR

  11. Cylindrical air cooled window • LHC window is a huge improvement over the LEP window, with less losses and higher power capability • We still not know the upper power limit of the LHC window • The LHC coupler were powered up to 575kW cw full reflection (SW) for several hours all phases • Klystrons failed, not the coupler ! • The LHC window appears to be really robust • To date 30 LHC couplers have been built and tested, 16 are in operation in LHC • A new coupler using exactly the same ceramic window is under construction for ESRF and SOLEIL → Standardization of the ceramic ESRF-LHC new design LHC window: Two solid copper collars brazed to the ceramic First EB welding (mechanical) Third EB welding (mechanical and vacuum) Second EB welding (mechanical and vacuum) Eric Montesinos / CERN-BE-RF-SR

  12. “Plug and play” waveguide system • Same “Plug and play” waveguide and biasing capacitor as with the coaxial air cooled window • The waveguide has just one contact with the body line • There is a finger contact all around the capacitor to avoid stress on the ceramic Eric Montesinos / CERN-BE-RF-SR

  13. Comparison: Titanium coating • LHC, coating done twice: • First coating on the top and the bottom edges of the ceramic (electrical continuity) • Brazing of the copper collars • Second coating on the inside of the ceramic • → Double the costs • SPS, only one coating: • Straight forward • Done after brazing • Toshiba process: • Probably one coating • What about the part of ceramic masked by the chokes? First coating: R = 0.5 MΩ Second coating: R = 2 MΩ One coating: R = 2 MΩ ? What about the part of ceramic behind the choke ? One coating: R = 2 MΩ Eric Montesinos / CERN-BE-RF-SR

  14. Comparison: S11 simulations Cavity bandwidth 704 MHz / Qext (1.2 x 106) = 586 Hz SPL-CEA SPL-LHC SPL-SPS Eric Montesinos / CERN-BE-RF-SR

  15. Comparison: Field Strength SPL-CEA Max 751 kV/m with 1MW SPL-SPS SPL-LHC Max 880 kV/m with 1MW Max 866 kV/m with 1MW Eric Montesinos / CERN-BE-RF-SR

  16. Waveguides options • If needed, LHC design could be done with a “coaxial conical” extension line to change the waveguide position • We simulated the waveguide with steps to check effects on the field distribution, it reduces the field strength • Using a waveguide without doorknob considerably eases the mounting and reduces the cost (as LHC) • Immediately after the coupler waveguide flange, there will be a flexible waveguide to reduce mechanical stresses • Nevertheless, a supporting tool will be necessary for the coupler waveguide, still to be studied LHC design with a possible conical coaxial extension to change the waveguide axis Two steps waveguide: slightly reduces the field strength Doorknob / reduced height: ~ same field strength Eric Montesinos / CERN-BE-RF-SR

  17. Comparison Eric Montesinos / CERN-BE-RF-SR

  18. Coupling box • Will be used to: • Connect two couplers in the vertical position for conditioning • Storage and transport chamber with springs to damp shocks • Solid copper: • Low RF losses • Strong enough to sustain deformation due to strong pressure effects • Extra external mechanical adjustment for frequency tuning • Could be EB soldered or assembled from two parts: • Vacuum seal • Easy to clean, we want to re-use it for 250 couplers ! Springs to avoid any shock while transporting Eric Montesinos / CERN-BE-RF-SR

  19. Vacuum leak detections after each major operation Construction process • We plan to follow an upgraded LHC coupler construction process: • Build all components: • Metrologic controls • Mechanical and thermal tests • In clean room (class 100): • clean all parts in contact with beam vacuum with pure water or pure alcohol • Particle counting to validate the cleaning • In clean room (class10): • assemble a pair of couplers and mount them on a test cavity • Bake out • RF conditioning • In clean room (class 10): mounting of coupler with its double walled tube on SPL cavity Eric Montesinos / CERN-BE-RF-SR

  20. Construction process • To be carefully followed-up: • Assembly tooling • Handling with special gloves only, avoid contamination of surfaces by hydrocarbons, finger prints,… • Optimize the process to minimize the number of handlings • Avoid intermediate packing in polymeric sealed bags (contamination) • Specially designed transport containers • Visit tomorrow of the three facilities: • Building 252 class 100 clean room • Building 252 class 10 clean room • Building SM18 class 10 clean room • Would like advice on what we could improve for high gradient cavities Eric Montesinos / CERN-BE-RF-SR

  21. Conditioning process • Install one cavity with its two power couplers and prepare for conditioning • List of interlocks and monitoring: • Vacuum gauges • Directional couplers • Light detector • Electron monitor • Thermal measurements • Gas analyzer • Air flow meter • Water flow meter (power load) • … • The tests will be done at CEA Saclay TTF III power coupler test bench Eric Montesinos / CERN-BE-RF-SR

  22. Conditioning process • The conditioning loop will be the same as the one used since 1998 with the SPS and LHC couplers: • A first direct vacuum loop (red) ensures RF is never applied if pressure exceeds 5.0 x 10-7 mbar • A second vacuum loop (blue), cpu controlled, executes the automated process • The interlock vacuum threshold of 5.0 x 10-7 mbar will be chosen, guided by our experience, to protect the couplers, but also to have an as short as possible conditioning time • The settings are adjusted to have minimum attenuation under 1.0 x 10-8 mbar and maximum attenuation over 2.5 x 10-7 mbar (~40 dB dynamic range with the attenuator) Eric Montesinos / CERN-BE-RF-SR

  23. Conditioning process • The conditioning process will be similar to the LHC one: • The process always starts, under vacuum control, with very short pulses of 20 µs every 20 ms • Power level is increased using short pulses up to full power passing slowly through all power levels to avoid “de-conditioning” • Same procedure repeated for initially short then longer and longer pulses up to the maximum length • The conditioning process will be considered finished when the vacuum level decreases below a predefined level (1 x 10-8 mbar for example), while ramping the maximum length pulse Eric Montesinos / CERN-BE-RF-SR

  24. Double walled tube rough estimate: 15’000 CHFCoupling box rough estimate: 25’000 CHF Eric Montesinos / CERN-BE-RF-SR

  25. SPL-CEA rough estimate:53’000 CHF Eric Montesinos / CERN-BE-RF-SR

  26. SPL-SPS rough estimate:27’000 CHF Eric Montesinos / CERN-BE-RF-SR

  27. SPL-LHC rough estimate:30’000 CHF Eric Montesinos / CERN-BE-RF-SR

  28. Mass production Eric Montesinos / CERN-BE-RF-SR

  29. New proposed schedule • Integrate advice and launch as soon as possible: • One pair of coaxial air cooled window • One pair of cylindrical air cooled window • Have 2 pairs ready for tests beginning 2011 • Decide which ones to construct in March 2011 (still three possible choices) • Construct remaining couplers in 2011 • Have 8 fully ready and conditioned couplers beginning 2012 Today: coupler review Confirm the Saclay test stand availability in 2011: February and end of year? Eric Montesinos / CERN-BE-RF-SR

  30. Conclusion: still a lot to do… • Eight couplers could be ready within two years: • Necessarily based on existing designs and very well known processes • Coaxial air cooled and cylindrical air cooled versions to be tried: • Potentially inexpensive for mass production • Interesting for large machines • Keep the coaxial water cooled option open: • Study the modification of the cooling from water to air • Redesign the waveguide transition for: • Less stress to the ceramic • Easier DC biasing Eric Montesinos / CERN-BE-RF-SR

  31. Many thanks for your patience Eric Montesinos / CERN-BE-RF-SR

More Related