1 / 23

Superconducting Cavities at 200 MHz Fabrication and Performance

Superconducting Cavities at 200 MHz Fabrication and Performance. H. Padamsee. Rongli Geng, Enrico Chiaveri and Roberto Losito. Goals. Extend SRF to 200 MHz ->large scale SC cavities Aim for Nb-Cu to cut Nb material cost Aim for.. Epk (at surface) = 25 - 30 MV/m

gitel
Download Presentation

Superconducting Cavities at 200 MHz Fabrication and Performance

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. Superconducting Cavities at 200 MHz Fabrication and Performance H. Padamsee Rongli Geng, Enrico Chiaveri and Roberto Losito

  2. Goals • Extend SRF to 200 MHz ->large scale SC cavities • Aim for Nb-Cu to cut Nb material cost • Aim for.. Epk (at surface) = 25 - 30 MV/m • Develop large scale cavity fabrication methods • Need ≈ 600 cells

  3. 200 MHz Cavity - Ready for Test 400 mm diameter beam pipe-> 300

  4. First Test Results (Summer 02) Need to • Reduce field emission • Improve processing

  5. Multipacting Simulations SEC=3.0 SEC =2.5

  6. Re-Rinse at CERN, HPR, Fixed Probe Epk=17 MV/m

  7. X-Radiation Levels

  8. 3rd Test Jan 03, long time He processing Radiation level Still 30 R

  9. Q-Slope = Material Property of FilmsDepends on Film Quality and Cu Substrate Also Nb-Cu 1500 MHz Bulk Nb

  10. CERN 350 MHz LEP Cavities

  11. Q-Slope Decreases with Temperature 400 MHz LHC Measured

  12. Q-Slope Decreases With Frequency MeasuredDependence of Q-Slope

  13. 200 MHz, Expected From Temp and Frequency Dependence

  14. What Next? CERN has already built a second Nb-Cu cavity by the same method. This will test variability in film properties. Could re-coat with Krypton

  15. What Next? Niobium sputtering • Sputtering parameters • Discharge current stabilized at 3 A. • Sputter gas pressure of 1.5x10-3 mbar, corresponding to ~ 360 V. • Coating temperature is 150 °C. • Thickness: 1.5 µm • Film characteristics (same as for LEP): • RRR: 11.5 ± 0.1 • Argon content: 435 ± 70 ppm • Grain size: 110 ± 20 nm • Tc: 9.51 ± 0.01 K

  16. AFM Results on Surface Structure of Nb/Cu

  17. Compare Large and Small Grains Standard films Oxide-free films

  18. Better Films with Krypton

  19. Large Scale FabricationINFN Spinning 500 MHz Cavity from Tube

  20. Dimension Check Several Cavities Received

  21. Explore Bias Sputtering Using 500 MHz Cavities Argon Ion bombardment of Nb film should increase film smoothness

  22. Conclusions • First ever 200 MHz Nb-Cu Cavity completed successfully • Test facilities ready at Cornell • First results very encouraging (Eacc = 11 M/m CW), surface E field = 19 MV/m..Goal 25-30 MV/m • Further work needed to reduce Nb-Cu Q-slope.. • Re-sputter with krypton gas • Explore Bias magnetron sputtering • Continue efforts to process to reduce field emission • Spinning of 500 MHz copper cavities from tube successful

More Related