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BNL 3 Cavity Design

BNL 3 Cavity Design. Ilan Ben-Zvi, Rama Calaga, Harald Hahn, Elliott C. Johnson, Jorg Kewisch, Wencan Xu (BNL and Stony Brook University, Long Island, New York). The BNL High-Current R&D ERL. Aimed at pushing the limits for beam current: 0.5 amperes and developing ERL technologies

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BNL 3 Cavity Design

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  1. BNL 3 Cavity Design Ilan Ben-Zvi, Rama Calaga, Harald Hahn, Elliott C. Johnson, Jorg Kewisch, Wencan Xu (BNL and Stony Brook University, Long Island, New York).

  2. The BNL High-Current R&D ERL • Aimed at pushing the limits for beam current: 0.5 amperes and developing ERL technologies • Testing of novel components and techniques: • Superconducting electron gun • Diamond amplified photocathode • Z-bend ERL beam merging • High-current SRF cavity at 703.75 MHz • Diagnostics and more. • Collaboration with AES

  3. SRF Gun

  4. Load-lock 3rd Gen Deposition System • Multi-alkaline capability • Base pressure 1x10-10 Torr • System designed to eliminate cross contamination of sources • Provides for quicker source exchange • 2 UHV transport systems with LN2 cooling capability

  5. ERL layout. Straight section is 7m long

  6. Dmitry Kayran

  7. ERL Beam Design Parameters

  8. R&D ERL in mode aiming to cause BBU Dmitry Kayran, Harald Hahn, Lee Hammons, Jorg Kewisch.

  9. Maximum stable Q in 4 GeV 3-pass ERL, at 0.3 A and a single dipole HOM with R/Q=100 Ω. These numbers are arbitrarily selected to demonstrate the application of the BBU code. Jorg Kewisch.

  10. Design of new ERL cavityWencan Xu Hallmarks: Improved SRF properties and HOM damping. Use pick-up probes rather than ferrites or waveguides. HOM power conducted through coax lines to room temperature loads.

  11. Wencan Xu

  12. Comparison: New and original

  13. Comparison to other cavities

  14. HOM trapping

  15. Performance in terms of BBU

  16. Band-stop filter designWencan Xu A band-stop filter is simpler and safer than a notch filter.

  17. Single cell with band pass filter

  18. Scaling of Field for the following

  19. Electric Field MV/m 3.49e-5 4.79 9.59 14.38 19.17 23.97 28.76 33.55 38.34 43.15 Electric field

  20. Magnetic Field A/m 0.0 7180 14359 21503 28682 35862 43041 50185 57365 64544 Magnetic field

  21. Structural Model Axisymmetric Model 1.06 meters 3 mm thick 1.98 mm thick 3 mm thick

  22. Lorentz Pressure psi -.553 -.474 -.396 -.318 -.240 -.162 -.083 -.005 .073 .151 Lorentz Pressure When KL is positive the frequency shift is negative Positive pressure is into the surface

  23. Axial displacements inches -.291e-3 -.225e-3 -.159e-3 -.925e-4 -.263e-4 -.399e-4 .106e-3 .172e-3 .239e-3 .305e-3 Model Deflection Free – Free Boundaries Axisymmetric Model Model held at center axially Deformed geometry Original geometry Lorentz Detuning Coefficient 4.01 Hz/(MV/m)^2

  24. Axial displacements inches -.146e-4 -.110e-4 -.737e-5 -.378e-5 -.190e-6 .340e-5 .699e-5 .106e-4 .142e-4 .178e-4 Model Deflection Fixed – Fixed Boundaries Axisymmetric Model Model held at ends axially Original geometry Deformed geometry Lorentz Detuning Coefficient .579 Hz/(MV/m)^2

  25. Location of Stiffeners 10.45 cm 10.45 cm Center stiffeners at radius of 12.78 cm 10.45 cm 10.45 cm Center stiffeners at radius of 11.61 cm Stiffeners centered at radius of 10.45 cm

  26. Lorentz Coefficient for Different Stiffener Locations

  27. Design of a copper prototype (AES) 6x Claw clamps 6x Threaded Rods FPC End Group CRES Flange Pickup Probe End Group

  28. Beam Pipe joints CRES Flange brazed to Cu Transition pipe Cu- welded- to - Cu joints Conflat Flange Cu Beam Pipe pilots and clamps into CRES Flange CRES Flange brazed to Cu Beam Pipe Low Power Cu SPL

  29. SUMMARY • A new R&D ERL is in advanced construction • ERL is a test-bed for high current technologies • Development of new cavity • New features: • Better SRF performance • Probe with coax line and band-stop filter • The result - a universal 704 MHz cavity.

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