RISP SSR1 Design - `Balloon’ TRIUMF/PAVAC

Specification Frequency325MHz Op. Temp.2K Q0Q0 5e9 E peak 35MV/m V acc 2.5MV QeQe 8e6 RF BW.40Hz df/dp<10Hz/mbar Tuning range±100kHz Pressure load2 (~300K)Bar 5 (~2K)Bar

Multipacting suppression

RF Design Cavity RF Parameters Frequency325MHz β0.3 L eff 277Mm G93Ω R/Q233Ω E peak /E acc 3.84 B peak /E acc 6.07mT/(MV/m) Operational Parameters E peak 35.0MV/m V acc 2.52MV E acc 9.11MV/m B peak 55.3mT U13.4J Multipacting Simulation E-Field M-Field

Mechanical Design ParametersBeam Tube C.CoefficientUnit Stress on Cavity (at 1bar) Fixed 18.5 Mpa Free 17.4 Stress on Jacket (at 1 bar) Fixed 32.2 Mpa Free 32.9 Pressure Sensitivity (df/dp) Fixed +7.7 Hz/mbar Free -2.0 Lorentz Force Detuning Fixed -1.4 Hz/(MV/m) 2 Free -8.7 Tuning Sensitivity N/A 467kHz/mm N/A 14.6kN/mm N/A 92MPa/mm Tuning Freq. Range±100kHz Stroke0.43mm Force6.3kN Cavity Stress39.5MPa Max. Allowable Stress Niobium 300K32*Mpa 2K171*Mpa SS 316L 300K115**Mpa 4K287***Mpa *Fermilab Technical Note TD Determined in accordance with ASME Section II - Part D - Appendix 1. **ASME Section II - Part D - Subpart 1. ***Suzuki K. (1988). Journal of Test and Evaluation 16, 190. Determined in accordance with ASME Section II - Part D - Appendix 1.

Fillet radius Cone ID Cone OD Jacket Pressure sensitivity – Optimize jacket geometry to minimize df/dp – Compensate frequency perturbations on E/M-field regions

Cavity Dimensions Cavity Diameter570mm Length (Iris)190mm Length (Ribs)376mm Length (Flange)390mm Width (Flange)718mm Thickness3mm Jacket Diameter590mm Length400mm Thickness3mm

Fabrication Sequence – Half cells Deep-drawing Machine beam tubes and flanges Braze beam tube and flange Weld beam tube to half cell Weld ring stiffeners Machine openings for spoke and RF tubes – Spoke Deep-drawing Weld 2 half pieces Machine drift tube Weld drift tube Machine stiffeners Weld stiffeners – Frequency control Stack half cells and spoke RF measurement Ground iris - frequency tuning RF measurement – RF ports Machine RF port tubes and flanges Braze RF port tube and flange – Cavity Weld 2 half cells Weld RF port tube to cavity Weld spoke Current SSR1 bare cavity model

Frequency Tuning 1 st step – Trim iris – Done after half cell welding and RF measurement accomplish – Compensate frequency errors from deep- drawing and machined parts and some welding shrinkage – Sensitivity ~850kHz/mm for both sides – ±2mm provides ±1.7MHz tuning range – Iris thickness is kept in range of 10mm to 14mm – 2% influence on E peak – Not affect cavity flange-to-flange length 2 nd step – Squeeze or stretch beam pipe flanges – Done after cavity fabrication accomplish – Compensate frequency errors from welding shrinkage and assembling of RF measurement – Sensitivity ~470kHz/mm – ±100s kHz tuning range

Post Processing HPR – Nozzles design At least 6 nozzles are required Nozzles distribute each 30 ˚, shown right 8 ˚ divergence angle of water jet – Coverage Visual check with SolidWorks model RF ports – cavity shell, spoke (transverse direction), RF tube Beam ports – beam tube, drift tube, spoke (longitudinal direction) Both ports – iris BCP – Main acid flow is from RF port to the other Cover most inner surface except beam tubes Flip cavity to get uniform etch amount – Additional path from beam pipe to the other Cover the beam tubes 8˚8˚ 30 ˚